Reprinted from "ENGINEERING," February 28, 1890. THE FORTH BRIDGE.
Reprinted from "ENGINEERING," February 28, 1890.
THIBD EDITION, BEVISED, WITH APPENDIX.
LONDON :
OFFICES OF "ENGINEERING," 35 & 36, BEDFORD STREET, STRAND, W.C. CONTENTS.
PAGE HISTORICAL 1 RAISING OP THE APPROACH VIADUCT GIRDERS, AND UNDERBUILDING ON CANTILEVER BRIDGES GENERALLY OF THE PIERS 5 .. 32 THE STEEL SITE OF BRIDGE AND PROFILE ON CENTRE LINE. SURROUNDING 35 COUNTRY 7 DRAWINGS 37 TIDES, WIND, WIND PRESSURES, AND GAUGES. CLIMATE GENERALLY 7 WORKSHOPS 37 WIND PRESSURE AND WIND GAUGES 9 BEDPLATES 39 EXPERIMENTS ON WIND STRESSES ...... 10 THE MEMBERS FORMING THE CANTILEVERS 47 GENERAL DESCRIPTION OF THE STRUCTURE 10 BUILDING OUT OF THE CANTILEVERS 50 COMMENCEMENT OF WORK 12 RIVETTING 59 TRANSPORT AND DISTRIBUTION OF MATERIAL ...... 14 TEMPORARY WORK IN CONNECTION WITH THE ERECTION 59 LIGHTING 14 THE USE OF WIRE ROPE 60 MATERIALS OF CONSTRUCTION FOR THE MASONRY PIERS 15 THE PERMANENT WAY 61 WATER 16 EXPANSION JOINTS IN RAILS 61 CEMENT ... 17 PAINTING 61 COMMENCEMENT OF THE PERMANENT WORK 17 ASPHALTING 61 GENERALLY ABOUT COFFERDAMS 17 THE WORKMEN 61 INCHGARVIE NORTH CIRCULAR PIERS 18 THE RAILWAY CONNECTIONS 62 FIFE SOUTH CIRCULAR PIERS 18 THE SOUTH APPROACH RAILWAY 63 SOUTH APPROACH VIADUCT PIERS 19 THE NORTH APPROACH RAILWAY 63 PRELIMINARY WORK IN CONNECTION WITH THE INCHGARVIE SOUTH WEIGHT OF THE SUPERSTRUCTURE 63 PIERS 19 THE FORTH BRIDGE RAILWAY COMPANY 63 PRELIMINARY WORK IN CONNECTION WITH THE FOUR QUEENSFERRY THE VISITORS ... CAISSONS 21 64 THE PRELIMINARY TESTS BUILDING OF THE CAISSONS 23 64 ENGINEERS THE AND CONTRACTORS OF THE FORTH BRIDGE : AIR COMPRESSORS 23 SIR JOHN FOWLER, K.C.M.G 64 ACCIDENT TO No. 4, OR QUEENSFERRY SOUTH-WEST CAISSON ... 26 MR. BENJAMIN BAKER 69 SINKING OF THE CAISSONS 27 SIR THOMAS TANCRED 69 QUEENSFERRY CAISSONS 29 MR. WILLIAM ARROL 69 INCHGARVIE CAISSONS 30 MR. T. H. FALKINER 70 THE CIRCULAR GRANITE PIERS 31 MR. JOSEPH PHILLIPS 70 MONS. L. COISEAU 71 APPENDIX.
INSPECTION AND TESTING OF THE FORTH BRIDGE BY THE BOARD OF TRADE. 71
LIST OF PLATES.
PLATE TO FULL HEIGHT. FIFE PIEU, FROM THE NORTH-WEST. I. PORTRAIT OF SIR JOHN FOWLER, K.C.M.G. PLATFORMS RAISED TO FULL HEIGHT. II. PORTRAIT OF MR. BENJAMIN BAKER. XII. FIFE CANTILEVER. SIDE ELEVATION LOOKING EAST. III. THE FORTH BRIDGE. XIII. EFFECT OF SEA FOG. CENTRAL TOWERS AND SOUTH APPROACH IV. GENERAL VIEW OF BRIDGE SOUTH CENTRAL GIRDER CONNECTED ; ; VIADUCT. H.M.S. "DEVASTATION" PASSING FIFE PIER. NORTH CENTRAL GIRDER NOT COMPLETED. GENERAL VIEW OF CENTRAL TOWERS AND APPROACH VIADUCTS, V. GENERAL VIEW OF SITE LOOKING NORTH-EAST. CAISSON BUILDING LOOKING NORTH. QUEENSFERRY NORTH-EAST PIER. PUTTING ON LAUNCHING WAYS. TOGETHER UPPER BEDPLATE. VI. VIEW FROM INCHGARVIE CASTLE. THE SOUTH CAISSON IN POSITION. XIV. INCHGARVIE PIER. RIVETTING IN TOP MEMBERS BETWEEN VERTICAL COLUMNS. PIER. INTERSECTION OF DIAGONAL VII. LAUNCHING OF CAISSON FOR SOUTH-WEST PIER, INCHGARVIE. QUEENSFERRY WITH AND DIAGONAL BRACING GIRDERS. GENERAL VIEW OF SITE, WITH PIERS OF SOUTH APPROACH STRUTS HORIZONTAL VIADUCT, LOOKING NORTH. BUILDING OF NORTH-EAST CIRCULAR XV. FIFE PIER. FIRST HALF-BAY IN FIXED CANTILEVER, SHOWING GRANITE PIER, INCHGARVIE. CAISSON FOR QUEENSFERRY LIFTING PLATFORM FOR BUILDING THE LOWER PORTION OF NORTH-WEST PIER. CONSTRUCTING TIMBER CASING ROUND BAY, AND TOP MEMBER CRANE WITH PLATFORM SUSPENDED THE TILTED CAISSON. FROM rr. MAKING GOOD A CROSSING BETWEEN STRUTS AND VIII. FRONT VIEW OF NORTH CANTILEVER END PIER, AND VIEW OF TIES IN FIRST BAY OF CANTILEVER. VIADUCT AND ARCHES. NORTH APPROACH RAISING PIER HORIZONTAL AND DIAGONAL VIADUCT ; XVI. CENTRAL TOWER, QUEENSFERRY ; VIADUCT GIRDERS. NORTH APPROACH PART OF INTERNAL VIADUCT AND TEM- VIADUCT ; GIRDERS BRACING GIRDERS ; RAISED TO FULL HEIGHT. PORARY STAGING. QUEENSFERRY PIER. INTERNAL VIADUCT FROM CENTRE OF BAY TO WITHIN CENTRAL TOWERS. IX. FIFE PIER. ERECTION OF SUPERSTRUCTURE ; CONSTRUCTION OF LIFTING PLATFORMS. INCHGARVIE PIER. ERECTION OF SUPER- XVII. FIFE PIER. LOWER HALF OF FIRST BAY IN FIXED CANTILEVER. LOWER HALF OF FIRST STRUCTURE ; RIVETTINO CAGES AND HYDRAULIC RIVETTING FIFE PIER. CENTRAL TOWER AND MACHINES ON VERTICAL COLUMN AND DIAGONAL STRUT. BAY IN FREE CANTILEVER. FIFE PIER. ERECTION OF SUPERSTRUCTURE LIFTING PLAT- ; XVIII. FIFE PIER. FREE CANTILEVER COMPLETED AND CENTRAL GIRDER FORMS ABOUT 100 FT. ABOVE HlGH WATER. CAGE FOK COMPLETED. COMMENCED ; FIXED CANTILEVER NOT QUITE RlVETTINU AND BUILDING BOTTOM MEMBERS. XIX. QUEENSFERRY PIER AND INCHGARVIE SOUTH CANTILEVER, WITH X. QUEENSFERRY PIER, LOOKING NORTH. LIFTING PLATFORMS ABOUT PARTS OF CENTRAL GIRDER BUILT OUT. INCHGARVIB SOUTH 190 FT. ABOVE HIGH-WATER LEVEL. CANTILEVER, WITH FIRST BAY OF CENTRAL GIRDER BUILT LOOKING INTERNAL VIADUCT XI. QUEENSFERRY PIER, NORTH. PLATFORMS RAISED TO FULL OUT. CENTRAL TOWER ON INCHGARVIE ; HEIGHT. FIFE PIER, LOOKING SOUTH. PLATFORMS RAISED GIRDERS AND WIND FENCE.
403025 LIST OF ILLUSTRATIONS.
PAGE MAP SHOWING THE FORTH BRIDGE AND RAILWAY CONNECTIONS ... 2 FIG. 1. ANDERSON'S DESIGN FOR BRIDGE OVER THE FORTH, 1818 FIGS. 2 AND 3. ALTERNATIVE PRELIMINARY DESIGNS FOR THE FORTH BRIDGE FIGS. 4 AND 5. THE FORTH BRIDGE, CANTILEVER TYPE ; ORIGINAL AND FINAL DESIGNS FIGS. 6 TO 15. TYPES OF CANTILEVER BRIDGES FIG. 15A. LIVING MODEL, ILLUSTRATING PRINCIPLE OF THE FORTH BRIDGE FIG. 16. MAP OF THE FIRTH OF FORTH FIGS. 17 AND 18. WIND GAUGES ON INCHGARVIE FIG. 19. EXPANSION DIAGRAM OF FORTH BRIDGE FIG. 20. TEMPORARY STAGING ON INCHGARVIE FIGS. 21 AND 22. BEARING OF CAISSONS ON ROCK FOUNDATION... FIGS. 23 TO 28. DETAILS OF SOUTH APPROACH PIERS FIGS. 29 AND 30. INCHGARVIE SOUTH-WEST CAISSON FIG. 31. RAFT USED FOR SURVEY OF FOUNDATION FIG. 32. CUTTING EDGE OF CAISSON
FIGS. 33 TO 35. PNEUMATIC CAISSONS, QUEENSFERRY ... 20 FIG. 36. SECTION OF CAISSONS AT INCHGARVIE FIG. 37. CAISSON AND CRADLE IN LAUNCHING WAY FIGS. 38 AND 39. AIR LOCKS FIG. 40. Am LOCKS ON CAISSONS FOR ADMITTING AND REMOVING MATERIALS ......
FIGS. 41 TO 45.. AIR LOCK AND HOISTING GEAR ON CAISSONS ... FIG. 46. TILTED CAISSON AT SOUTH QUEENSFERRY FIG. 47. SECTION OF TILTED CAISSON AFTER COMPLETION FIG. 48. SINKING THE QUEENSFERRY CAISSONS FIGS. 49 AND 50. HYDRAULIC SPADE FIG. 51. SECTION OF CAISSONS WITH AIR LOCKS AND WORKING CHAMBERS
FLOATING OUT CAISSON FOR QUEENSFERRY PIER, MARCH 26, 1884 FIG. 52. STRUTS AND WEDGES IN AIR CHAMBER FIG. 53. PIER WITH PERMANENT CAISSON FIGS. 54 TO 59. MODE OF FIXING UNDER BEDPLATES ON PIERS FIGS. 60 AND 61. HEATING FURNACE FOR PLATES FIGS. 62 AND 63. HYDRAULIC BENDING PRESS FOR PLATES FIGS. 64 AND 65. MACHINE FOR PLANING ENDS OF CURVED PLATES FIG. 66. MACHINE FOR PLANING EDGES OF CURVED PLATES FIG. 67. PLAN OF DRILL ROADS FIGS. 68 TO 71. BOTTOM MEMBER ON DRILL ROAD FIGS. 72 AND 73. TUBE DRILLING MACHINE ON DRILL ROAD THE FORTH BRIDGE.
BY W. WESTHOFEN.
HISTORICAL. explanation of the many struggles and attempts beaten down the Firth, and had finally to land on IT has at all times been a subject for contro- made by the East Coast lines to obtain a separate the island of Inchcolm, five miles away. He founded versy and a matter of difficulty to fix the precise access to the counties north of the Forth. How a priory on that island as a thanksoffering to boundary line between the river and the sea, that great the necessity was of having means of com- Providence for a very narrow escape and in view is to say exactly where the sea ends and the munication between the two shores, and how largely of a warmer reception and more substantial enter- river commences. With regard to the Forth and even the inadequate provisions made hitherto were tainment should a similar misfortune again befall its estuary, the same discussion has been carried taken advantage of, is proved by the fact that in him. So must also many of the poor wayfarers who on in Parliament and elsewhere with considerable 1805 before a steamboat existed or a railroad was got drenched to the skin and suffered the horrors warmth, but does not appear at the present moment thought of the right of running ferryboats between of sea-sickness during the crossing, and so must to have got any nearer to settlement than in 1882. South and North Queensferry was let at a yearly finally if there was time for them to do so the a in Fife- rental of 2000?. and it is stated in the unfortunate of who were driven down Taking, however, point, say Anstruther, , Parliamentary party people shire, and another, say Dunbar, in Haddington- evidence then taken that the revenue derived by the Hawes Brae at so rapid a pace that horses, shire, and drawing a line across which, roughly outsiders who run goods and passengers across in carriage, and passengers went right off the pier speaking, passes near the May Island and the Bass yawls and small boats amounted to fully 5000Z. per into the water and none of them came out alive. Rock, we may call it the Forth within and the sea annum in addition. The idea thus floated through many minds until without this imaginary boundary line. Starting It must be admitted that the Forth Bridge crosses about 150 years ago, when a bridge was first spoken westward from it we have 32 miles to Queensferry the river at a point which leaves the eastern counties of, but particulars as to design, site, or probable and 30 miles further to Stirling. On both sides of still somewhat in the same difficulty, but it reduces cost do not seem obtainable. this great watershed are situated hundreds of square many of the local distances to be traversed In November, 1805, a proposal was made to con- miles of some of the most fertile and best cultivated by more than one-half, and the gain in time is con- struct a double tunnel 15 ft. wide and about the land in the three kingdoms. There are great coal- siderable. Going by the Forth Bridge and its same in height quaintly described as one for fields, there is mineral wealth and, besides, an im- connecting lines the traveller will now be carried comers and one for goers under the bed of the mense supply of food and other commodities which to and safely landed at Perth, Dundee, or Aberdeen, Forth, at some point to the west of Queensferry. the inhabitants of these districts would wish to ex- as the case may be, in a comparatively short time The project, was evidently seriously entertained, for change or barter. But a serious barrier stood in after leaving Edinburgh in one and a quarter in July, 1806, a prospectus was issued by "a number the way, and stands even to this day, for the only hours, one and three-quarter hours, and four hours of noblemen and gentlemen of the first respecta- means of intercommunication and of transport be- respectively independent of wind or tide and bility and scientific character," inviting the publ'c at lOOi. each. tween the two shores is afforded by steam ferries or without difficulty and discomfort. In speaking of to subscribe the shares being fixed craft. Of the former there are three the new lines in connection with the this in a of about 120 by sailing bridge Further, 1807, pamphlet " pages the most seaward is that from Granton to Burnt- matter will be further referred to. was published in Edinburgh, entitled Observatior s five miles and 24 miles the Forth The for the construction of so on the and of island, long, up ; justification great Advantages Practicability making the next is that between South and North Queens- a work must, however, be sought in the desire to Tunnels under Navigable Rivers applicable to the 32 miles from the line the serve interests than those of local traffic Tunnel under the Forth. Illustrated with ferry, boundary ; and larger proposed third at Kincardine, about 15 miles west of Queens- merely. In these days of high pressure, of living a section and map." Nothing, however, seems to ferry. The first bridge for railway traffic is at Alloa, and working and eating and drinking at top speed, have come of the project, whether owing to diffi- is not 20 miles from Queensferry, and the next at Stirling. the saving of an hour or two for thousands of culties of construction or of financing known The Granton-Burntisland passage (see map on the struggling men every day is a point of the greatest most probably both. next page) is seriously affected by the weather in the importance, and every delay, however excusable Within eleven years another effort was made, and winter months, is often impassable during strong and unavoidable, is fatal to enterprise. Nor must we come upon a pamphlet entitled "Report relative gales, andatthebestof timesthe disembarkation from the bridge be looked upon as a thing standing by to a Design for a Chain Bridge thrown over the James train to boat and from boat to train is a source of con- itself, but rather as a portion certainly a some- Firth of Forth at Queensferry By siderable discomfort to passengers, and what is worse what expensive portion of a gigantic system of Anderson, civil engineer and surveyor, Edinburgh, a great waste of time. The same holds good, though railway lines converging from all directions upon 1818." There were three elevations, differing as to in a minor degree, at Queensferry and at Kincardine, the capital of Scotland, affording means not only of height and length of clear span, but all equally bold and the traveller who to comfortable butalso and we on the next but requires go from Dunbar more speedy and more travelling, equally primitive ; give page to Anstruther, to put an extreme case, and who giving facilities for the provision of a larger number one a reproduction on a smaller scale of the diagrams objects to either of the sea passages, has no choice of those through trains which are constantly be- accompanying this report. The site was to have left him but to go round by Alloa or Stirling, and coming more necessary by the yearly addition of been nearly the same as that of the present bridge, to pass over about 150 miles of railroad, when the many miles of both main lines and branch lines. starting from the same point at North Queensferry, of distance between the two towns mentioned is, as Altogether those concerned in this great undertak- passingverynearlyover the centre Inchgarvie, and of a the crow flies, less than 18 miles. That under such ing are sanguine that within a very few months the terminating on the south shore about one-third conditions the commercial and agricultural inter- courage, the foresight, and the wisdom of the mile east of the Hawes Pier, joining the Edinburgh course and traffic between the eastern counties of directors of the Forth Bridge Railway Company, Road just under Mons Hill. The clear height above r Scotland suffered a serious check, and became and of the other interested railway systems, will be high w ater was to have been either 90 ft. or 110 ft., for reduced to a minimum, was but to be expected. fully proved by results which it is impossible to the main spans 1500 or 2000 ft., the width The same disadvantages existed in the case of estimate even approximately just now. carriage road and footpath 33 ft., and the cost all those travellers, bent on business or on pleasure, When and with whom the idea of bridging the 175,000/. or 205,000;. The time required for com- from north to south or vice versa, who desired to Forth first originated is now a matter of pure con- pletion was stated to be four years. A revenue of pass through Edinburgh on their way, and who had jecture. The Roman leader bent on exploration 10 per cent, on the capital expended was considered either to cross by one of the ferries or make the and conquest, probably conjured up in his mind's a very moderate estimate, which proves that the art is of long detour by Stirling, being in either case eye the faint outlines of a bridge as he trudged the of writing a highly coloured prospectus oldel compelled to submit to a loss of valuable time. weary miles along the south shore and found neither date than most people would have thought. To Finally, the principal railway companies whose boats to carry him across nor ford to traverse so judge by the estimate the designer can hardly have systems are situated in the eastern and midland must often have the sainted Margaret, the wife of intended to put more than from 2000 to 2500 tons counties of England and the south of Scotland, Malcolm Caen-Mohr, on her frequent pious pilgri- of iron into the bridge, and this quantity distributed could get no access to the northern parts of mages between Edinburgh, Linlithgow, and Dun- over the length would have given the structure a Scotland except by passing over the lines of a fermline about the time of the Norman Conquest, very light and slender appearance, so light indeed company whose interests were hostile and in and so probably her son Alexander the First of that on a dull day it would hardly have been visible, opposition to their own. This brought about a Scotland, who in attempting to cross from South to and after a heavy gale probably no longer to be seeu most intolerable state of things, and is an easy North Queensferry was overtaken by a gale and on a clear day either. This scheme also and for to a channel clear, the side. The at and on Fife were , proved abortive, forty dredgers keep although ferry piers Queensferry steamer draws little more than ft. of water. in years more the travelling public put up with what they 4J very nearly the same position as those of the British These conditions are a source of discomfort to could get, but at last in I860 the North much present bridge, and there were two approach Railway fixed upon a site about six miles to the the passengers by this route for the light draught viaducts to reach the high ground upon either side. west of South Queensferry as suitable for the con- steamer can hardly hold its own against a gale of The bridge was to have been constructed entirely struction of a railway bridge. The bridge was to wind broadside on, and many people become sea- of steel. have consisted of a number of largo spans of 500 ft. sick during a passage lasting at the worst of times Offices and workshops which are now standing in shorter minutes. were built at and eweh in the tentrte, Jvith approaches spans barely twenty Queensferry, extensive brick- * at either end.; tSl4 xact centre line was to have In 1873 the Forth Bridge Company was formed works near Inverkeithing laid out and started. A Castle on the for the of out the Sir brick one of , a Blackness which were to form the been t from point hei)r purpose carrying design by pier eight, 'fwJuih dicre'tb Charleston on the north shore, and i Thomas Bouch of a suspension bridge with two base of the great Inchgarvie tower was built at 'line* -ftdnu ^near on the of 1600 ft. each. The was the extreme north-west after a foundation connecting Linlithgow, j large spans capital corner,
PLAN showing tha FORTH BRIDGE, RAILWAY CONNECTIONS.
Edinburgh and Glasgow line on the one side, and raised by the four principal railway companies' stone had been laid with great ceremony. But the from Charleston to Dunfermline on the other side, interested in the East Coast traffic namely, the collapse of the ill-fated Tay Bridge in December, would no doubt have established a very good through Great Northern, the North-Eastern, the Midland, 1879, stopped the further progress of the work, line to the north. Borings were taken and other and the North-British, and the companies came to and the investigations into the causes of that investigations made. A design had been drawn out an understanding among themselves that they disaster, and the disclosures made, shook the by Sir Thomas (then Mr.) Bouch, and Parliamentary would between them send so much traffic across public confidence in Sir Thomas Bouch's design, powers for the construction of the bridge were i the bridge as would suffice to pay a dividend of and rendered a thorough reconsideration of the obtained by an Act in 1865. The river here is about 6 per cent, per annum on the contract sum. The whole subject necessary. As a first result of this, j Z\ miles wide, and the greatest depth of water about 1 Act authorising the construction of the bridge was the suspension bridge was abandoned, and the four 60 ft. but the bottom is loose and uncertain, and in the same year, 1873, and a contract signed railway companies above named instructed their j passed it was decided to build up and sink an experimental , withMessrs. W.Arrol and Co., of Glasgow. Anillus- consulting engineers Messrs. Barlow, Harrison, pier before proceeding further. But troubles inter- tration showing elevation and plan of Sir Thomas and Fowler to meet and consider the feasibility vened, and during the re-arrangement of the North Bouch's design is shown in Fig. 2. The central of building a bridge for railway purposes across the British Railway Company in 1866-1867, the project 1 towers from which the main chains are suspended Forth, and assuming the feasibility to be proved, was abandoned through various causes. For it were were to have been 550 ft. above high water, while to decide what description of bridge it. would be substituted improvements in the Queensferry the rail level would be at such height as to leave a most desirable to adopt. It was fairly, well known 1 passage by the construction of the railway slips at clear head-room of 150 ft. above high water between how many types of bridge there were to select North and Port It was at first the The central tower on was over from for such a site these were Mr. Bouch's Queensferry Edgar. piers. Inchgarvie ; (1) : intended to have at each 500 ft. the foundations ! which of sus- swinging landing-stages long, brought upon original design (Fig. 2) ; (2) three forms end, and with the tide the trains the rock down to a of over 110 ft. with and braced rising falling by , sloping depth pension bridges stiffening guides means of these to be run on and off the 1 lines of rails chains and a ferry below high water. There were two (Fig. 3) ; (3) cantilever bridge (Fig. 4). steamers. The latter portion of the scheme was not carried at a distance of 100 ft. from each other, The inquiry was most comprehensive. It embraced carried out to the insufficient line a of not as set however, owing depth I each being supported on pair strong only bridges forth, but also tunnels, and of water and tho near the lattice and these were stiffened both of these for different sites. gradual silting up piers, , girders, laterally which necessitates the assistance of from side to With to it was considered that periodical ; by single diagonal bracings reaching regard tunnels, the of water in the two main channels to construct a with great depth expedient bridge shorter spans finally adopted, and Messrs Fowler and Baker were above 200 ft. and the both than those which are indicated the natural ! high ground upon by con- appointed engineers to carry it into execution would necessitate and of the shores, very steep gradients figuration ground. In July, 1882, an Act of Parliament was obtained the tunnel miles 1 he for a continuous long approaches making many original design girder bridge authorising the construction of the bridge and sane- of the of the nature | on the cantilever and long, irrespective uncertainty (see Fig. 4) central girder tioning the new financial arrangement by which the
LONGITUDINAL. SECTION. Abutment Hcrthera Abutment Southern
Perspective- View ground Plan of Abutment TRANSVERSE SECTION. SideElevabonafaPier rniwersc Elevation ofa Pier of Internal part of Abutment Side llwat>on of M Abutment.
Ground Ran LONGITUDINAL SECTION Northern Abutment
Fio. 1. ANDERSON'S DESIGN FOR BRIDGE OVER THE FORTH, 1818. of the ground through which the tunnel would have principle which had been submitted by Messrs. capital of the Forth Bridge Company was guaranteed to be cut. Fowler and Baker was in some particulars modified with interest at 4 per cent, per annum, each of the All things considered, the most suitable site for to suit the conflicting views of the other consulting four contracting railway companies undertaking to was held to be that at and was then submitted to the directors find its share of the and its a bridge Queensferry ; and, engineers, capital expenditure pay owing to the great depth of water and the nature in May, 1881. After consultation with the officers share of the interest. It is also agreed that the North of the bottom of the estuiry, it was not considered of the Board of Trade, this design (see Fig. 5) was British Railway Company will maintain the per- o C, Q p > "3 -S
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There are thus two Registry, as determined by the experience ga ned in spectively. complete piers, as represented in the outline draw- the use of many thousands of tons of steel plates, . . i i 1 l __1 . f 1-1 -i i In 1871 Mr. Fowler and Mr. Baker made designs ing above their heads. The central girder is repre- bars, and angles for shipbuilding purposes. and estimates for a bridge across the Severn, com- sented by a stick suspended or slung from the two 4. That the maximum economy be attained consistent with the prising two girder spans of 800 ft. each, and in inner hands of the men, while the anchorage pro- fulfilment of the preceding con 1873 Mr. Baker, at the request of the Corporation vided by the counterpoise in the cantilever end ditions. We think it will be apparent to moit of Middlesbrough, designed the superstructure for piers is represented here by a pile of bricks at each engineers and bridge builders that the original sus- a proposed ferry bridge across the Tees, which end. When a load is put on the central girder by pension-bridge design complied with none of these and the whilst the included a 650 ft. span on the same system a person sitting on it, the men's arms conditions, girder design complies withal), Of the (ENGINEERING, vol. xvi., page 60). anchorage ropes come into tension, and the men's present design it may be truly said that all have been In 1876 nine competitive designs were submitted bodies from the shoulders downwards and the anticipations most brilliantly realised, for the New York and Island sticks come into The chairs are and its merits can now, in the of ex proposed Long compression. light practical ; and of actual Bridge, comprising one span of 734 ft. and one of representative of the circular granite piers. Imagine perience, facts, be mure easily pointed 618 ft., and of these three designs, two were on the aforesaid system (Figs. 13 and 14). The first was that of the Delaware Bridge Company, and the second of Colonel Flad, the very able engineer who, under Captain Eads, carried out the great St. Louis steel arch bridge. In the same year was built the first, and, so far as we know, the only railway bridge of the type under discussion (Fig. 15.) This is a bridge of 148 ft. span across the Warthe, near Posen. It might appear strange at first that the application to railway purposes of so well-known a system should have been deferred until 1876, but the explanation is that there are thousands of bridges in existence on the continuous girder, or in other words cantilever and central girder principle, but engineers as a rule have elected not to sever th bridge at the point of contrary flexure, or to make the girders of varying depth. A glance at the annexed illustrations and descrip tion will satisfy our readers that there is nothing. novel or untried in the principle of the structure designed for the Forth crossing. The reasons dictat ing the design in the case of the Forth Bridge an those which probably influenced the Red Indians ii making the structure illustrated by Fig. 8 econom; of material and facility of erection. It must b conceded, however, that except as regards prin ciple the design is essentially novel, but th novelties are dictated by the unexampled size of the structure, and are due simply to th< perfect adaptation of the principle of the com tinuous girder and the general laws regarding th( strength of materials to the special conditions of the case. Thus it will be observed that th structure is a continuous girder of varying depth on plan as well as elevation, the central girder portion being of the ordinary width required for a double line of rails, and the cantilevers spreading out to an extreme width of 120 ft. at the piers. By thi means the stresses on the horizontal bracing from wind pressure are much reduced, and lightness and compactness areattained. To further the same ends the whole of the vertical members are made of two struts inclined towards each other from base to summit and braced together. To reduce the extreme height of the structure, and bring the centre of gravity as low down as possible, the bottom members of the continuous girder are curved, springing from solid masonry piers at a height of 18 ft. only above high water, whereas in the design for the suspension bridge the main chains, carrying of course all the weight, were supported at a height of 550 ft. above the same point ! The main compression members are steel tubes ranging up to 12 ft. in dia- meter, the tubular form being adopted for two reasons, firstly, because experiments have shown that inch for inch the tubular form is stronger than FIG. 9. any other, and, secondly, because the amount of TYPES Or CANTILEVER BRIDGES'. stiffening and secondary bracing is thereby reduced to the lowest percentage. It might be thought that ;he chairs one-third of a mile apart and the men's out. In the first instance the distribution of weight columns 350 ft. in length were an untried novelty, leads as high as the cross of St. Paul's, their arms not only offers the advantage of having the greatest but this is not as have so, we the precedent of the represented by huge lattice steel girders and the proportion, nearly one-fourth of it, immediately Saltash Bridge oval tubes 16 ft. 9 in. by 12 ft. 3 in. sticks by tubes 12 ft. in diameter at the base, and over the main supports, where it is most easily in diameter and 460 ft. in length, the strain upon i very good notion of the structure is obtained. erected, but it offers in those places where the wind which the under test load was higher per square inch The chief desiderata in the Forth Bridge, which pressure would act with the greatest amount of than will be that on the steel columns of the Forth s the largest railway bridge ever yet built, were leverage, the least amount of surface to act upon. Bridge. The central girder portion is simply an ;learly as follow: Thus, while in the central tower of the Inchgarvie double-line ordinary railway bridge of 350 ft. span 1. The maximum attainable amount of rigidity, pier, the most exposed to storms, the weight per with girders of a type intermediate between the >oth vertically under the rolling load and laterally foot run is 23 tons, and in the first bay of canti- of girder parallel depth and the bowstring. This is under wind pressure, so that the work when completed levers 21 tons, in the central girders of 350 ft. an economical type, and many Continental bridges Tiay by its freedom from vibration gain the confi- length it is only a little over 2 tons per foot. In a have been so constructed. lence of the and the of similar manner the structure decreases in When public, enjoy reputation rapidly lecturing some years ago, Mr. Baker, with ieing not only the biggest and strongest, but also height and breadth of girders, as it extends from a view of presenting in a form easily understood he stiffest bridge in the world. the massive central towers towards the extremities of and popularly remembered, a simple diagram of the 2. Facility and security of erection, so that at any the cantilevers. Again, for purposes of erection every manner in which the principal stresses of a canti- tage of erection the incomplete structure may be portion of the structure, as put in position, offered lever are bridge distributed, devised the following ,s secure against a hurricane as the finished bridge, itself as a staging for carrying operations further ahead, or afforded every means of suspending tempo- mud. The ground rises from the edge of the deep Leith Harbour and the shorter of Granton and water channel towards rary staging from it. The greater portion of the the shore with a gentle Newhaven, the roads full of shipping, the masses of work as erected could be securely fixed at once and slope, the clay disappearing about half-way up, and houses in the marine suburbs of Edinburgh, to of rivetted up, and this close up to places where new giving place ledges freestone rock. It will Arthur's Seat and Corstophine Tower just peeping was thus be seen that the natural of the over Mons Hill parts were in course of erection. Great rigidity configuration and the woods of Dalmeny Park. on the thereby insured, and less temporary work required ground centre line of the bridge, offers points To the south, the fertile districts of the Lr thians than in any other mode of construction, while it for three main supports, of which the two outer gradually rising to the imposing range of the IVnt- ones are about from land gave confidence to the workmen engaged, and equidistant the central one, Hills, and to south-west Dundas Hill
FIG. SA. LIVING MODEL ILLUSTRATING PRINCIPLE OF THE FORTH BRIDGE.
On three or four days during the year gales blow ; with such violence as to stop even large paddle boats from attempting the passage. On many other days the smaller barges and launches have to keep within shelter. During such times all outside work was necessarily stopped owing to the impos- sibility of handling material by the derrick cranes, or of getting about on the exposed stagings. From twenty-two to twenty-three full working days in the month must be considered very satisfactory in this climate on an hour or two ; many days only need have been lost but for heavy rains in the early hours, which drenched the men and sent them to their homes. When such happened no power of persuasion was great enough to bring them back to work again, even if the weather turned fine and con- tinued so for the rest of the day a curious fact not easy of explanation. Of snow there was but little during the seven winters, and but few days were lost through its covering the ground, but the frost caused much stoppage in a work where hydraulic appliances were so largely used, and where, owing to the enormous extent to which pipe leads had to be carried, it was impossible to effectively protect them all. It was thus the practice to break a number of joints and allow all pipes to drain dry after work stopped at night. Some of those joints were on deck, others on the very top of the structure, and a fire which occurred one night, February 13, 1889, on Inchgarvie spread to an alarming extent, and might have had most serious consequences to the lower portions of the steelwork as well as to the granite piers before the joints could be closed and the pumps made effective. The was all the danger greater that a furious gale was FlG. 1C. MAP OF THE FIRTH OF FORTH. blowing from the south-west, which made it a matter have come of some danger to get to the island at all, or when ing the bridge is the danger from sudden calms on Inchgarvie, where they would certainly have done con- there to ascend to the top of the superstructure to which frequently occur during spring tides when a to grief, but where they also might the find the broken joints. strong ebb is running, and which cause them to siderable injury to the structure in early days as three each consist- to for direction , of erection, timber booms, boom register any of wind. There order to ascertain, to some extent, how far great of three were moored was no made for ing heavy Oregon pine logs, provision registering intermediate , gusts of wind are quite local in their action, and to the west of Inchgarvie. The logs were octagon pressures, nor particulars as to direction of wind exert great pressure only upon a very limited area, ft. to 2 ft. in. about or section, from 2 across, and times of occurrence, except in so far as the two circular spaces one in the exact centre, and 100 ft. long, and were strongly bound together by records were taken generally at 9 a.m. every day. one in the right-hand top corner about 18 in. in three heavy iron belts to each boom. Mooring The principal gauge (Fig. 17) is a large board diameter, were cut out of the board, and circular blocks weighing nearly 40 tons each were laid down 20 ft. long by 15 ft. high, or 300 square feet area plates inserted which could register independently in the bed of the Firth, some 120 yards west to the set vertically with its faces east and west. The weight the force of the wind upon them. 1 booms. On the side of the island heavy iron stakes of this board is carried by two rods suspended By the side of this large square board, at a dis-
fixed in the to these or else to of i a so were rock, and some from framework surrounding the board, and tance of about 8 ft., another gauge a circular plate the iron columns, lj in. cable chains were attached. arranged as to offer as little resistance as possible of l square feet area, facing east and west was The other ends of these chains were shackled to the to the passage of the wind, in order not to create fixed up with separate registration. This was in- pointed ends of large floating buoys, and the same eddies near the edge of the board. In the hori- tended as a check upon the records given by the shackles received similar chains comingfrom the large ' zontal central axis of the board there are fixed two large board. mooring blocks. On the tops of the buoys were large pins, which fit into the lower eyes of the suspen- Another gauge of the same dimensions as the rings, and to these were attached the chain bridles sion-rods, the object being to balance the board as last, but with the disc attached to the short arm of from the ends of the floatingbooms, orratherfrom the nearly as possible. Each of the four corners of the a double vane, so that it should face the wind from
KgT) Id Fig.
Circular d/sc
tf/a'' square fett area
WIND GAUGES ON INCHGAKVIE. iron bolts near the ends. Sufficient slack was allowed TABLE No. I. RECORDS OF WIND GAUGES ON INCHGARVIE DURING VIOLENT GALES. in all chains for rise and fall of tide. These timber booms have been the means of saving many small boats and sailing schooners from certain shipwreck. With the calm weather in winter and early spring the sea fogs or eastern haars occu- with tolerable frequency, and have caused much anxiety on account of the necessity of having to carry large numbers of workmen many hundreds every morning and night from either shore to their destinations. These fogs come up the Firth like a solid wall of dazzlingly white cloud, sometimes leaving the tops of the towers standing out clearly in the sunshine, at other times hanging some 50 ft. to 100 ft. up in the air, and leaving the lower por- tions quite clear. The effect is well shown in the illustration from a photograph given on Plate XIII.
WIND PRESSURE AND WIND GAUGES.
The wind pressure to be provided for in the calcu- lations for bridges in exposed positions is 56 Ib. per square foot, according to the Board of Trade regula- tions, and this twice over the whole area of the girder surface exposed, the resistance to such pressure to be by deadweight in the structure alone. The most violent gales which have occurred during the construction of the Forth Bridge are given with the pressures recorded on the wind gauges in the annexed Table, No. I. It is worthy of observation that only one gale from easterly direction is recorded January 5, 1888 but there have been a number of gales from that quarter registering between 15 Ib. and 16 Ib. and up to 20 Ib. per square foot, and, of course, the same from other directions. The pressure gauges which were put up in the summer of 1882 on the top of the old castle on Inchgarvie, and from which daily records have been taken throughout, were of very simple construction. As the object was to ascertain only the maximum pressures which the structure would eventually have to resist, the maxima only were taken. The most unfavourable direction from which the wind pressure can strike the bridge is at right angles to the longitudinal axis, or nearly due east and west, and two out of the three gauges were fixed to face these directions, while a third was so arranged was in the case the only difference being that the vane is absent, other, the model or the cardboard sheet, whichever such additional support available of the and the of the base and P_i^ a fixture in R and cannot turn. The it may be, will be lagging behind, and twist the Inchgarvie pier, length has been doubled. The reasons for circular disc of course faces west. string. By now increasing or diminishing the area here nearly It is needless to say that these gauges were not of the cardboard sheet and repeating the experi- this are given further on. expected to give very accurate records of the wind ment ovej; and over again, a point will be reached The length of the cantilever bridge is 5,330 ft., of the central tower on pressures which occurred since they were put up, when the whole mass will swing without twisting consisting Inchgarvie, the cardboard will 260 ft. the Fife and central but they give a sufficiently approximate idea of being produced. The area of ; Queensferry towers, 145 ft. each the two central what the structure will hereafter have to encounter then represent the exact area of the model which ; connecting girders, ft. six cantilevers of 680 ft. each. in the way of wind. is affected by wind pressure. 350 each; and Upon one occasion the small fixed board appeared The experiments carried on in various ways by The cantilever end piers are apart 5,349 ft. 6 in. from centre to centre. South co register 6i> Ib. to the square foot, a registration different people and at different times are generally The Approach is ft. centre of cantilever which caused no little alarm and anxiety. Mr. in agreement with each other, and not very dif- Viaduct 1,978 long from end to end of of ten Baker, however, declined to accept the figures re- ferent from those arrived at by scientists witli most pier arches, consisting spans of 168 feet each four arches of 66 ft. each centre corded, and on investigation found that, with the complicated apparatus, and by laborious and pains- ; to abutments. lever multiplication-pointer, it was not difficult to taking processes. centre, and 34 ft. made up by The North Viaduct is 968 ft. in. obtain high figures, owing to the lever acquiring The points on which reliable information was Approach 3| long to end of five of 168 ft. momentum from a suddenly applied force such as a more particularly wanted were in respect of surfaces arches, consisting of spans and 46 ft. strong gust of wind would produce, thereby over- more or less sheltered by those immediately in long; three arches of 37 ft., 31 it., shooting the mark. Thus a blow of about 20 Ib. 'front of them. In the case of any box lattice centre to centre respectively, and 14 ft. 3 in. made abutments. The total of the applied smartly to the gauge would register 65 Ib., girder, for instance, assuming that the wind was up by length structure is therefore ft. 9 in. The two and would probably have registered more but that blowing fully square at it, it might also be assumed 8,2K> main are ft. from centre to centre of the pointer could go no further. This occurred in that the side nearest the wind would cover the side spans 1,710 and since the of the behind but if the wind blows vertical made of two cantilevers of January, 1884, then recording appa- girder lying ; columns, up ft. and one central 350 ft. ratus has been altered, the horizontal lever being at an angle to the girder, it is certain that the 680 each, girder to be crossed is done away with, and a vertical bar suspended second surface receives its proportion of full pres- The waterway about 5,700 ft., the wire of the substi- sure of the wind and in cases where two lattice box from the south circular on Fife to directly from gauge being ; extending piers at rail tuted. girders are close together as, for instance, in the Viaduct Pier No. 3 Queensferry. The level Since then the highest pressures recorded have top member all four surfaces will receive a pro- has been fixed at 157 ft. above high water, which been 35 Ib. 41 and Ib. amount of wind leaves for a total of 500 ft. in the centre of only , Ib., 27 respectively. portionate pressure. length each channel a clear of 151 no train A gale on March 31, 188C, gave the following It may easily be understood that the distance headway ft., load on the The load of results : from each other of these surfaces has a great deal being bridge. ordinary to do with the amount of wind stress receive, two trains is not expected to diminish this head- Upon the small fixed gauge 31 Ib. to the sq. ft. they and it was with a view of some useful more than about 3 in. ,, revolving ,, 20 ,, obtaining way by In the centre of the board The Fife and Piers are alike and large 28.J ,, data with regard to this question that Mr. Baker's Queensferry
, corner 22 identical in with upper ,, ,, ,, experiments were carried out. every respect, and only reversed All over the board 19 large ,, Information exists about flat surfaces and curved regard to their outer cantilevers. All six canti- levers are the in 680 ft. These figures seem to indicate that the higher surfaces, and also about cubes that is, two or same length namely, from wind pressures come more in gusts and sudden more sides of any rectangular box or girder upon centre of vertical columns to centre of endpost squalls than in a steady and even pressure extend- which the wind acts in a more or less diagonal and are also of the same height and width, namely, ing over a large area. direction. In all these Mr. Baker's experiments 330 ft. high at the central towers, by 120 ft. wide After the central towers had been carried up to agreed with those of other observers, and obtained at bottom, and 33 ft. wide at top, and 34 ft. high at the full two additional one with different but in the case of shel- the with a width of 32 ft. at bottom height, revolving gauges apparatus ; endposts, at the north-east and one at the south-west corner tered surfaces the results were somewhat different. and 22 ft. at top. The only difference in the can- of each tower were put up and records taken and On the whole, however, Mr. Baker satisfied him tilevers lies in the arrangements of the endposts, compared with those given by the other gauges. self that in no case was the area affected by the and further in the fact that the two outside or fixed The records confirm most distinctly the results of wind in any girder which had two or more surfaces cantilevers of Fife and Queensferry are somewhat the smaller gauges inserted upon the large board exposed more than 1.8 times the area of the sur- heavier in construction than the others. E ich can- for the pressures recorded vary as much as 10 Ib. face directly fronting the wind. As the calcula- tilever consists of a bottom member, or compres- and 12 Ib. between the different piers sometimes tions have been made for twice this area, the sion member, and a top member, or tension the one, sometimes the other, showing the higher stresses which the structure will receive from this member these being braced together vertically by registration. cause will be in all cases less than those provided six pairs of cross-bracings on each side, and being for. closed at one end by the vertical columns, at the EXPERIMENTS ON WIND STRESSES. Mr. Baker also tested models of girders built other end by endposts. The space occupied by The scanty information existing on the very of metal, both in air and in water, and although each pair of side-bracings is termed a bay, of which of six in important subject of the action wind pressure some slight differences with the former result were there are each cantilever. The bottom mem- surfaces of flat or are on the structures, whether found, yet 011 the whole they fully confirmed the bers connected together by twelve sets of hori- curved, induced Mr. Baker to make a series of general conclusions arrived at. zontal diagonal bracings intersecting in centre line, experiments, upon the results of which it would be The observations now made on the completed and further by the trestles and cross-girders, which to possible form some definite conclusions. These structure will no doubt help to throw further light carry the internal viaduct. The side bracings are so experiments interesting, and the appli- on this subject of great importance to engineers, connecting top and bottom members consist eacli ances by which they were obtained were so inge- since in large structures the wind stresses are of of a strut or compression member and a tie or nious, that no apology is needed for their repeti- considerably greater moment than the train loads, tension member intersecting one another, and tion here. Realising the difficulty of working and should therefore, for economical considerations, being connected at the intersections by strong with models in actual wind, which is never, so to be reduced to the narrowest limits compatible with gusset-plates and other stiffening. Each pair of of the same or direction for speak, intensity two absolute safety. opposite struts is connected by diagonal wind- consecutive moments, and under the both above and below the internal labouring GENERAL DESCRIPTION OP THE STRUCTURE. bracings viaduct, disadvantage of not having an instrument which and by a cross-girder at top between the top mem- Plate 1 to would reliably indicate the actual pressure at any (See III., Figs. 29). bers. From the intersection of struts and ties in time, Mr. Baker simply reversed the order of From the general view of the bridge in profile the sides of the cantilevers, lattice girders, called things by making the wind stationary and the it will be seen that it consists of two approach vertical ties, are carried downwards and attached to apparatus movable. The latter then consisted of a viaducts and of the cantilever bridge proper. The the bottom members, relieving the latter of deflec- wooden in the so as viaducts differ in extent the tion light rod, suspended middle, only ; height above between the junctions. Cross-sections of the to balance a from the water and the of the the cantilevers at of struts correctly, by string ceiling. lengths spans being same. each pair and each j air of At one end of the rod was attached a cardboard It will also be seen that a similar viaduct which vertical ties are given in Plate III., Figs. 11 to 29. model of the surface the resistance of which was to form's the railroad or permanent way is carried Each central tower is formed of four columns, be it a a flat- tested, be portion of round tube, a through the cantilevers and central towers at one each column resting on a circular granite pier. tened strut, a piece of top member, or of the uniform level. Transversely all these piers are 120 ft. from centre internal viaduct, or even of a whole cantilever. Commencing at the south end there are four to centre, or 60 ft. on each side of the centre line the On opposite end of the rod was placed a sheet granite masonry arches which terminate in the of the bridge. Longitudinally these piers are of cardboard facing the same way as the model, abutment for the South Approach Viaduct. Here 155 ft. apart from centre to centre in the Fife and so arranged that by means of another and adjust- the girder-spans commence 10 in number the Queensferry Piers, and 270 ft. in the Inchgarvie able sheet, which could slide in and out of the end of the last being supported in the south Pier. It follows that the central tower on Inch- the first, surface at that end could be increased or cantilever end pier. On the north shore there are garvie is much heavier in construction and different decreased at the will of the operator. three similar masonry arches, terminating in an in several features from the other two. The of mode working this contrivance is for a abutment, and five girder-spans to the north All the circular granite piers are carried to a to person pull it from its perpendicular position cantilever end pier. height of 18 ft. above high water, and the height towards himself, and then gently release it, being The bridge proper consists of three double between the centres of bottom members and top careful to allow both ends to If go together. this cantilevers and two central connecting girders. members is 330 ft., measured vertically, which is properly done, it is evident that the rod will Each double cantilever consists of a central tower gives an extreme height of the central towers above in retain a swinging position parallel to its original supported on four circular masonry piers a canti- high water of 361 ft. position, supposing that the model at one end and lever projecting from each side of it. The two The vertical columns so called for distinction the cardboard frame at the other end are balanced outside the Fife and in are vertical in one sense that look- piers Queensferry have, only ; is, when as to and that weight, the two surfaces exposed to addition to the four supports of their central ing broadside on. In the other sense, looking the air pressure coming against it in swinging are towers, a further support, inasmuch as their outer along the centre line of the bridge, they have an alike. Should one area be than the end inclination of about in exactly greater cantilevers rest in the cantilever piers. No 1 7, being apart, centre to ( 11 )
centre, 120 ft. at bottom and 33 ft. at top. This they are connected at bottom by the horizontal cantilevers is not archeci or curved, but polygonal batter of thu vertical columns is maintained through- portions of the bottom members, and at top by in form, each portion from junction to junction out the cantilever bridge. It had been intended those of the. top members, both of these being being a straight line and passing into the next to so arrange the sides of the cantilevers that the carried through in unbroken section. The four portion with a nick or kink. Apart from the fact batter of 1 in 7 in the central towers should corners of the rectangle thus formed are connected that a piece of straight tube is stronger than a bent gradually decrease until a vertical position was by a pair of diagonal struts intersecting each other one, some consideration was given to the manufac- attained in the endposts and the central girders; at the centre. ture of the plates for these tubes. Had they been but this plan would have led to considerable com- In order to facilitate the intersection these struts curved, nearly every plate on the circumference plications in the juncti/ms both in top and bottom and for similar reasons the struts in the canti- would have had to be shaped in a different die a members, and in the intersection of struts and ties, levers are flattened throughout on both sides, and difficulty still more increased by the decreasing and would have produced a twisted top member. at the points of intersection are considerably diameter of the tube from 12 ft. at the skewback There can be no doubt that the arrangement of stiffened and almost doubled in the plates. At to (i| ft. at the end of the fourth bay, after which a uniform batter throughout the structure adds this point a horizontal bracing girder is carried the member becomes gradually rectangular in form. materially to its appearance, by giving it harmo- across and attached to the vertical columns on The top member, being always in tension, is nious and simple lines, and heightens the impres- either side. In the case of the central tower on straight from the top of the vertical columns to the sion of stability and resistance to lateral wind Inchgarvie, owing to the greater distance between top of the endpost which closes the cantilever. pressure. the piers, the top and bottom members cannot be It is carried uninterruptedly through all the junc- The investigations and experiments made by carried for the whole distance without deflection, tions with struts and ties, though its cross section Mr. Baker, and extending over several years, have and a vertical tie is therefore brought down from decreases gradually towards the point of the canti-
. led to the decision that all members under compres- the intersection of the diagonal struts and attached lever. sive stress should be of tubular form circular by to the bottom member, while a vertical supporting The central connecting girder consists of a top preference where admissible this form being the column is carried up from the same point to take compression member, polygonal in form, and a or strongest, weight for weight. This rule is, for up the deflection in the top member. straight bottom tension member, with eight sets structural reasons, only departed from in the struts In tb.3 lateral sense at the base of the columns of vertical cross-bracings to each side, consisting of of Bay 6 of the cantilevers and in the struts and there are two horizontal bracing girders and one struts and ties, the struts being, as in the canti- top member of the central girders. All members pair (in the case of Inchgarvie two pairs) of hori- levers, provided with diagonal wind-bracings. The under tensile stress are open lattice girders. zontal diagonal bracing girders of great strength top members are also connected by sixteen sets of horizontal ii Thus the bottom members the vertical columns and stiffness, thus forming with the horizontal diagonal wind-bracings. From the points and the struts in cantilevers are always under com- bottom members a very rigid framework imme- of intersection of struts and ties a vertical lattice pression and are tubular in form, while the top diately over the circular masonry piers. A similar tie is brought down to carry the bottom member members, the inclined ties in cantilevers and double set of cross-bracings though of much midway between junctions. The bottom members vertical ties are invariably in tension, and are lighter section is placed at the level of the inter- are connected by solid plate girders going right of form. struts section of the thus these across these the rail and open lattice-girder The diagonal diagonal struts, bringing carrying troughs ; they in the central towers again, although always in com- points into direct connection with the four vertical are further stiffened by diagonal T bracings and by pression from dead load or wind pressure, receive columns half way up the towers. Between the the solid floor of buckle plates. an alternate tensile or compressive stress, and rice vertical columns are placed four sets of vertical The internal viaduct which carries the permanent rersA, according to the direction from which the live cross-bracings, the lowest of which also assist in way of a double line of rails and a footpath on each load or train load enters on the pier. In a similar carrying the internal viaduct at these points, and side, consists in the main of two lattice girders, set way the diagonal wind bracings between bottom horizontal bracings at top between the top members. 16 ft. apart, centre to centre, and of varying depth, members, the vertical columns and inclined struts in A similar bracing is placed between top members according to the length of span. Both top and cantilevers, are exposed to varying stresses according at the top of the central supporting columns and bottom booms are trough-shaped, the top booms to the direction of the wind, and they are likewise the vertical central ties on Inchgarvie above receiving the longitudinal sleeper and rails. A affected to some degree by the position of the sun. described. cross-bearing girder occurs about every 11 ft., and In order to preserve balance so far as dead All these members combined together form a upon this are laid the two inner rail-troughs, leaving load is concerned, it became necessary to load tower of immense strength and weight, well able the 6-ft. way between them. the ends of the outer or fixed cantilevers to the to take up and resist the enormous stresses resulting The main girders differ in their construction from extent of half the weight of a central girder. To from the combined influences of dead load, live those in the approach viaducts, in so far as they this end the endposts of these cantilevers are load, and wind pressure upon the tower itself and have vertical struts and diagonal ties. They are formed in a large box built of plates and filled with upon the cantilevers projecting from it. All these also continuous and without break from the end of dead weight to the required extent. Thus far then stresses, however, must ultimately resolve them- one cantilever through the central tower to the end the conditions would be alike for all six cantilevers selves in those portions immediately resting on the of the other cantilever. in the state of rest, and in the absence of wind circular masonry piers, which are called the skew- A footpath about 4 ft. 6 in. wide on the outside pressure and train load. Any introduction of the backs or main junctions. These junctions are the of each outer rail-trough is carried on brackets latter Would at once disturb the balance, and, gathering points of five tubular and five latticed attached to gussets both to the top and bottcm therefore, additional weight was placed in the girders, and as their construction will be described booms of the main girders. The footpaths are ends of the fixed cantilevers large enough to in detail further on, it is only necessary to mention formed by buckle plates, and buckle plates are also counterbalance any possible train load which is here that they terminate at foot in a flat plate fixed between tho rail-troughs and in the 6-ft. thus stiff likely to pass over the opposite end and leave called the upper bedplate, which is so arranged way, making up a very flooring. The a couple of hundred tons to the good. Under that it rests on, and, in some cases, can slide or bottom booms of the main girders are connected by these circumstances the ends of the free cantilevers move on another bedplate, the lower bedplate, horizontal cross-bracings. in the Fife and Queensferry Piers cannot deflect which is fixed to the masonry pier. It may be as well to mention that the footpaths except in so far as deflection is due to the elasticity The functions of these bedplates in resisting are to be used only by the railway officials. The of the steel. On the other hand the fixed end will and yet partially yielding to the wind-pressure and trains are intended to be run over the bridge at full receive a downward pressure of, in the case of the in taking up the expansions and contractions in the speed, and it would be neither convenient nor safe maximum, the weight of the counterpoise, plus the central towers are of so important a nature that to admit the general public. maximum train load, and in the case of the mini- they have received a very large amount of care and The girders of the internal viaduct are carried mum, the weight of the counterpoise minus the thought on the part of the engineers. The diffi- between the vertical columns (and in the case of the maximum train load, and of course any number of culties were avoided in the original design of Inchgarvie pier between the central vertical ties) by loads varying between the two. It will thus be seen Messrs. Fowler and Baker, and were consequent a plate-girder reaching right across, and by vertical how changeable are the conditions of load in the upon the modifications introduced by the other supports carried upwards from the intersection of cantilevers, and the stresses upon the different consulting engineers. the first pair of vertical wind-bracings between members. It had been the intention originally to make the columns. The same mode of supporting the In the central or Inchgarvie Pier the conditions skewbacks an absolute fixture upon the piers, after viaduct is adopted at the centres of the first and are different. There the weight of half a central having given an initial compressive stress to the second bays in cantilever*, while at the ends of the girder is carried at each end, and so far as dead load horizontal tubes between tho piers, also to clothe first, second, and third bays, as also at the centre of is concerned the balance is absolute. But every ton these tubes inside and outside with some non-con- tho third bay, trestles, supported by the bottom of train load introduced from either end will upset ducting material which would practically neutralise members, are arranged. At the centre of the fourth this balance at once, and it was therefore essential tho effects of heat or cold upon them. On re- bay a cross-girder carries the viaduct girders, and after the bottom to provide for every contingency. Tho worst con- consideration, however, it was decided to only fix this, member closely approaching dition that can be assumed would be for two trains one skewback out of the four comprised in each the line of the viaduct, similar cross girders; are used to meet in the central girder at one end. The pier, and to allow the other three to yield to a limited with short vertical supports. In bays fivs and six tendency would then be to form a fulcrum of the and well-defined degree to the influences of tem- the girders are absent, and the rail trough', stiffer in two nearest circular granite piers and lift the struc- perature, and to the lateral deflections produced section, are there carried by cross-girders and by the ture off the two furthest piers. As it was not in the cantilevers by wind pressure, and to some diagonal wind-bracings alternately. central intended that the anchorage in these piers, that is degree also by the heat of the sun. In the connecting girders the rail troughs, as are the holding-down bolts, should ever be brought into It suffices for the moment to say that, for various already mentioned, carried by solid plato- about 22 ft. play except under the most improbable conditions reasons, the south-east pier on Fife, the north-east girders every side of of hurricane pressure, it was necessary to make the pier on Inchgarvie, and the north-east pier on To each the internal viaduct a wind fence base of the central towers so great that the con- Queensferry, were chosen as the fixed points. The 4 ft. 6 in. high, and of lattice construction, is carried tingency stated above could not possibly arise. It arrangements of the bedplates, and the reasons for from end to end of the bridge, and on the approach is for these reasons that the central tower of the these arrangements, will be stated further on in viaducts. Inchgarvie pier has so much longer a base than connection with the provisions made for expansion The viaduct girders and rail troughs are rigidly either the Fife or Queensferry. and contraction in the main spans, and for distor- fixed to the cantilevers, and form an essential part The four vertical columns are combined together tions produced by wind pressures. of the latter, adding considerably to the stiiVncss ' and are braced in various ways. Longitudinally It will be noticed that the bottom member in the laterally of the bottom members. The only breaks occur at the and the made at the the correctness of the distances of junctions of cantilevers with the central estimated amounts, provision | possible, apart ! for the three stations on the centre lino of girders. The viaduct must therefore expand and our points mentioned longitudinal movement principal which had been obtained contract and move in every way with the cantilevers, s more than double that given above. the bridge, by calculation based the a measurement of and these movements will be considered presently. upon triangulation, It remains to mention the various influences to COMMENCEMENT OF WORK. the north span of 1700 ft. from the centre of the north circular on to the which the structure or portions of it are likely to piers Inchgarvie south the contract was in be exposed. Soon after signed December, circular piers on Fife was made in the summer of start was with the and 1. Expansion and contraction by changes of ^882, a made preparatory 1884. work. a of the British Rail- temperature, acting in the direction of the longitu- temporary In straight portion North Offices and stores as well as a hereafter ft. dinal axis of the bridge, and to some extent also workshop, way a distance of 1700 had been carefully mown as No. 1 had been erected Mr. measured transferred to transversely upon the circular masonry piers. shed, by and marked and high Arrol in connection with Sir Bouch's 2. Influence of the sun's rays to one side or the Thomas posts at the side of the cutting. Upon these posts other of the structure. suspension bridge, and these were taken possession notched knife-edges were placed at the two ex- of and added to from time to time. fine steel wire about in. in thick- 3. Wind pressure, acting at right angles or nearly considerably tremities. A J6 To enable the contractors to make start so to the centre line of the bridge. an early ness was laid along the span and drawn over the
with the that the of i a certain of Provisions for the first are made in the sliding as permanent work, is, building knife-edges with amount stress put
;he it was that the I Thus drawn distinguished from the fixed bedplates, in the masonry piers, necessary posi- upon it, previously agreed upon. up between the ends of cantilevers on tions of these should be fixed without delay. A the wire left a certain amount of in the joints Inchgarvie j sag centre, Pier, and in the cantilever end piers at Fife and Queensferry. Provisions for the second and third are made in the sliding bedplates of the two outer or fixed cantilevers, and in all the joints between ends of free cantilevers and central girders. All these movements are horizontal and are controlled and - confined within specified limite. The arrangements to meet these will bo described MS -.,.-i w. - ~~ .....nit: _ i in detail further on. The vertical deflections due to dead load, live load, and wind pressure, whether acting singly or in combination, have already to some extent been Fio. 19. EXPANSION DIAGRAM OF FORTH BRIDGE. described, and will be further considered later. Expansion joints are also provided in the ap- proach viaduct girders upon every second pier, two spans being made continuous, the intermediate fixed joints being, however, placed on sliding bed- plates identical with the movable ones. In the two large spans of the cantilever bridge, longitudinal movements are only possible at the Inchgarvie ends of the central girders, the Fife and Queensferry ends of the girders being fixed so far as this movement is concerned. These ends there- fore move with, and in the same direction as, the cantilevers upon which they are resting. It has already been stated that the south-east circular pier of Fife, the north-east on Inchgarvie, and the north-east on Queensferry, are the fixed points of the structure. The movements due to longitudinal expansion or contraction are controlled and limited by these fixed points, and extend from them as pivots to the various extremities of the cantilevers and central girders. The lengths affected are as follows. (See Fig. 19.) 1. The Fife central tower, 145 ft., plus outer or fixed cantilever, 680 ft., total, 825 ft. in length, the expansion of which must be provided for in the north cantilever end pier. 2. Fife south or free cantilever 680 ft., plus length of north central girder 350 ft., total 1030 ft., the expansion of which will go towards Inchgarvie, while the expansion of the Inchgarvie north canti- lever, 680 ft., will go towards Fife. The total amount of movement to be provided for at the Inchgarvie end of the north central girder where the two movements overlap, will be that due to the expansion of 1710 ft. of girders. 3. Inchgarvie central tower, 260 ft., plus Inch- garvie south cantilever, 680 ft., total 940 ft., the expansion of which will go towards Queensferry, 9S3SF while the south central girder 350 ft., and the Queensferry north cantilever 680 ft., make up a total of 1030 ft. the of which will length , expansion go towards Inchgarvie. The total movement at the Inchgarvie end of the south central girder where the two expansions overlap, is that due to a total length of 940 + 1030 = 1970 ft. Fio. 20. TEMPORARY STAGING ON INCHGARVIE. 4. The movement between the north piers on Queensferry and the south cantilever end pier is 825 ft. due to the same length as on Fife, namely base line about 4000 ft. in length was laid down which was carefully measured by level and noted. far as observations to this time have So up gone along the high ground on the south shore, starting Two narrow copper tags were then soldered on, to it that the or contraction would appear expansion from a point in the centre line of the bridge, pass- mark the end points. The wire was then coiled up for each amounts to about TJ th of an inch degree ing along the North British Railway for some dis- and kept ready for use. The temperature also of temperature for every 100 ft. of girder length. tance and terminating opposite the east breakwater was noted. in been so The changes temperature have, however, at Port Edgar. Along the breakwater a timber On the two shores immediately under the piers and so near mean that the slight, temperature gangway was erected, and near the far end of it, at which marked the stations, places had been pre- cannot be as distance of figures probably accepted quite a about 3000 ft. from the base line, an pared for levels, by means of which the amount of correct. observatory was built. Three points on the centre sag in the wire could be fixed. On a calm, cloudy for the moment their correctness, the line of the Assuming bridge, one on the Queensferry shore, day, with the temperature about the same, the movements would be, for 70 deg. of full range : one on Inchgarvie, and one on the Fife shore were wire was taken across the north channel and laid marked down, and their distances stated the down the on the 1. 3.61 in. by upon prepared knife-edges piers, Ordnance Survey of Great Britain. Various other and with the same amount of stress 2. 7.6 in. put upon it, stations, about twenty in were laid down and with the same amount of the two 3. 8.62 in. number, sag allowed, as required, and by means of these a most careful soldered on should have coincided with 4. 3.61 in. copper tags was made and the triangulation centres of the three the notches in the knife-edges, provided the dis- cent, of the main fixed. In to These figures only give about 70 per piers finally order verify, if tance was correct. It was, however, found somewhat short, and, embraces the four masonry supports of the Queens- designed for these works. The list of the plant on although carefully tried several times over, the ferry Pier. Extensions of this jetty were made the works towards the end of 1888 is a voluminous result did not vary. during the building of the foundations and Jower document, and is represented in the accounts by a Since the span has been completed the measure- portions of the approach viaduct piers, but were very large sum, not far short of half a million ments made along the girders have reduced the removed again after the girders had been completed. sterling; error to about 1 in. in the north span and (i in. A similar extension with landing stage for steam- Inchgarvie. The island of Inchgarvie, which Pro- in the south span, both being shorter than in- boats, and storage ground for building material was vidence has so kindly placed in the middle of the tended. The work of triangulation was carried made round the cantilever end pier, and remained Firth, is a peak of whinstone rock, about 850 ft. out by Mr. R. E. Middleton, M.I.C.E., and a full during the whole time. long at high, and 1500 ft. at low tide, and on record of his labours is given in a pamphlet pub- The jetty is built on piles driven in the silt and an average not more than 60 ft. wide above lished by E. and F. H. Spoil, London, about two soft clay down to the boulder clay. Where rock water. The castle stands on the highest part of years ago. occurs, the uprights are secured on level points by the rock about 40 ft. above high water, and the several reasons the of the four bolted to stout iron which are in is about 30 ft. on the of For positions being pins sunk square keep high ; top circular granite piers on Fife were first fixed, and holes drilled for the purpose. There are six piles this the wind gauges are fixed. The distance from soon the work there was in full swing. The greater mostly 12 in. by 12 in. baulks, set in a row trans- Inchgarvie to the Fife shore is about 1600 ft., while portion of the old coastguard station, which was versely, three on either side being bound together to the Queensferry shore it is rather more than situated on the site now occupied by the north-east by half-timber cross bracings on opposite sides and double. Although owned by the Dundas family, pier, had to be removed, and an entirely new station the whole connected by a full timber crownhead set whose seat is in Linlithgowshire, the authorities on built on the rock further to the north, and about on top. These trestles are set about 20 ft. apart, the north shore claim it as belonging to the County 40 ft. higher. The rock extending over the site of and are held together by raking struts passing from of Fife. the pier had to be levelled down to about 7 ft. above the top of one trestle to about low- water mark of the The castle was built some time subsequent to high water in order to obtain ground for laying next. Passing from trestle to trestle are 12 in. by 1490, on the 20th of March of which year, King down plant, machinery, and materials. The old 6 in. rolled joists about 25 ft. long, weighing 56 Ib. James IV. of Scotland granted a license to John the ancient for the to the lineal foot these are set 4 ft. to 5 ft. Dundas of to erect a fortress on the island battery slip, landing-place ferry ; from Dundas boats which slopes down from above high water to apart, according to position, and transversely on of Inchgarde, since corrupted to Inchgarvie. The a few feet above low water, was covered over with these the planking 3 in. or 4 in. thick, as the case object was to afford protection to all shipping seek- an extensive and substantial timber staging, on may be, is laid, which forms the flooring. The ing refuge from the pirates with which the North which cranes were erected for unloading and moving level of the top of the planking is about 8 ft. above Sea seems to have been infested in those days, and material, and which also served for landing the high water. The jetty was erected by means of an for giving such protection, Dundas was authorised workmen and for mooring barges and steamboats. ordinary traveller carrying an overhanging pile- to levy a toll of 6d. per ton. One of those persons (See Plates IX., XL, XII., and XIII.) Further driver, whicli set out the piles 20 ft. in advance without belief in the good old days has suggested inland, in convenient situations, wooden huts for and drove them in. The uprights were then cut to that the Laird of Dundas not only kept a garrison the accommodation of the workmen and their level, the crownhead set on, the diagonal bracings on Inchgarvie for the protection of the shipping, families were erected, to which were added, later on, and raking struts fixed, and the traveller moved but that he also provided the pirates in the North a and and forward on double for them the Firth with canteen, stores, dining reading-rooms. longitudinals. The joists were Sea chasing up ; though At South Queensferry the preparatory work was laid down behind the traveller and the flooring regard to this both history and charter are silent. of a much more extensive character. The ground made up. As this mode of working did not pro- The four circular piers are situated at the western here rises rapidly from the shore at agradientof about gress as quickly as desired, a pile-driving barge extremity, wholly submerged at high water, although 1 in 2 until it reaches an elevation of about 100 ft. was placed near the far end and worked towards a broad ledge of rock is uncovered by the tide at above the sea, and thence continues to rise with a the shore. In the position of the jetty forming low water. This portion of the island is called Craig gentle slope in a southerly direction. As a great the T head, the piles required to be very long, as Spurry, and upon its north-western point stands a deal of level ground was required here for work- the average depth at high water was about 32 ft. brick pier, about 33 ft. square, and about 7 ft. drill and for and the of soft or some 24 ft. re- above the of work shops, roads, spaces temporarily fitting depth mud silt, , high water, only piece permanent together portions of the steel-work, it became neces- quiring piles of from 65 ft. to 70 ft. in length, built in connection with Sir Thomas Bouch's gigantic sary to level the ground in terraces. Thus the spliced in the ordinary way. Pointed pile shoes suspension bridge. Upon it was erected, some three general level of No. 1 Shed is about 12 ft. below the made of malleable iron were fixed to the lower ends. years ago, a lighthouse with a revolving light giving offices, while No. 2 Shed is about 6 ft. above these, The shore end of the jetty was connected with the flashes about every five seconds, visible for many the drill roads another 5 ft. higher, and so on. under works by an inclined road laid on timber miles both up and down the Firth. No. 1 Shed was considerably enlarged, and No. 2 trestles, the gradient being about 1 in 6J, with an A spring of fresh water was said to have existed Shed at once commenced, as were also the drill iron girder bridge of about 65 ft. span across the on the island, and some 40 yards east of the castle, roads on which the tubular members had to be put Edinburgh-road. There was a single line of rails a square well, partly cut out of the solid rock, together and drilled. Further to the south still and a footpath to one side with a covered box run- partly formed by a brick wall, was found. It was some forty wooden huts were erected, together with ning alongside for carrying the hydraulic pressure pumped out and carefully examined, but no bore- stores for the sale of food and clothing, boots, and pipes, and also a supply of water down the jetty to hole or other inlet could be discovered, and it groceries, and a canteen with dining and reading- Queensferry Pier. The incline was worked by a proved to be simply a storage tank in which the rooms. wire rope, 1 in. in diameter, drawn by a winding rainwater from the overlying portions of the rock To these were presently added sixteen houses engine on the top. Down this incline all material collected. substantially built in bricks for the accommodation was sent which arrived by North British Railway, On Inchgarvie the first work in connection witli of foremen and members of the staff, and about whether fuel, oil, or other stores or plant and ma- the cantilever bridge was carried out in the sixty tenements at Queensferry for leading hands chinery, or, finally, steel-work which had been pre- erection, during the summer of 1882, of the wind and gangers. pared in the shops and yards. Upon the jetty itself gauges on the top of the castle, and already de- Next to the drill roads a carpenter's and joiner's a number of service lines were laid down with suffi- scribed. shop was erected with a saw-bench and a pattern cient room between, to store immense quantities of About the middle of April, 1883, the construction shop, and a large drawing loft, 200 ft. long by 60ft. building material. Along the east side two lines of a landing stage was commenced, of iron girders wide, with blackened floor upon which full-sized were laid down which conveyed all the material and iron columns pinned to the rock. At the same drawings were prepared and full-sized templates coming down the incline to three or four heavy time the square keep of the castle, some out- made for of steam which it into of were drilling, planing, bending, &c. , portions cranes, by was lowered the buildings, and the whole the battlements, of the superstructure. Telephonic communication the barges and conveyed to the landing stages on roofed in to afford space for the most necessary between offices, stores, workshops, and the Queens- Inchgarvie or Fife. While the jetty was in course shops, offices, and stores, to which was added later ferry, Inchgarvie, and Fife centres, was established of construction, launching ways were laid down in on, a substantial cottage and a kitchen, and sleeping by means of a cable laid across the Forth. a sheltered bay about a hundred yards to the east accommodation for ninety foreign workmen occu- On the west side, the ground was bounded by the below, and in front of, the sawmill. They consisted pied in the sinking of the pneumatic caissons. North British Railway to Queensferry, which here of parallel rows of timbers, of sufficient width to take All over the west end of the island, the rock runs in a deep cutting. Two temporary bridges two caissons of 70 ft. diameter side by side. They was cut down to the general stage-level of 7 ft. girders of the ill-fated Tay Bridge were thrown were laid to the natural slope of the ground, which above high water, and as much ground was made at across a distance of about 200 yards apart, and is here part rock, part shingle, and has an easy up as could be obtained, by filling up with the as the progress of the work required further exten- gradient of about 1 in 11. The launching ways will debris of excavation and of removal of rock sions, ground was taken on the other side of the be further referred to in connection with the build- Some 100 yards of sea-wall had to be built as a lines, until finally between 50 and 60 acres were ing of the caissons. protection against the heavy breakers rolling in occupied by the works on both sides of the line and Machinery and plant of every kind and descrip- from the east, and every square foot of space thus right up to the Edinburgh-road. All this ground tion commenced now to arrive on the ground. A gained was of great value thereafter, when an during the busy years of 1886 to 1889 was covered siding had been laid down from the works to South immense amount of material required to be stored. with girder- work under construction, and presented Queensferry station, about half a mile distant, and In the Act of Parliament authorising the erection a striking scene both day and night. another siding in the cutting alongside the shops. of the bridge, the whole of the island had been Down by the shore to the east of the central line Cranes were set up in all convenient positions, and included in the Parliamentary limits, but at first of the bridge a sawmill was erected, and later on a thus a large amount of material arriving by train only the area within the four circular masonry large cement store. The Queensferry jetty was could be unloaded close to, and distributed among piers, and a reasonable amount of ground for work- commenced early in 1883, and completed in the the different shops. By this arrangement the ing purposes was acquired. It was soon found that spring of 1884, shortly before the first caisson was various sections of raw steel whether plates, bars, this was quite insufficient for the requirements of launched. It is a little over 2100 ft. long, by 50 ft. angles, tees, or others could at once be delivered the works, and notice of compulsory purchase by the wide. It runs parallel with the centre line of the near the heating furnaces or drilling or planing ma- Forth Bridge Company, was given to the proprietor. bridge at a distance from it of 60 ft. to about chines where they required to be dealt with. The matter came to arbitration and was settled in 100 ft. beyond the cantilever end pier, whence it From this time forward for fully five years, the 1884. A sum of 1500L had been paid to the pro- passes by a gentle S curve right into the centre plant kept on increasing at an astounding rate, prietor for the right of placing four masonry supports line, and terminates in a strong crosshead which most of it being of a special character, and purposely on the island, and in terms of the arbitration a '(
the service of the workmen further sum of 2800L was paid. The island is now, to Kim, with which he made the bed into which the For general conveying or or the different main therefore, the property of the Forth Bridge Rail- column was lowered. It was then strutted by one from to, between, centres, steamer was hired for some which way Company. or two light battens to the already fixed work, a a paddle time, one built for It having been considered advisable to cover the 4-in. jumper lowered in the centre of the column, was afterwards replaced by specially and of 450 men at a whole area between the piers with staging, a com- and a hole jumped by means of a spring pole some these works, capable carrying tube time. The steam which were decked mencement was made without delay. Owing to 25 ft. long. The jumper was lowered through a barges, over, vised for the the nature of the bottom, which was all solid rock, 4J in. in diameter, which fitted into a socket left in the and the steam launches, were also same for the service of the it was found more expedient and safer in view of cast-ironshoe at thebottom, and acted as guide. The purpose, as well as engineers to this of hole about 3 ft. to 3 ft. 6 in. the and other officials to the staff. A large the exposed position, make staging iron, was jumped deep ; belonging boats were also in and not of timber. The arai of this staging ulti- jumper was then withdrawn, and a wrought-iron pin, number of ordinary rowing kept two mately amounted to more than 10,000 square yards, 4 in. in diameter and 5 ft. long was dropped down use, one of them, manned by expert watermen, for the and the weight of iron used in its construction was the tube. The latter was then lifted up, and the being attached to each cantilever purpose unfortunate between 1100 and 1200 tons. In view of this large diver descended to ascertain whether the pin had of saving life, should any man be to fall the erection. As a matter of expenditure for temporary purposes, it was deemed well entered into the rock. When the columns enough from fact these boats saved at least and right to proceed on some system in the laying out were fast, a length of girder was laid upon them on eight lives, they saved 8000 other which the main line of girders. As the horizontal each side, and the crane advanced another section. fully caps and garments tubes, the horizontal girders between skewbacks, Across the longitudinal girders, 12-in. rolled joists the wind had blown off the bridge. and the double cross of diagonal horizontal wind- weighing 50 Ib. to the lineal foot were laid, being Soon after the works had got into full swing it was seen that the accommodation at South bracing, required to be carried by the staging before 21 ft. to 25 ft. in length, and therefore overhanging Queens- the they could be connected with the skewbacks and the girders from 3 ft. to 5 ft. The joists were ferry and North Queensferry and adjoining for the number of rivected up, the main lines of the iron girders of bolted to the girders by hook bolts and ordinary villages, was totally inadequate were made the staging followed the centre lines of these draw-washers, and were spaced 5 ft. apart. The workmen employed, and arrangements to run members, the remaining spaces being filled in decking consisted of 3 in. by 9 in. planking, bolted with the North British Railway Company bolts trains the works on the south side and sufficiently strong to carry any weight which was to the top flanges of the rolled joists by and between and between the north side and Inver- likely to be put upon them during the erection of draw-washers from underneath. Edinburgh, were all the superstructure. As this staging stood well the The staging, as first projected, was commenced in keithing and Dunfermline. These special very severe tests to which it was subjected from the autumn of 1883 and finished before the end of workmen's trains and were run at merely nominal various causes, and only yielded to a slight extent 1884, but additions became necessary from time to fares, the price for an Edinburgh weekly ticket being in places where it had been absurdly overloaded, time to accommodate the immense quantities of 2s., or 2d. for a run of over 13 miles. The Dun- half that it may not be amiss to give a few particulars as to material, and at times the 10,000 square yards of fermline tickets were about amount. its construction, shown in Fig. 20. staging were found quite inadequate to meet the Two trains were run in the morning, closely The upright columns or supports consisted of demands upon it. following one another, and two trains at night, each four 4 in. 4 in. in. braced All of the which had to be used as train a number of men on their angle-bars by by f , together portions staging bringing going on all four sides by double crossbars of flat section, landing places for materials and of such there were shift, and taking back those who had worked their later the train service 3 in. by in., the column being 2 ft. square. A a good many had the iron columns strengthened shift. Some time was cast-iron shoe, to which the four corner angles were by bolting on heavy timbers, with half-timber extended as far as Leith. It is worthy of remark bolted, formed the foot of the column, and it had a fendering upon that for wear and tear. Horizontal that the men living at Leith, and there were several large boss in the centre with a 4 in. round hole timber struts were also set up against the backs of hundreds, had to leave their homes at 4 A.M., in a into the rock those columns to in order to be at their work at and would not through which pin was passed going , guard them against bending 6, they to a depth of about 3 ft. by the action of the boats and barges upon them in on their return in the evening, reach home again The longitudinal main girders were 5 ft. in depth, rough weather. before 7 o'clock, yet they preferred this to the and consisted of four angles 6 in. by 4 in. by \ in., By the time the staging was up round the north other alternative of living in the overcrowded two in the bottom boom and two in the top boom, piers on Inchgarvie these were already well for- rookeries of the neighbourhood. with gussets inserted between every 5 ft. apart for ward arrangements had to be made for the re- In the summer time a steamboat service was also attaching the diagonal bracings, which were angles ception of the two heavy caissons for the south arranged between the South Queensferry Jetty 6 in. by 3 in. by \ in. placed alternately on one piers. Facing the south, therefore, two semi- and Leith, via the Firth of Forth, calling both ways side or the other. The girders were carried by, and circular openings were left about 73 ft. in diameter, on Inchgarvie, and so long as the weather was bolted to, cross-angles attached to the supporting an extra number of columns were placed in the favourable, this was a most enjoyable, and certainly columns. The girders carried safely a distributed half-circle and well braced with the others next healthy trip for the tired workmen. load of about 6 cwt. to 7 cwt. per square foot up to behind, and the whole row of columns between the On wet and stormy days, when the men had to 30 ft. clear span between supports. The columns north and south piers, on either side, were joined leave work owing to the weather, these trains were were arranged in clusters of four, forming a square, together at about low- water mark by a continuous often telegraphed for, to enable them to return to the sides of which were 14 ft. taken at the centres of line of double angles to take the thrust from and their homes, instead of keeping them till nightfall columns, and such clusters were placed immediately give resistance to any possible bumping of the and leaving them to the tender mercies of the public- under the points of intersection in the girders of the heavy caissons during the time they required to houses, of which there were in this place, as in structure overhead, or in fact in any place where remain afloat. many others, far too many. much weight had to be carried. The four columns so Meanwhile plant and machinery were sent here As it was not possible to so arrange that the work- r placed w ere braced to each other by crosses of flat as to the other centres, a number of offices, large men living on the south side or north side of the bars of heavy section 3J in. wide by 1 in. thick, the workshops, stores and shelters for the men were Firth respectively, should be working on the same centre of the cross formed a built also for and as the also to being by heavy ring, ; engine-houses pumping engines, side, Inchgarvie men belonged the flat bars terminating at that point in 1| in. air compressors, hydraulic accumulators, electric both sides, it required quite a fleet of steam- round with a thread cut upon them which passed into light machinery, and much more. boats and barges to convey the men to the the ring. By a nut on either side of the ring the points whence their trains started, the more so TRANSPORT AND DISTRIBUTION OP MATERIAL. flat bar the other end of which was bolted across as this had to be done within a very short tiniu the column could be tightened or slackened as The supply, the transport, and the distribution of after work had ceased. In bad weather, or the desired. Two or three sets of these bracings, materials necessary for thebuildingof foundations during fogs, and on dark mornings and nights according to the length of column, were bolted to and piers containing some 140, 000 yards of masonry the transport of many hundreds of men some nine each of the four sides of the cluster, the lower ones and also of some 55,000 tons of steel, and a more hundred working on Inchgarvie alone at one time reaching in most cases to within a foot-or two of the than equal amount of temporary appliances, was no was a subject of unceasing care and anxiety to those bottom of the column having to be put on by divers. mean task, and required the exercise of much in charge, for in addition to the dangers provided by Generally speaking these clusters were placed about energy and skill as well as tact and patience, for the elements, there was always a number of unruly to intermediate the work every 45 ft., centre centre, and for was equally pressing on all points, and no and reckless men whose conduct brought mishap supports, where necessary, single columns under one liked to be left behind in that great race for and injury on others as often as on themselves. each girder were considered sufficient, and these supremacy. would receive transversely a pair of angle-iron cross- Of the building materials, granite, Arbroath LIGHTING. and bracings between high-water and low-water mark. rubble, sand were brought by water, and could, The efficient lighting of so large a working The longitudinal girders run through the uprights, therefore, be unloaded at the various centres where area, changing every day almost, having not only 14 ft. and were braced so also could rafts of spaced apart, they laterally required ; timber in baulks to be carried forward with the work, but also about every 25 ft. by a pair of cross-angle bracings and planks or battens in barges, and in some Upward and in all directions, was a task of con- to boom instances of carried from top boom on one side bottom cargoes coal or coke, but all the other siderable magnitude, and of the greatest influence on the other side and vice rersd. material had to come down the incline, and for upon the rate of progress. It is not so much the of these the All the girders were made in regular lengths jetty at Queensferry was the main centre lighting of the actual spot where work is proceeding, at 5 ft. were marked of and as well as of bars, breaking joint ; they by collecting storing, distributing but that of the approaches to these points, and of and and all those for to the other template punched, parts except jetties. the accessory places, such as stores, engine-houses, were All holes were The steel for after it closing lengths interchangeable. erection, had passed through workshops, jetties, and landing-places, which runs for bolts. The the and had received a of punched J-in. girders weighed just shops coating boiled oil, away with so large a proportion of the total illumi- cwt. foot all 1 the and its both in 1| per lineal, including bracing: ., distinguishing markings typing and nating power. columns about 64 Ib. foot bolts. was incline per lineal, including stencilling, passed down the on trollies As regards the nature of the lights it was to be The whole was erected with and into steam for staging by overhang charged barges general distri- expected that a keen rivalry would spring up be- derrick cranes in the : from a bution. following way Starting tween the various systems of lighting. South the next columns forward would be lowered For the service of materials were cluster, carrying pro- Queensferry has only a small supply of gas, and that till they nearly touched the ground, the diver vided, four steam launches for the and at the ruinous rate of 8s. 4d. cubic feet light work, per 1000 ; would then descend and examine the select- steam with a of bottom, eight large barge?, number ordinary this mode of lighting was therefore out of the a level bit, or otherwise the rock or which ing nearly dressing barges lighters, were towed by one of the race. Electricity was at ones resolved upon -arc A few of concrete were then lowered launches or ba^s barges. lamps for the shops, and outdoor work, and incan- 15 \ )
' but if with a descent lamps for offices, stores, fitting-shops, and excellent light to work by, covered number of hands were kept going to attend to the of such like. The latter were also used in the caissons fine wire guard or a second globe the power the lamps, the dynamo machines, the cables, and other and by divers under water, and proved of immense light is seriously impaired, and if left unprotected, connections. The conductors varied in size from 7 value in such work. The incandescent lamps were the smallest chip of metal, or even of wood, throwr strands of No. 18 gauge wire to 19 strands of No.
but within the last suffices to cause fracture to the ant 16 ; were generally of 15 candle-power, against it, globe gauge they supplied by Messrs. W. T. to 500 candles were extinction of the Glover and Co. of Salford. few years, lamps with power up light. , in where the work is con used for particular purposes. Except special cases, to fined to a small the writer has MATERIALS OF CONSTRUCTION FOR THE MASONI-.Y The arc lights were of 1500 2000 candle-power, comparatively area, in in work of outside PIERS. and though every care was used to obtain the best no hesitation saying that, the It was laid carbons in the market and to keep the machinery erection, under the best conditions of lighting, anc down in the specification to the con- were with care taken to the men confidence that all and going with the utmost regularity, these lights every give tract, piers, abutments, arches were to in in about their the amount of work done be constructed of of always unsatisfactory owing to the changes the getting job, masonry consisting a granioe colour of the arc and the illuminating power, the at night will not exceed 50 per cent, of that done facing, the hearting being of concrete or of rubble in As a of the o The as to the glare and flicker and the black and impenetrable daylight. consequence lighting masonry. stipulations quality of the the amount of shadows thrown by their own framework or by any the piers at various points and heights, and changing stone, facing and dressing, and the to circumstances of cement and intervening object. Generally they were arranged these almost nightly, according quality -sand, were of the usual in circuit of six or more, and sometimes as many as there arose a great deal of confusion to the shipping description in contracts of this kind. and it must be Granite. All for twenty-one, and the sudden extinction of so many going down or coming up the Firth, the, granite facing whether trivial that a dark for some rock-faced or dressed was obtained lights caused by the comparatively fact of a conceded on night, when, from Aberdeen, or not carried on with the of the belt slipping or a journal heating, was a source of reason other, work was upon exception large coping-stones, which between 6 tons inconvenience and much danger to the men working one of the main piers, it was difficult at the first weighed and 8J tons each, and the courses out on the erection, for while standing one moment glance to know the exact position of all the piers necking immediately below the coping. the These were of Cornish in the dazzling glare of these lights they were On such a night, with a slight mist on, captain granite and were dressed. with in The is in colour sometimes suddenly called upon to use their eyes of a tug-boat, coming down river a barque granite grey generally, and of in absolute darkness or sit still. tow, mistook the lights on the Fife erection for very handsome appearance, with some slight veins his of red Where the electric light came in as a great and those of Inchgarvie, and steered ship straight granite running through, which, however, which rather add than detract from its lasting boon was in the lighting of the interior of for the hamlet of North Queensferry, was appearance. / The was the air chambers and air shafts of the large pneu- hidden in the mist. He perceived his error in time granite brought, roughly dressed and in matic caissons while in the process of sinking. The to back his boat out and slip the tow-rope, but the squared, specified courses ranging from 21 in. in thickness to absence of all smoke or filth due to oil lamps of barque continued its course and did considerable down 16 in., and also specified as It is headers and so as to form whatever description, the facility with which they damage to itself and to the landing jetty. stretchers, proper bond with the hearting of rubble masonry or concrete. INCH-BARVIE N.W. IKON COFFER-DAN. Coming by water, the stone could, of course, Section through Shield. be delivered at the respective centres at once. The granite were 4 ft. 6 in. in showing node of making joint to /?oc* coping-stones depth, not less than 3 ft. in width, and set out E temp.'Coissw alternately as headers and stretchers. The capping that is, the slightly-curved crown of the piers- was set out after the coping had been built, and the correct measure of every stone was sent to the quarry near Aberdeen, each stone being numbered and marked. Eubble Work. For this a very hard flat-bedded and easily-split freestone in colour from reddish ochre to purple grey was brought from Arbroath. It was brought in large blocks up to 4 tons each, and in thiekness from 3ft. downwards, but it could be split with ease into slabs not more than an inch thick. Whinstone blocks, roughly levelled on two sides, were also used in rubble work. These were ob- tained either by quarrying in the open or by the excavations for the piers. , For bond courses m all the viaduct and the canti- lever end piers, a hard freestone from quarries in the neighbourhood or extra large whinstone blocks were used. All the rubble could be obtained at a cheap rate, to the owing inexpensive mode of transport in shipa and the facilities of unloading close to the piers. Concrete. For making concrete the whinstone found both on Inchgarvie and at North Queens- ferry was exclusively used. A number of stone- breakers were set up in the last-named locality, where a large quantity of quarry chips were avail- able and close at hand, and the crushers were placed in convenient positions for charging the INCH-SARVIf. IKON COFFER-DAM. N W. PIE.K. broken stone into barges or iron skips for transport Outside view of Shield. to the other centres. BEARING OP CAISSONS ON ROCK FOUNDATIONS. The broken metal w?J passed over screens to obtain the required size for different could be or purposes. moved, changed, put up taken down, i true that a glance at his compass would have shown The concrete was mixed was of dry first, and again after incalculable advantage in places where him that a course instead of an the northerly easterly addition of water, either hand, or, if re- even the air was a by breathing purest task of some could not be right; but it was in of in discomfort and consequence quired very large quantities, by a very effective difficulty, and here, the this that it was decided to therefore, mishap erect a light- mixer of simple construction. electric light reigned supreme. house at the north-west corner of Inchgarvie with The concrete used in in the From the drawbacks mentioned above open foundations, which a revolving light giving five-second flashes. This laissons and as behind the attached to the electric hearting granite facing, arc lights, the is at an elevation of about 30 ft. Lucigen light above high differed somewhat in its composition to lamps, which were also introduced at an according early water, and can easily be seen for twelve miles but were up position ; generally speaking the proportion of period, entirely free, though their short- and down river. cement to broken stone was not less than 4| cubic comings cannot be overlooked. There can be no As the cost of regards lighting, it was not easy :eet to the yard of stone, nor more than cubic doubt that for work of erection 6| general they are under the peculiar circumstances of on the 'eet to the an of or the best carrying yard, equal amount sand, a for light, the simplest to in work at the to keep order,, bridge make comparative trials excess over and added. These and the easiest to slight above, being attend to. The of the At first the balance disadvantages lights. was much in quantities were considered as one yard are that are difficult to as a making up they , favour keep clean, good of the Lucigeiis the oil costing only id to of concrete. Such concrete had a resistance to deal ol the oil ! escapes unconsumed, especially in d. but as the demand rose so per gallon, did crushing of 50 tons per square foot, and it high winds, and covers and with weighed girders staging a the cost of the oil, and it was difficult about cwt. j 37 to the cubic ick coat of ultimately yard. slimy oil, them to it at v making slippery obtain four times the original price i o)irf. Some was in ob- and unsafe It difficulty experienced is also difficult to get the creosote Electric of light installations, consisting steam- :aining good sharp sand. It was found in large 'il pure and tree from and which sand, grit, water, engines and dynamos, as well as air compressors for, runntities on both shores of the Firth within half a impurities cause the small for the oil to ! passages the Lucigen lights, were put on the Fife but to its removal raised while the up shore, uile, objections being by choke, ast frequently extinguishes the"! at on the Inchgarvie, Queensferry Jetty, and at the he proprietors of the foreshores, it became neces- light. On the other hand,' it is as shifted as the easily workshops above, latter being, of course, by ary to send steam barges down the Firth to an arc lamp, and is not so or nearly fragile apt to far the most important. and a distance of ten be broken. inghorn Pettycur, to eleven the busiest the During years lighting arrange- niles, where the tide lay some banks dry at low Large incandescent lamps give a steady and most ments a and a required separate department, large yater. Owing to the barge having to be grounded DETAILS OF SOUTH APPROACH PIERS.
Pig. 23. Inside. View. 25. Cross Section. Section in centre, line, of _V .. S-7' B" Kg. Fig.WB. Bridge,
Cantilever Side/ t^OT^gLpS^JIp
. 24- . Section A B & Plan
over a tide, a good deal of time was lost, but there was no charge for the sand. WATER. Fife. On the Fife shore the water required was drawn from the mains of the Dunfermliiie, Aber- and Burntisland water but this dour, supply ; sup- ply becoming scarce, the contractors were obliged to construct a storcge tank above North Queens- ferry. Inchgarvie. As already stated, no water was found on Inchgarvie, and, after some trials with condensers and niters, it was decided to use the lower 5 ft. of the holds of two of the steam barges as water-tanks. A large water-tank was set up on Inchgarvie, and the water was forced from the holds of the steam barges into the tank by means of pulsometers, the latter being worked by the steam of the barges' boilers. The water was taken from either the North Queensferry or South Queensferry supply, and this work was generally Drinking water was supplied to the people on performed during the night by one or two barges, Inchgarvie in iron boxes encased in wood, holding there being thus a steamboat available all night in about a cubic yard the water being always taken ' case of emergencies, from the Dunfermline mains for this purpose. South On the south shore the I a sieve of 400 meshes but ! Queensferry. through retained upon hillside was commenced somewhat later at level 92 ft. water was drawn from the pits of the Dalmeny one of 900 meshes to the square inch divisions above water. All the (20 | high piers on the Fife side Shale Works for boilers and other and 30 divisions to the lineal general pur- inch). About 10 are founded on the solid whinstone rock, with the it too and some cent, of ; but water had to be poses proved dirty, rough per added, and briquettes exception of piers 12 and 13, these on 1 _ 1 _l_ _ j. 1. _ , , being partly filter-beds of had to be constructed to : which were to be into gravel pass made, put water after twenty- whinstone, partly on freestone. All the viaduct it Thence it was forced to an four hours and remain in water through. by pumps | twenty-five days, piers being on land no cutwaters were built. The overhead tank set about 00 ft. above the level of when had they to bear a stress of not less than rock after being cleaned and examined, and worked tlie works and This water was conducted 170 Ib. without For of neat shops. breaking. briquettes roughly into steps where necessary, was levelled up in down the incline to the in cement the pipes jetty, and, breaking stress after four days had to with concrete and a bed of concrete laid on from 4 ft. various lends, all over the works. For be not less than 300 Ib. and after seven to to 11 ft. in drinking , days thickness this bed projecting all round another from the sand- be not less than 400 Ib. purposes supply pumped per square inch. the granite masonry some 2 ft. Upon this con- stone was but it inter- A few tons of or available; proved very quick-setting Roman cement crete foundation the first course of granite was set, and at times failed In the were used in the of mittent, altogether. making good joints the circular the form of the piers being rectangular and the summers of 1886 and 1887 a water famine occurred iron cofferdams or caissons for the Inchgarvie curved batter of the pier starting from the bed. at South and this was met the north This is Queensferry, by piers. cement not very strong, but (See Plate VIII.) Piers 10, 11, 12 and 13 were contractors iron tanks at the town if the are well with of built to placing large joints packed bags clay level 37 ft. above high water, and left, harbour and a steam down the Firth and loaded with stones sending barge puddle they answer the pending the construction of the girders. to a place called Starleyburn, seven miles away, purpose of keeping the water out for a while. If where a plentiful supply of water could be got. all preparations are made beforehand, Roman GENERALLY ABOUT COFFERDAMS. This was forced into the and could be drawn cement can used tanks, be in a plastic state, and is thus In the description of the pier foundations, all free of In 1887 the united useful to divers under water but all is upon by charge. very working ; frequent use made of the terms caisson and of parishes Kirkliston, Dalmeny, and South the work requires to be done very quickly. cofferdam, and to those not conversant with for a of water from Mortar. Queensferry arranged supply The mortar used in the masonry was in foundation work in water a short explanation the Pentland and this new is both the Hills, supply proportion of one of cement and one of sand in may be acceptable. A cofferdam or caisson may and of first-rate and has been the plentiful quality, foundations, where rubble-work was used, and be described as an enclosure in water for the pur- since the summer of 188T. one of cement to two of sand in running the piers. The pose of laying dry the space enclosed, or, at any pointing in the of the blocks was done of a flow of water it. In CEMENT. joints granite rate, preventing through in pure cement. soft ground this is done by driving a double row of The cement used was Portland exclusively Of the other materials used, except the steel, it piles at a distance of from 2 ft. to 4 ft. from each cement manufactured on the This be as well to Medway. may state here that timber in baulk other, and by continuing to drive piles between those also came but to be stored for a was by water, required brought from Grangemouth, ten miles up river, already placed until a double timber wall exists all
FIG. 31. RAFT USED FCK SURVEY OF FOUNDATIONS.
Sluice doors or valves are so as to specified number of days before it could be used. where it was rafted and towed to the works round. placed" out. timber The contractors purchased an old hulk called wherever required. allow the tide to flow in and The single while in its prime the Hougomont in which ten Planks, battens, and boards were brought from piles are held together by longitudinal timbers being each side and bolted and or to twelve hundred tons could be readily stored. the same place in lighters. placed on through, stays the walls across the It was moored off Queensferry, and the ships Hardwood, such as oak, beech, and ash, used for stints are placed between and directions to stiffness and bringing cement from the south were moored packings andother temporary purposes, was got in inner space in all give from without. The alongside and discharged. From this ship the the neighbourhood and dealt with at the saw-mills. resistance to the water pressure walls is now cleaned out cement was brought ashore and stored in such Coal and coke for the three main piers were space between the double well as can be and is filled into quantities as might be required at any time. brought in barges mostly from Charleston, close as done, clay puddle the was moored close but for the and were this and trodden down hard or down Subsequently Hougomont by ; shops yards they brought space pressed other and this is carried on until the to the west side of the South Queensferry jetty, by rail. by means, or and thus a more direct and speedy communication Creosote oil for the Lucigen lamps, and rivet and whole space is filled up to and beyond half tide full tide as the case be. The sluices can then established. While the caissons were being sunk other furnaces, came in specially constructed tanks may out from the at Queensferry a large number of foreign workmen by rail. be closed and the water pumped the founda- were lodged on board this hulk, and when, shortly enclosure, and the bottom upon which COMMENCEMENT OF THE PERMANENT WORK. be and all after new year, 1886, an epidemic of small-pox tion is to be placed can examined, broke out at Queensferry, the ship was towed round The positions of the four main piers on Fife being necessary excavation made. It depends partly upon of the into Port Edgar, and moored in an isolated position, fixed at an early date, a beginning was made with the the hold the piles have taken ground, partly forces the timber- and converted into a small-pox hospital. As such excavation of the rock upon the site of the two upon the external acting upon and waves whether or not the it proved of signal service in speedily stamping out north piers. The natural bedrock of whinstone rose walls namely wind the disease. here to a level of from 10 ft. to 20 ft. above high water, construction of a whole tide dam is advisable. In Cement Tests. The cement is described in the and excavation had to be made to the level at which a whole tide dam, if tight at bottom, when once the or bolts has been the work of excavation specification to the contract as having to be of the the foundation holding-down started water pumped out, ft. foundation and a or best quality and ground so fine that the residue on namely, at 7 below high water. The rock was of laying the building pier without to the a sieve containing 50 divisions on the inch, equal then levelled with rubble masonry and the building wall can be carried on interruption the to 2500 meshes per square inch, should not exceed of the granite courses commenced. end. In the case of a half-tide dam, space after the tide out- 5 per cent, by weight. It had to be kept in a dry Excavation was also started upon the site of the enclosed can only be pumped dry level of the store, and was not to be used until a certain north cantilever pier at a level of about 21 ft. above side has fallen below the clay puddle the water to be admitted so soon number of samples out of every cargo had been high water, and upon viaduct piers, 10 and 1.1, at wall, and requires to that tested. Neat cement was not to be set within less 25 ft. and 22 ft. above high water respectively. as the tide has turned and is rising again up half-tide dam is termed tidal than one hour. The weight had to be between These three piers stand on high ground, while piers level. AVork in a on rock this mode of 112 Ib. and 116 Ib. per bushel. 12 and 13 were placed at the bottom of the ancient work. "When working forming is not For tests, the cement to be mixed with three quarry, and were founded at level 7 ft. below high an enclosed space by driving piles admissible, means must be found to the vater times its weight of sand which has been passed water. The foundations of the abutment upon the ai d o'her keep
B one of which will be described below. In some second row was next laid outside of caused the action of waves to out, | A round the by heavy running tip cases, whether working upon soft ground or rock, it the first row, and tolerably close up, the space the caisson at low water with great j temporary is not absolutely necessary to lay the bottom dry in between the two being made up by clay puddle violence, and shaking the whole fabric. to or to the the latter order excavate inspect ground well stamped down. Any split, or hole, or crevice The whole of the north-east pier was built in a of the being done by means divers and former in the rock was also filled with clay. Upon these half-tide caisson, as the work was not pressing; or otherwise. The of such a dam two lower other were now laid crosswise but in the case of the north-west so soon as by dredging object rows, bags ; pier, is to arrest the flow of any current through the upon these, two rows lengthwise, and a fourth row the rubble masonry inside had been brought up to caisson while the foundation is being laid, and to crosswise on the top, which was laid close up to the low-water level, a second tier of temporary caisson deposit the material of which the foundation is to belt. This was done in sections of about 15 ft. to 16 ft. was added, and the work could then be carried on consist most generally concrete by lowering it length all along the shield, but round the outside of at all states of the tide. While tidal work was through the water in boxes or skips, the bottoms of the treble belt only two bags deep were laid. On the carried on in these two cofferdams, the amount which are provided with hinged doors. inside also a single row of clay bags, backed by a of water which had to be pumped out every tide Finally, if instead of a caisson open at top, the row of concrete bags and loaded with stones, was was 250,000 gallons in the one case, and 340,000 in caisson is covered in like a bell or gasholder, and the laid round the complete circle. Cement grout, the other. The time occupied was 50 to 55 minutes, water is forced out by forcing air in, thereby allow- without intermixture with sand, was now prepared but work was, of course, commenced so soon as the ing the workmen to enter and excavate in the dry, and passed down to the diver but only at slack higher parts were laid dry. For pumping out it is called a caisson worked by the pneumatic pro- tide, high water, or low water who lifted off one smaller quantities of water collected through leaks, cess. In this manner the deep-water foundations of or more of the top bags and poured the grout into pulsometers or small centrifugal pumps were used. the circular piers were executed, as will hereafter be the narrow space left, until it overflowed. He then The temporary caisson is shown in Plate VII. described, in the case of the two south piers, Inch- replaced the bag and proceeded to the next division A statement of the time occupied in building the garvie, and the four Queensferry circular piers. until all was done. Forty-eight hours were allowed foundations of thesetwopiers is given inTableNo. II. INCHOARVIE NORTH CIRCULAR PIERS. TABLE No. II. PROGRESS OP WORK ON INCHGARVIE PIERS. On Inchgarvio the site of the two north or shallow piers being wholly submerged at high water, and about one-half in the case of the North-East Caisson. North-West Caisson. north-east, and three-fourths in the case of the north-west pier, submerged also at low water, the work was tidal, and between preliminary Rock excavation commenced ...... June 22, 1883 January 13, 1884 tides no work could be carried on at all at spring Lowest point of foundations 26 ft. below high water 33 ft. below high water this When it is considered how place. exposed Caisson and shield ready for lowering February 29, 1884 September 10, 1884 the position was there the work having to be Joint between caisson and rock made good .. . April 2, 1884 October 17, 1884 carried on upon a narrow ledge of rock attacked Caisson pumped out first time... April 5, 1884 October 20, 1884 wind and waves from all sides it will be by Rubble masonry in foundation commenced... April 16, 1884 October 24, 1814 understood that the progress could not be very Foundation finished to low water June 1, 1884 December 20, 1884 rapid. The conditions of the contract here required First granite laid June 2, 1884 December 23, 1884 that the rock should be excavated in and steps, Pier completed ...... November, 17 1884 March 18, 1885 that the rubble masonry comprising the foundation of the circular granite piers should be bound by an iron belt 60 ft. in diameter and 3 ft. deep; the of to for the of the cement the sluice FIFE SOUTH CIRCULAR PIERS. highest portion the rock upon which this belt elapse setting ; rested to be 2 ft. below low water valve was then and the caisson As the two south on Fife were also situated ; the belt, or at closed, pumped piers leaks were the oil the face of the and excava- any rate a part of it, to be brought down to form a out gradually. When discovered, sloping rock, required tion at different a somewhat similar course protection for the foundation rubble masonry upon diver descended to examine the outside, and, where depths, was followed in the construction of the cofferdams or the lower steps. necessary, cut out some of the grouting and replaced It was therefore decided to cut a chase 8 ft. wide it by new. caissons, but with one important difference. In the (3 ft. to the inside and 5 ft. to the outside of the As it was not considered that this cement joint case of Inchgarvie the caissons were set on the rock, full of and secured to as far as 60-ft. circle) out of the rock where it was higher would be able to stand the pressure the it, possible, by weight- than 2 ft. below low water, to make the 60-ft. belt tide rise, the caisson or cofferdam was worked as ing them, and the joint was made good previous to it to out of rock near the 60-ft. circle of three thicknesses of ^-in. plate, and to carry the a half-tide one, having be pumped every any blasting being so far as the excavation of the circular centre plate downwards, after it had been cut, in tide as soon as the water had fallen below the top done, except caisson. In addition to the chase was concerned while in the case of the Fife such manner as to fit as nearly as possible the edge of the temporary ; to south under a sub- natural contour of the rock. (Fig. 21.) A light hydrostatic water pressure, the caisson had stand piers, diamond-drilling plant contract was to drill all over the area of staging was, therefore, erected above high water, the heavy seas thrown against it, whether coming employed from west or east. Under these it the and blast the rock before cofferdam the correct centre of the pier placed upon it, and by circumstances, pier any or caisson this means of a trammel-rod 30 ft. in length, from the was often considered advisable not to pump out the had been put down. For work an end of which a pointed sounding-rod was suspended, cofferdam, but leave the sluices open and allow the iron girder staging was erected over the piers, on with end to a correct reading was taken every 6 in. on the cir- tidal flow free access. Under such conditions, it which a traveller running gear from to the different cumference of the 60-ft. circle, after a diver had will be easy to see that, during a season of bad end was placed. The depths which in the excavation had to be carried was been round to clear out any loose stones lying in weather, much delay could not be avoided, and steps given, holes drilled to these a the line, or picking off any sharp points projecting. though the work of excavation had been commenced and depths. When number till of holes were were with These readings were plotted and the centre plates in the summer of 1883, it was not the middle ready, they charged explo- that the first rubble sive and fired but the rock was not removed at the cut to it. In the mean time work had been done of April of the following year ; upon the chase, and, when nearly cut down to masonry could be laid in this pier. In working the time, and lay there in great shattered masses. 1 ft. was that it the right level, the belt was put together on the excavation, no blasting was done within of The consequence when was attempted rock to to caissons with shields to fit the staging exactly above the site of the pier. The the iron belt, but the was quarried up place projecting in contour of the the leaks were of such a nature plates projecting downward, and forming the shield, within 6 in. and rubble then built at once. Any rock, to at were stiffened by T bars vertically over the butts, steps cut in the deeper portion were invariably at as defy any pumping power then hand. and, where required to be carried down to a con- least twice as broad as they were deep. The deepest The Fife south-west pier, in which the deepest siderable depth, as in the case of the north-west point to which excavation had to be carried in this part was 7 ft. below low water, and in which only water. a small below the level of the pier, they were further stiffened by horizontal pier was at 8 ft. below low very portion lay 2 ft. circular girders and stayed to the rock by bars of The cofferdam or caisson for the north-west pier, circular chase below low water, could be was done in the same as with some little but in the angle-iron. The whole belt was now rivetted up, Inchgarvie, way precisely managed difficulty ; the shield and, when ready, received two coats of red-lead described for the north-east, only that, owing to south-east pier, where had to be carried the divers and other to 19 ft. below low it to jwiint, and was lowered down by means of hydraulic the experience gained by men water, became necessary of jacks into position. (Fig. 22.) engaged upon the work, the progress was much construct a puddle clay dam round the outside The top edge of the 3-ft. belt was then levelled more rapid. the caisson with piles heavily shod and driven into of the debris of all round, and corrected where necessary. A heavy In the north-west pier the depth the shield broken rock. Even then the difficulty angle iron, 6 in. by 6 in. by Jin., ran round the was 15 ft. below low water, and extended to nearly could only be overcome by collecting together the a of of inside of the 3-ft. belt, and upon this was now set a one-half of the circumference. There were, there- water from number leaks, and by means single tier of temporary caisson, 10 ft. in height, and fore, in addition to the vertical T bars which powerful pumping machinery to get the upper hand consisting of fourteen segments of about 30 cwt. each covered the butt-joints of the shield -plates, three of it. Rubble masonry was then built in all places carried a in weight. This helped to keep the belt down to the horizontal circular girders, at distance of where running water could be kept off, and the rock, and a number of heavy blocks of stone were 4 ft. 6 in. from each other, and from these a leaks were thus gradually hemmed in, and finally placed on the top of the caisson for the same pur- number of horizontal tie-bars with cross-bars at stopped by pouring cement grout into these places pose. A sluice door in the lower part of the the ends were carried radially and level to the at slack water and with the sluices open, in order that caisson was kept open to admit of the tide flowing rock opposite and pinned to it, and afterwards no water might be forced through the grouting in and out. built into the solid rubble masonry. (See Fig. 22.) before it had set. Steps were now taken to make good the joint This mode of making the joint between the rock A largo diving bell, with air-lock and the neces- between the 3 ft. belt and the shield and and the iron belt was simple and quite effective. sary machinery to move the bell all over the area of the bedrock. This was done in the following Most of the leaks were due to natural crevices in these piers, had been constructed, as it had been j ' manner: A number of concrete bags, about 14 in. the rock, running from the inside to the outside at intended to form the foundations of concrete depo- sited by 30 in., and 8 in. to 9 in. thick, were prepared a considerable depth. These were circumvented by through the water by hopper-bottomed skips; and passed down to a diver, who laid them round building small clay dams round, and leading the but as it was subsequently decided to have the the outside of the belt at a distance of about 4 in. 1 water by a shoot to a pump. Lc^ks were also foundations of rubble masonry instead, it became is) ( )
for the necessary to lay the bottom dry, and the diving strength, base upon which this grea bell was never made use of. masonry pier had to be raised was not less thar The north piers on Inchgarvie and the south 115 ft. long by 00 ft. wide. It was at first dividec piers on Fife are founded on the solid whinstono into halves by a double row of piles wit] after a o rock. puddle clay filling ; but, good portion had laid all side Tablo III., given below, shows the time occu- the concrete base been round the pied in building the foundations of the four circular of the dam, this partition was cut down, the pile off flush with piers on Fife, the depth to which the foundations being sawn the bottom and the con were carried, and other particulars. crete base carried right across. In this pier th<
TABLE No. III. PROGRESS OP WORK ON THE FOUR CIRCULAR FIFE PIEUS.
FIFE CIRCULAR GRANITE PIERS.
North- West. Korth-East. South-West. South-East.
Excavation commenced August, 1883. Feb., 1884. August, 1883. Nov., 1883. h.w. below h.w. 26ft. belowh.w. ft. below h.w Lowest point of foundations ... 7ft. below 7ft. 37 Rubble masonry in foundation menced Nov., 1883 March, 1884 June, 1884 March, 1885 Foundation finished to low water Nov., 1883 April, 1884 June, 1884 May, 1885 First granite laid Dec., 1883 April, 1884 June, 1884 June, 1885 Pier completed Sept., 1884 Sept., 1884 Jan., 1885 August, 1885
PIERS. SOUTH APPROACH VIADUCT boulder clay at bottom was found nearly dry anc On the South Queensferry shore the founda- extremely tough to handle, and it gave an indica- tions of piers 3, 4, and 5 were first started, as tion of the ground into which the large caissons they were all dry at low water. These three would have to be sunk. piers are founded on the freestone rock prevalent Table IV., given below, shows the levels at which in ridges all along this shore. Tidal work had the foundations were started of all the viaduct piers to be resorted to without any protection by from 1 to 9, of the south cantilever pier, the north cofferdam or caisson, and all that was required cantilever pier, and the abutment, as also the nature was to remove the soft or rotten portions of of the ground under foundations. the rock and cut flat steps into any sloping Figs. 23 to 28 show views of the cantilever enc faces met with. The hollows were then levelled pier and the viaduct piers, with the principal dimen- up with concrete, and upon this a concrete base sions. The cutwaters with a coping of dresscc was laid enclosed by planking. When this had granite reach to the same height above high water set the at once as the circular 18 and to this properly granite masonry was piers, mmely ft., up begun. The concrete base was Cl ft. long by 31 ft. level all the piers from 3 to 9 were built with a wide, and was the same for all viaduct piers from hearting of concrete; above this level the granite 3 to 9. The thickness of this concrete foundation was backed by masonry of Arbroath rubble in varied according to position, from 4 ft. in the shore cement carried up to the top. The hearting in piers
TABLE No. IV. PARTICULARS OF FOUNDATIONS FOR VIADUCT AND CANTILEVER PIERS, AND NATURE OF GROUND.
For General View of THE PNEUMATIC CATSSONS ; QUEENSFERRY.
6l'\. 8"-
' Half"'Section 'on line 0. D. Fig. 33. the centre being always fixed by the two theodolites east, south, and south-west, with heavy cable chains wetted, and at once filled into bags. About twenty- reading angles from fixed stations. The whole area attached, the ends of which were temporarily secured six of these went to a yard, and they were put into a for about 40 ft. or 50 ft. round the two caissons was to the staging. Two stout wire hawsers were also boxes with hinged bottom and lowered down by thus sounded, and a very fair idea of the contour of prepared to pass round the caissons as soon as they steam crane and emptied. They were put together of feet of had the bottom obtained. About 3000 soundings were would be placed in position. by a diver, and, when a couple pier thus taken, representing a large amount of work and To hold the caissons with some amount of security been built, a number of sandbags of much larger trouble with the sounding gear, the mooring chains, when once they would take the ground, and give size were put all round it to keep it in place and the cement. the winches, and last, though not least, with them a good bearing all round the edge, it had prevent the tide from washing out rough weather, and distortions thereby produced been decided to place a large number of sandbags When the concrete piers had been completed, in the raft itself. upon the rock, and bring these up to the same level the remaining space under the cutting edge was or three The raft was also used for fixing the guide piles and somewhat above even as the highest point laid with sandbags, except in two places or columns against which the caissons would come of rock the cutting edge of the caisson would be where channels were left through which the air which also the sand- to lie, and, as a precautionary measure, the centre likely to touch. In order to still more securely fix this could escape, and through the was set 1 ft. up the slope of the rock, as it was bed of sandbags, two rectangular piers were built up bags and other debris could be pushed down tolerably certain that during the sinking operations first of bags filled with concrete, and these were rock during the sinking of the caissons. In two the and near where the caisson would slide away from the newly cut placed (see Figs. 29 & 30) opposite the highest point places well within air-chamber, face. of the rock on the circumference of the 70-ft. circle. the centre of the caisson would come to be, two As soon as the soundings had been taken, and the The concrete was of good strength, there being 27 piers of sandbags were built up upon which the guide columns fixed for the reception of the caissons, cubic feet of stone to 4 cubic feet of cement and ceiling of the air-chamber would be supported. blocks laid It remained now to down the for the heavy mooring were down to the south- , 4A cubic feet of sand. It was mixed dry, slightly lay pipes THE PNEUMATIC CAISSONS; QUEENSFERRY.
Plan on line 8. B (!? Q~ Plan on line A A.
supply of air and water, and the electric light cular piers, and to some extent outside and round quadruple piles were placed on three sides of the cables for immediate connection with the caissons it, a number of soundings were taken to ascer- space left. As the tide currents are not nearly so tain of as soon as they should be moored in place. the depth of water, of mud, silt, of soft strong here as on Inchgarvie, and as the caissons clay, and of hard clay. These data are given in would almost immediately touch the soft ground another The head of the which had low the of their PRELIMINARY WORK IN CONNECTION WITH TUB place. T jetty, during water, danger getting away in the mean time been left four was much less here, and no outside were FOUR QUEENSFERRY CAISSONS. completed, moorings corner spaces free for the reception of the cais- therefore provided, but strong chains fixed to the Over the area to be occupied by these four cir- sons, and strong timber dolphins of treble and piles, and ready to be attached to lugs rivetted to the caissons, and stout ropes and wire hawsers to terminated with the cylindrical portion. To make bottom, forming the flanges. Two of these shafts of pass round them, were kept in readiness. up for the loss of strength a circular plate girder were used for the removal of the debris excava- Air compressors, electric light machinery, over- about 2 ft. 8 in. deep is carried right round at this tion, the other for the ingress and egress of the head water tanks, pumps to supply the same, place, similar girders being placed at the second workmen. In the Queensferry caissons the shafts of the steam cranes, and other plant, were got ready, and plate joint below, and at every second plate joint were pretty evenly distributed over the area large quantities of broken stone, cement, and sand above, all these circular girders being combined by working chamber, the reason being that in these were stored close by for use. Water pressure at vertical angles about every 6 ft. on the circum- caissons, as soon as they touched ground, work 1000 Ib. per square inch was brought down the ference. (See Fig. 36.) could be carried on all over the area at once. In incline from the accumulator on the top, and con- ducted to the end of the jetty. Tlie Pneumatic Caissons. The six caissons which were sunk by the pneumatic process were mainly built of wrought iron, and were in the first instance constructed and put together by Messrs. Arrol Brothers, of Glasgow namesakes, but otherwise in no way connected with Messrs. W. Arrol and Co., of Dalmarnock Iron Works, Glasgow. These caissons were taken to pieces again and sent to Queensferry to be built up and rivetted, as here- after described. Description of the Caissons. The four caissons of the Queensferry group are all of one design, differ- ing only in height. There are two shells, carried up at distances varying from 7 ft. at bottom to 4 ft. 6 in. at top from each other. (See Figs. 32, 33, 34, 35.) The two Inchgarvie caissons, although externally the same in appearance, differ in so far as the inner shell is only earned up as far as the top of the cylindrical portion, being replaced above that by a backing of Staffordshire blue bricks built in cement, which was carried up in proportion as the caisson was sunk below low water. (See Fig. 36.) Generally speaking, the caissons are made up of two parts the cylindrical and the taper part. The cylindrical portion is of varying height, with a slight taper upwards to facilitate the sinking. This por- tion is 70 ft. in diameter, and above it is the taper part, which is 24 ft. high in all cases, and terminates with a diameter of 60 ft. at top. The lower, or so-called cutting edge of the caisson, is stiffened by a stout double angle and by u broad steel belt, 18 in. wide, and 1 in. in thickness. At a height of 7 ft. above the cutting edge an air-tight floor is formed which extended over the whole area up to the outer skin or shell. From this floor upwards, started the inner shell of the caisson, about 56 ft. in diameter; and here also, but downwards, started the sloping plates, which terminated at the cutting edge, and which were backed and held by a number of triangular brackets set against the floor to one side and against the outer shell to the other. A circular space of tri- angular section was thereby formed, access to which was had by manholes cut into the floor between every two brackets. Under the floor a space was thus left of the form of a truncated cone 70 ft. at bottom, 56 ft. at top, and 7 ft. in height, which was called the air-chamber or working chamber. Its function was to act as a diving-bell for the purpose of gaining access to the bottom of the river and carrying on the necessary excavation over the area thus made accessible. The triangular space sur- rounding the air-chamber was called the shoe, of which the lowest part, as already said, formed the cutting edge. The roof of the air-chamber was supported by four strong lattice girders 18 ft. in height, and reaching from side to side of the inner shell, but being carried through to the outer shell by means Fio. 36. SECTION OF CAISSON AT INCHOARVIE. of bulkheads or plate diaphragms set between the two shells, and rivetted through with the end posts of the large girders. At right angles to these latter were carried plate girders 3 ft. deep, and spaced 4 ft. apart, centre to centre, all over the ceiling of the air-chamber. The floor plates were so arranged that their joints, where it could be done, were butted immediately under the centres of these girders, the bottom flanges of which acted as covers on one side, while there were covering flats on the other side. Between the shells, the stiffening was obtained by circular lattice girders, which consisted of angle rings attached to both the inner and outer shell at every plate joint, and of angle bars set radially and attached to the angle rings by gusset plates, and also by inclined angle struts which passed from the angle ring attached to the inner shell to the next Fio. 37. CAISSON AND CRADLE ON LAUNCHING WAYS. higher ring attached to the outer shell. The top of the caisson was of a formed horizontal circular Three holes about 3 ft. 7 in. in diameter were cut the case of the Inchgarvie caissons, only two shafts plate girder upon which the temporary caisson was into the ceiling of the air-chamber at convenient one for men and one for material were used, and set and bolted the down, joint being made by india- distances, and here were inserted three air-shafts, these shafts were close together at one side, because rubber about 1 in. in cording diameter. the lower edge projecting into the air-chamber most of the work there had, owing to the sloping As the inner shell in already stated, the Inch- about 6 in. They were made up of lengths of face of the rock, to be carried on near the point caissons was not carried to garvie up the top, but 8ft. each, with an angle hoop rivetted on at top and where the cutting edge first touched the rock. In addition to the a number of cast-iron cradle was loaded air-shafts, with pieces of iron to hold it put on and all necessary mach'nery placed inside, were from the air-chamber down to the before pipes fixed, reaching launching ways when the water lifted they were removed to the r p jrmanent places. ceiling to various parts of the outer shell, and these the caisson oft' its bearings and floated it away. This was done, not only because it was essential that were used for the removal of silt and soft The of the these caissons material, slope launching ways being about 1 in should touch ground as soon as pos- all of which, in combination with water, were 11, it required a push from a 12-in. hydraulic sible after their arrival in their berths, but also ejected by means of a small quantity of compressed jack, placed horizontally, to set the mass in motion, because a large proportion of the machinery inside air being allowed to escape. and this it did most effectually on all occasions. and of the temporary caissons, was taken from the the difference be- In the air-chamber itself, main The launching of these caissons took place Queensferry piers, then already built up to above tween the and caissons con- at or Queensferry Inchgarvie generally near to the time of high water ol high water, and put on board, and the transport sisted in a different arrangement of the shoe. spring tides, owing mainly to the shallowness oi and double handling thus saved. It may not be In the former, the sloping plates were carried the shore in front of the launching ways the amiss to state, as an instance, that the last caisson right down to the cutting edge, while in the latter caissons drawing from 9 ft. 6 in. to 10 ft. 6 in. ol No. 6, or south-west Inchgarvie was launched they only went half-way down the slope, being then water at the time. As soon as afloat a tug-boat on May 29, 1885, weighing a little over 500 tons, bent in a horizontal direction, and brought to the was attached and the floating monster at once with a draught of 10 it. 3 in., was towed to Inch- outside shell and then rivetted on. For the sup- towed to its final resting-place, or else to the end garvie on July 16, drawing 31 ft. of water, and port of the lower remaining portion of the outer of the jetty, where convenienc >s existed for weighing 2877 tons, which was made up as fol- shell, strong brackets were fixed about 3 ft. 6 in. charging concrete into it and placing all the neces- lows: apart on the circumference, and these terminated sary machinery on board, as also the temporary Tons. Permanent caisson at the lowest angle, which, with the 18-in. steel caisson on top. Should any tide not rise as much 457 caisson 65 belt, formed the cutting edge of the caisson. This as was expected, it was the practice to hermetically Temporary (two tiers) was done in order to allow the sinkers the fullest seal the air-shafts and other outlets from the Two air-locks, air-shafts, concrete mixer, boiler, steam &c. 35 access to the rock immediately under the cutting working chamber and force air into the latter, in crane, Timber floors and edge, it being of the greatest importance that it order to increase the buoyancy. staging 50 should be undercut to the extent of at least 6 in. first caisson Concrete 1418 The that for the south-west pier, nil round. of is Brickwork ...... 852 The section the Inchgarvie shoe Queensferry was launched on Ma> 26, 1884, the shown in Fig. 52. ceremony being performed by the Countess of Aber- Total It has already been stated that launching ways deen, the Earl being at the time Lord High 2877 .vere laid down on the south shore to the east of the Commissioner to the General in Edin- Assembly Before entering upon the description of the mode ' These timbers were laid on the The last caisson was jetty. (Fig. 37) burgh. launched on May 29, of sinking the caissons, some account is needed to natural of the holes at 1885 the south-west slope ground, being dug Inchgarvie. be given of the apparatus and machinery in con- intervals which were filled with and up concrete, nection with that part of the work. thus provided strong piers to carry the weight of the AIR COMPRESSORS. caissons. At the higher end of the timbers several trestles were set transversely, of such height as to There was nothing in these different from any keep the work out of the reach of the water. The ordinary type of compressors. They consisted of a tops of the trestles formed the platform upon pair of horizontal engines coupled, and directly which the construction of the caisson was com- acting upon a pair of double-acting air-compressing menced and carried 011 until about 25 ft. or 30 ft. cylinders. There were two pairs of 16J-in. cylinders of it, counting from the lower edge upwards, had with 2-ft. stroke, and three pairs of 12-in. cylinders been built. The weight was then about 300 with2-ft. stroke, all working at 60 Ib. steam pressure. tons. By means of hydraulic jacks the caisson was They were run up to any speed required to produce then slightly raised and packed, and the trestles the necessary maximum pressure, which in the case ol withdrawn. It was then lowered down to within Inchgarvie on one occasion amounted to 37 Ib. per half a foot of the top of the launching cradle. This square inch in the air-chamber of the south-west was made up of transverse girders laid on longi- caisson. The air-compressing cylinders were water- tudinal timbers, which in their turn were laid on jacketted, with a continuous current of cold water the timbers forming the launching ways. The top passing through. For the service of the rock drills of the cradle was, of course, horizontal, and it was inside the working chamber, a separate engine was essential to support on it as large a portion of the used, which forced air down by a separate pipe lead ceiling of the air-chamber as could be reached, and at 70 Ib. per square inch the rock drills receiving, also as much as possible of the lower or cutting of course, the benefit of the difference between that edge of the caisson, which latter was also supported pressure and the prevailing one in the air-chamber for the time being by a number of timber blocks only, as they had to discharge into the general placed on the ground. pressure of the working chamber. On the top of the men's air-lock a whistle was set BUILDING OF THE CAISSONS. which worked by air pressure and which could be In the building of the caissons, the general prac- regulated from below; by means of this a constant tice was to commence by laying down the bottom communication was kept up, and more or less air booms of the large lattice girders upon the timber pressure put on in accordance with requirements. trestles at the head of the launching ways, to bolt U33C3 The pipes supplying the air were laid from the the 3-ft. cross-girders between them, and fix to compressors straight to the caisson side, but the AIR-LOCKS. both the floor-pistes. Outside the trestles, any joint to the pipes inside the caissons had to be made projecting parts of the caissons were supported from by a long piece of flexible tube, the end of which the ground by timbers. The plates forming the The Temporary Caissons. The temporary cais- was attached to a check valve placed upon the air- inner shell were next put on, and also the sloping sons, placed on the top of the permanent ones for lock for the admission of the men. The air was plates forming the shoe, the two forming one joint the purpose of keeping the water out while the forced down this shaft into the working chamber, with the floor-plates. All joints were rivetted up circular granite pier was being built, were of the thus preventing the ascent of any foul air in these as far as possible by ordinary hydraulic rivetters, same construction as already described in connec- parts. and meanwhile the bracings of the big girders were tion with the Inchgarvie north piers. (See Figs. 32 A supply of water for flushing purposes was also put on and the top booms laid on these, and more and 51.) The lower tier of caisson segments, in laid on, being taken from an overhead tank set plates were added to the inner and outer shells. addition to the large number of small bolts which about 40 ft. above the level of the staging. 1 I pon the girders the first platform was laid down, made the water-tight joint, had two long 2-in. bolts Of great importance both for the safety and con- and a hand crane set up as well as forges, concrete to each section of caisson, or twenty-eight bolts on venience of the men, and for the progress of the mixer, and other gear. By the time the caisson the circumference. These bolts terminated at top work, were the air-locks. Those by which access was about 25 ft. high much of the lower work in a screw thread with nuts, and at bottom in a long was got to, and exit from, the air-chamber, consisted being then done it was got ready for lowering, as shackle, which grasped a lug rivetted to the out- of an inner portion, 3 ft. 6 in. in diameter, in con- already described. It was even then still accessible side of the permanent caisson. The temporary cais- tinuation of the ascending shaft, and a circular space in the lowest portions soon after half-tide for son was made large enough to allow space round all round it about 21 in. wide and 6 ft. high. (See further work and for making preparations for the completed pier for the masons pointing the Figs. 38 and 39.) The outer chamber was divided by launching. Previous to this, all joints in the plates joints in the granite blocks. Two tiers of caisson two partitions into two equal spaces. Each of these forming the ceiling the sloping face of the shoe total height, 20 ft. were generally held sufficient to spaces was provided with a square door giving com- and the outside shell of the caisson were out the water but in where munication on the one side to the carefully keep ; places rough seas air-shaft, and on the caulked to make a good water-tight job. and much spray were likely to occur, a third tier, or other side to the outeratmosphere. All doors opened In all cases, previous to launching a caisson, the at any rate a portion of it, was put on. The south- ;o the inside. To gain admission to the air-chamber shoe and the whole space over the ceiling of the east caisson on Inchgarvie had a special temporary it was necessary to enter one of the outer spaces, to filled air-chamber were up with concrete, the latter caisson constructed for it, consisting of plates 22 ft. close the door (which was pressed against an india- gjnerally to a depth of from 4 ft. to G ft. This not in length. (See Figs. 36 and 53.) rubber joint), and by turning a small cock to o.ily acted as ballast, but it gave much stiffness to The four Queensferry caissons, after being gradually admit compressed air. As soon as the all the lower portion of the caisson, and produced launched, were at once towed out and placed in pressure on both sides of the door leading into the a draught of from 9 ft. to 10 ft. after it floated. their proper positions, being secured to the jetty air-shaft was equal, this latter fell open and the ait- When finally the caisson had been built to the in such a manner as to allow their rising and falling chamber could be reached by an iron ladder fixed re juired height and weight, all the points of con- freely with the tide. The Inchgarvie caissons, on n the shaft. To return from the air-chamber to tact batween cradle and caisson were carefully the contrary, were merely placed in a temporary ;he outside was the reverse of this, the pressure aljuste.l, and all the weight allowed to rest on berth near the end of the jetty, and they were Tom the outer chamber being exhausted by opening the cradle, it being then ready to be launched. The :ompleted there, and had the temporary caissons i small cock communicating vith the atmosphere. r-_w-- o as .s w ^ EC 13 j o .a ^fDOCsSM3)^5 3
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s-^aS O9 hJs o: o 3 AIR-LOCK AND HOISTING GEAR FOR CAISSONS.
set up near the lock so as to centre the air-shaft with its the door of the lock was then heaving chain ; top drawn back and the skip or bucket, about 3 ft. in diameter and 4 ft. high, holding about 1 cubic yard, was lowered down into the lock and the shackle of the inside winding chain attached to it. The upper door was now closed, and a slight turn of the engines tightened the chain and lifted the bucket just clear of the lower door. A cock, or valve, which communicated with the compressed air in the working chamber, was now opened and pressure thus admitted to the lock. The sliding doors were provided with india-rubber joints, and small thumbs or tappets, actuated by a lever, were used to force the door hard up against the india-rubber, in addition to which the gradually increasing air pressure helped to close the joint. When the upper door was thus secured, a turn of the inter- door free this w;:s locking wheels set the lower ; now drawn back, and the bucket was lowered right
was as follows : A to the bottom of the and to the under side of the upper door and sliding out The mode of working these looks down working chamber, with fixed 36 and there filled with the of the excavation, or elf e and in with it, thus bringing the point of sus- 3-ton steam crane jib (see Figs. 51), spoil but with was the chain was taken off and attached to one already pension immediately into the centre of ths shaft. provided quick-moving slewing gear, filled. A was then the bucket was strutted in all signal given, directions. A number of balks piers on Inchgarvie and the four piers at Queens- drawn into the the lower door up empty lock, were first placed all round, and, where necessary, ferry. The two former are founded on the solid closed, the air let out of the the driven into compressed lock, down the soil as far as required. rock, sloping here at an angle of about one in five upper door drawn back, the chain taken iron or belts were laid round all these. to the winding Strong hoops south-west ; while the four piers at Queens- off, and crane chain the bucket drawn and then the between these attached, filling guide timbers ferry are placed on the boulder clay which is found and on a shoot over the side of the up discharged carried on, all of them being V grooved on the one there in a very hard and solid state at a minimum and the same as before caisson, process repeated side, and the other side V shaped to fit the groove. depth of 48 ft. below high water. The boulder described. In the shown it drawing (Fig. 41) Finally, wedge piles or closing piles were driven clay here is sloping to north-north-east, also about will be noticed that the bucket in its ascent in in between the other balks, and as many as could one in five. These caissons were all sunk by means the lock touched a and indication of its be at were bolted to lever, gave got tight up the skin of the of the pneumatic process at considerable depth a whistle as whereabouts steam ; but, an addi- caisson where it was sound. ten months by Nearly had under water, under some difficulty, and under tional small wheel was in since the accident occurred before precaution, gear placed elapsed the tim- great pressure of air. To manipulate these cylinders connection with the ber barrel was in such a condition that winding drum-shaft, and, by pumping of immense size, weight, and height, in the face of means of a dial and indicated the out could pointer, position be proceeded with (see Fig. 40). The the uncertain conditions of wind and weather, and of the bucket at all points of its course. ground under the side was now under the influence of a tidal high dredged away, strong current ; to The lever acted the rod which K upon long L, and both air and water were forced down the air- put them weighing between 3000 and 4000 was so thatone of its ends was within shafts into to or arranged always the chamber wash force out as much tons into their places, and to hold them there a hole drilled in the frames of the and as from underneath. sliding doors, possible Pumping was then and pass them down through material ranging that either one door or the other was made all leaks as thereby commenced, they showed being dealt from soft mud to hard rock, was certainly a immovable. with absolutely in any suitable manner, further stiffening most formidable task. Yet, with one excep- The two valves water to the rams inside resorted to where and admitting necessary, thus, step tion, just above mentioned, namely, the tilting the doors are seen at D D close the lost working sliding by step, ground fought for. Weight was of the Queensferry north-west caisson, these huge each carried a out of which added on the side together; handwheel, also high by commencing to cylinders caused proportionately less trouble and a is and into this the rim of the segment cut, build a brick casing against the outer shell. anxiety than the shallow cofferdams of the other other Awheel fitted. In the here shown this work was position Patiently persevered with, and at foundations. This was, no doubt, owing in a great the valve is and its handwheel cannot upper closed, last, one Sunday morning, October 19, 1885, some- measure to the practical knowledge and expe- be turned unless the handwheel of the lower is turned round to bring the cut-out segment exactly opposite. In that position, however, the lower valve would be closed, and it is, therefore, easy to perceive that, so long as the handwheels remained attached to the valves, it was impossible to open both simultaneously. Since no workmen passed through these locks, it was not necessary to admit or discharge the air the inlet and outlet pressure by degrees ; cocks were, therefore, large, and acted expeditiously to reduce the loss of time.
ACCIDENT TO No. 4, OR QUEENSFERRY NORTH- WEST CAISSON. This caisson was built and launched in the usual way and towed into position at the north-west corner of the Queensferry jetty in December, 1885. It was secured to the staging in the usual-, way, allowing it to rise and fall with the tide pending the .putting on and rivetting of the remaining courses of plates at top, and the otherwise com- pleting it for the sinking process. Owing to the inconsiderable depth of water, the cutting edge touched the mud soon after half ebb, and embedded itself at low water. On New Year's Day, 1884, an exceptionally high tide occurred, folk weJ by an equally exceptional low ebb, and the caision sank deeply into the mud, assuming, no doubt, some- what of a list or dip in accordance with the natural alope of the mud. The cutting edge entered so deeply into the more solid portion of the mud or silt that, on the flood tide returning, the water could not get underneath, and the caisson failed to rise with the tide. Not being built high enough, the water soon flowed filled it in, and completely ; and on ebbing, as the lower sluice valves could not be got at, the caisson became top-heavy, and tilted still more over towards the low side. At last, it began to slide in the same direction, and moved thus for about 20 ft., when it stopped. In this FIG. 46. TILTED CAISSON AT SOUTH QUEENSFERRT. position the lowest portion of the top plates re- mained fully 6 ft. under low water, and it became of this of necessary to arrange to add to its height before what unexpectedly, the caisson raised itself cut of rience of the men in charge portion pumping could be resorted to. A number of divers its muddy bed and floated once more. It was at the work. The sinking of these six caissons time was lost in was let as a sub-contract to M. of were employed to bolt on two or three tiers of once drawn into position, and no Coiseau, As it was im- Paris and whose staff of men plates. commencing the sinking process. Antwerp, large the where it had been for several in the con- Arrangements were made to stiffen the caisson possible to place a new shell in place engaged years leave this and not structiontion of the and harbour walls internally by timber struts on top, and to keep on was rent, it was decided to alone, great quays of the inner shell and docks atat, the latterlatte the stiffening in the same manner as the pumps suc- to proceed with the building either, place by pneumatic be as well to take this ceeded in reducing the water level inside the but to substitute for both a stout lining of clinker process. It would oppor- its the notion which has somehow caisson. Unfortunately, the pumping was carried bricks built in cement. The shape of this and tunity of dispelling that the workmen on at too great a rate for the carpenters who were strength are shown in Fig. 47. gained credence, foreign mostly and the two south North with a of to put in the strutting, and the thin plating could The three other Queensferry Italians, sprinkling French, been sunk and Germans were better not support the pressure of the water from Inchgarvie caissons had in the mean time Belgians, Austrians, fact had dis- able to work in and resist the outside. The plates gave way, and a great rent, to their full depth, and in nearly high atmospheric all and to this kind of than the right across the lower side of the caisson, some appeared out of sight, and machinery pressures necessary work, with this the British workmen. That this is not so is 25 ft. to 30 ft. long, was the result. After dis- apparatus were available for dealing proved by the that of the Forth cussing many plans suggested for getting out of last. fact large numbers Bridge this and labourers this dilHculty, it was resolved to construct a sheath Before the middle of February, 1886, men carpenters, fitters, ordinary his brethren far were and of or barrel of 12-in. timber balks all round the prodigal among caissons had joined frequently employed below, many there is no reason their for the first when the (aiss)ii, to bolt as many of these balks as could down in the prehistoric clay, and number time, pressure on it without be got at firmly through the iron skin, and to make to think that the masonary pile which stands was already considerable, experiencing ;;ny or harm. It in the first the bast joint that could be got either by puddle is less able to carry its duo share of the enormous great inconvenience is, clay or cement grouting, or a combination of both. load laid on them than either of the others. instance, a matter of habit, although it certainly on from < All this work below had to be done by divers, and The foundations of the four circular piers requires good health, freedom pulmonary Inch- there ore required a considerable time in doing. Fife, and of the two circular north piers on gastric weakness, and abstemiousness, or, any rate, In the first a circular timber frame have been dealt with, and it remains moderation in taking strong spirituous liquors, instance, heavy garvie, fully | most hands of M. was placed inside the caisson near the top and to describe the mode of founding the two south Some of the experienced cr CA'..SFORNIA DEPARTMENT OF CIV1U ENGINEERING BERKEUEY. CALIFORNIA
been too Various researches Coiseau suffered when they had making wore made by members of the lost here from this cause, which in other works had free with the whisky overnight, and a good dual medical staff in the endeavour to give relief or proved fatal to so many. of disorders that ensued were traceable to the obtain a so not with of the cure, but, far, any degree In using the ejectors the following mode of same source on the other hand, wet feet, iccess. ; though, working was employed. (See Fig. 48.) A sort or incautious and sudden change from a heated of sump or hollow in the was SINKING OF THE CAISSONS. ground formed, atmosphere into a cold and biting east wind, in- and into this the water from an overhead tank of and want of nourish- The of a caisson sufficiency clothing, proper operation sinking through mud, was allowed to flow in any quantity desired, ment, had their influence in causing illness among silt, or clay differs somewhat from that pursued in and mixed with the more solid material exca- the workers. Although these six caissons were sinking through solid rock, at any rate in the mode vated. A man who held the end of the flexible hose ft. 89 ft. of founded at depths varying from C3 to attack. attached to the ejector manipulated the same in such below high water, with an average time of seventy- In the Queensferry caissons the first thing to be a manner that a certain amount of the air inside the not one death can be done was to fix in the one for the eight days for each, properly pipes air-shaft, chamber was allowed to enter into the ejector pipe in admission of the other for the removal of and justly attributed to working high pressure. water, with the mixture in the sump. This air in escaping the but both were mud diluted with water. As this of Two men died during time, process ejecting carried with it a certain amount of liquid, and forced already consumptive when they commenced working matter will be described further on, it need only be it out at one of the openings in the caissons above here, and the rigour of a Scotch winter had, at any mentioned that by degrees the shaft first, and next a water level. The operation is shown in the cut air underneath it in rate, as much to do with their death as the space the air-chamber, was cleared, figured here. It is somewhat puzzling at first and had to and access had to the latter. soon as pressure. Another man became insane, As the to understand why the air pressure, which is only be sent back to his own country. ejector pipes described above could be reached, or that which is j just equal, only slightly exceeding effect the air flexible hose was attached to and a The principal bad produced by pros- ! them, larger due to the head of water outside, should lift and
Fig 40.
Fio. 47. SECTION OF TILTED CAISSON AFTER COMPLETION.
FIG. 48. SINKING THE QUEEXSFERRY CAISSONS. HYDRAULIC SPADE.
8 sure appears to be that of severe pains in the joint number of men employed to clear the caisson discharge a quantity of semi-solid material at a level and muscles of the arms and legs. As these have of the semi-fluid mud. Great care was required above the water; the explanation will, however, lie been, in most cases, traced to hard work and con- during this early stage of the work, and the weight found in the fact that the velocity of the air due to sequent copious perspiration, and also to too long a of the caisson regulated to a nicety, for there was this pressure is very much higher than that of water stay under pressure, it has been suggested as a pro- nothing but its buoyancy to prevent it from suddenly flowing under the same head, and that it carried bable cause that small globules of air make their way descending and smothering the men below. At low mechanically along with it as much of the fluid as it through the skin, or between the skins, where they water was naturally the most dangerous time, there could convey. Of course the man who manipulated remain, and on the workman returning to ordinary being the least displacement in action then, while the end of the hose in the sump had to feel his way atmospheric pressure, expand, and thereby cause the the weight was greatest, and moreover the cutting into the solution of this problem, and had to vary the most agonising pains in the joints, elbows, edge resting upon a treacherous ground. The men the quantities or proportions of air and liquid shoulders, knee-caps, and other places. In seeming were generally withdrawn at this time, and the air according to the requirements of the moment. confirmation of this, the sufferers got instant relief pressure diminished, allowing the caisson to descend Outside the caisson the flow from this ejector was on returning into the high pressure. Thus it as far as it would go. On one of these occasions not continuous, but in gulps, like that from a single of those afflicted with this the caisson happened that many suddenly descended some 7 ft., and not plunger pump, now in a large mass, now in a thin disorder spent the greater part of Saturday after- only the air-chamber but part of the ascending shaft stream, and at times nothing at all. noon and Sunday under air pressure, and only became filled again with mud and silt. It is satis- As soon as all the soft material had been re- came out when absolutely obliged to do so. factory to be able to say that not a single life was moved, and a bed of stift'er clay reached, the ejector could be used for the only removing superfluous proper position. The slight upward taper in the ill the direction in which it is intended that it should and and had to be resorted water, picks heavy spades cylindrical portion of the caisson added some little go. This should also be done at high tide, when the to and the' material into the buckets and in that and writer thinks that charged help direction, the a buoyancy of the caisson is largest. As in all things, hoisted out the locks. Lines of rail- by narrow-gauge little more taper than that given to the Forth so here, prevention is better than cure, and it is were laid down to run small on which way bogies, Bridge caissons would be found very advantageous best to keep a sharp eye upon the workmen in the the were carried in all directions within the skips in future works of this kind. Another plan is to chamber, to insist that the edge be undercut on the the chamber. Presently hard boulder clay was set up inside the air-chamber and against the top of outside to the extent of 6 in. to 8 in. all round reached, which was dry, and which the of the a number of nearly proved sloping plates shoe, strong before it is allowed to descend, and to have the posi- tougher and harder than anything the existing tools could work in. Various means were tried, and even blasting by powder or dynamite resorted to, but with little result. The rate of progress became exceedingly slow, and the men's energies became quite exhausted. Here Mr. Arrol's inge- Cra nuity fortunately came to the rescue, and he devised a most simple, yet a most efficient, tool to "K&Z grapple with this difficulty namely, a hydraulic spade shown in Figs. 49 and 50. It consisted in the main of a ram, to which a spade is attached, the ram fitting into a cylinder, which represents the handle of the spade. On the top of the cylinder was fitted a head-piece, which could be set against a piece of batten or any other convenient object. The ceiling of the air-chamber furnished the resist- ance, and the projecting rivet heads were useful in preventing side slip of the head-piece. The spade was lifted by two men, a third attending to the fixing of the head and the turning of the cock admitting water pressure. This was of the ordinary amount, namely, 1000 Ib. per square inch, less the amount of air pressure inside the caisson. The spade was set on the ground, the pressure turned on, and as soon as the head-piece had been firmly set against the ceiling the full pressure was given, and the spade forced down into the clay. The water was then exhausted and the spade brought forward, thereby detaching a slab of clay from 16 in. to 18 in. dee]), and from 2 in. to 4 in. thick. The spade was then set up again, and the clay thus cut away in long ridges all over the area. Many of these slabs of clay had to be cut to allow them to be charged into the skips. Any boulders too large to pass through the air-shaft were either drilled and blasted, or left in the chamber to be hereafter incorporated with the concrete filling. The water discharged by the spades had to be collected in a sump and discharged through an ejector. In digging or undercutting the edge of the cais- son all round, the spades had to be worked at an angle varying from 30 deg. to 60 deg., the rivet- heads coming in usefully hero to provide a good hold for the headpiece of the spade. In undercutting round the sides, portions were left standing to carry the weight of the caisson while excavation was still going on, and these por- tions were by degrees rtmoved until the bearing surface became too small to sustain the weight, and the caisson settled down into them. In proportion as the caisson descended, more weight was added on the but this also to be top ; was required done with care, for fear of displacements taking place. After entering into the hard clay, the caisson edge was sealed the of the water nearly by pressure Fir:. 51. SECTION OF CAISSONS WITH AIR-LOCKS AND WORKING CHAMBER. upon the clay outside, and instead of the pressure of air to the head of water a corresponding outside, TABLE No. V. PROGRESS OF WORK WITH QUEENSFERRY CAISSONS AND PIERS. few pounds sufficed to keep the caisson dry. Tims, in the case of the Queensferry north-east caisson, founded at 89 ft. below high water, the out- side head is equal to fully 42 Ib. of air pressure inside, but it was actually worked and finished with a pressure of from 15 Ib. to 18 Ib. per square inch, after once the hard clay had been entered. This made it, of course, much easier for the men to work in, apart from a considerable saving of wear and tear of the machinery. It will be readily understood that it was of para- mount importance that the caissons, when sunk to their final depth, should be in the correct positions laid down for them it is ; yet equally easy to under- stand that in sinking such a mass it would not take a great deal to cause a displacement in one way or other, since there is nothing to hold it in its proper centre. The position of each cai son was therefore checked nearly every day, and if it deviated in any way from its right course, steps were at once taken to remedy this. To do this it was only necessary to undercut the caisson edge on the side to which it had moved, and to gradually tilt it to a small degree in the direction of that side. When this had been done the caisson was sunk further down for a distance with this tilt on it, and was then righted by undercutting on the high side. This was repeated until the centre of the caisson had got back to its * oo 00 r f"lj|
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' (PJfle '" - silt mud and had been removed previous to its I launching the two Inchgarvie caissons, a strong pressors Were worked at somewhat greater speed 1 raised hence the at timber shoe was fixed in of the to increase the the chamber was soon icing ; greater depth commence- each two places pressure, and merit of sinking. which would come to lie immediately upon the two clear again. The firing was done as often as When working in the hard boulder clay, for piers (Figs. 30 and 31), built up of concrete bags on possible at the end of a shift to cause the least twenty-four hours with the full complement of the opposite side to where the caisson was likely delay and loss of time. The firing of the blocks of twenty-seven men below in the air-chamber, and to first touch the rock. The timber frame was rock upon which the caisson rested, was generally with four hydraulic spades going, a bucket was sent brought down flush with the cutting edge, so as to done at low water, the caisson crushing into the up every five minutes, or 288 buckets in the twenty- five the caisson a solid base to rest on. debris with irresistible force. A number of men j then descended and cleared away the debris, which TABLE No. VI. NATURE AND DEPTH OF STRATA THROUGH WHICH CAISSONS WERE SUNK. was sent up in the skips, passed through the lock, and discharged over the side as described in ' vel of mud or silt 27ft. , _ . _ . . , . ,. All below P^ case ot the yueensrerry piers. Another lot ot ,, clay and boulder clay 48ft. 52i ft ' 75ft.75 ft 02 ftft. men cleared away some of the sandbags and cut ,, cutting edge at finish 71 *t. 73 ft 89 ft.ft 8585ft.ft Water. | under the into the concrete while the h. ft. edge piers, l^Depth^ through hard ground .. 23 20| 14 ft. 23ft. remainder, were at once set to to drill fresh holes Total excavation in cubic yards C372 C(i51 6827 6271 where isolated points remained standing. four hours, which was equal to a little over 5 cubic ' When floated across from the Queensferry jetty As mentioned in connection with the Queens- yards per man per twelve-hour shift. The total the caissons were at once attached to the mooring ferry caissons, careful examination was daily made, amount of excavation over the full area was equal chains provided for them, and, in addition, had or even oftener, as to the position of the centre of the to 145 cubic yards for each foot in depth. Even this stout wire ropes passed round them, the other ends caisson, and if it had shifted it was at once tilted rate of progress was frequently exceeded under of which were passed round the north piers already i to one side and speedily brought back to its place. favourable circumstances, but was of course largely ' s v v. v v s s SS"^i above the average daily work. Granite 1'ier c ro /ea^' The different strata through which the caissons passed, were water, deposited mud, stiff mud, silt, a layer of pebbles and stones, soft clay and boulder clay. In the last strata were found large rocks well rounded off, of granite, limestone, free- stone and other kinds, many of which showed upon their flat faces, the distinct grooving or scoring due to glacier action. Amethysts and pebbles of all sorts, and large round boulders of conglomerate were also found, but no traces of fossils or of animal life, not even a live toad. The excavation finished, the chamber was cleared of all material used during sinking, and preparations made for filling the whole space with concrete. The bottom ends of the air-shafts were closed by plates \\ \ previously prepared, to which was attached a STRUTS AND WEDGES IN AIR-CHAMBER hinged door opening downwards. The large air built. Careful watch was kept day and night to guard locks were then removed from the tops of the shafts, accidents, and further with concrete and small tubes 18 in. in diameter fixed inside and against loading was at once with, while the carried up some distance to a platform, where the proceeded remaining &c. were and concrete mixer was stationed. A valve or small air- air-locks, , placed inside, tubes for the of air lock was set on the top of the 18 in. tube. Outside supply compressed and water, attached. As soon as the caisson com- the latter was of course ordinary atmospheric menced to touch ground at low water, the pressure. Similar arrangements were made for was sus ended and a into air"- P . descent made the the other small shafts placed in the caissons from to examine the points where the cutting the beginning. Concrete was now deposited close Camber edg s touching and to put in any further to the lock, a signal was given, and the lower i su ort that be considered advisable.
, PP might door in the air-chamber was hermetically sealed, the this wa two of were built to the i wayy ^ sandbags up air let out of the shaft and the upper valve opened, **. P ceiling as an additional safeguard against slipping, Concrete was shovelled in till the pipe was nearly and these piers were near the centre of the caisson, filled, the door then closed, and a signal given. but rather on the side of the concrete Work Those below then opened a small valve to let com- piers. was now commenced in short shifts, both before pressed air into the shaft, the lower hinged door was and after low water, in order to remove as much opened and the mass of concrete fell on the floor rock as under the on the and was taken up into barrows and carried all round possible cutting edge high side, as it was deemed advisable that at least one- the edge. There it was firmly rammed in and fourth to one-fifth of the circumference should rest pounded with wooden rammers into every hole and on the solid rock and in a sort of chase before the corner, and thun gradually laid up the sloping face was loaded to such an extent as to I prevent of the shoe. Against the ceiling also the concrete caisson. >ts even at water. It was thus was and thus the whole floating high fully carefully rammed, by degrees j a fortnight after the caisson was moored m its chamber built in, leaving only passages between the lace before jt was allowed to settle down, and to places where the concrete way passed down. These P. nse no ore - Excavation then commenced m also were by degrees tilled up and the last of the . earnest, the rate of was slow at concrete had to be passed through the men's lock and although progress firs* ow to tlle small area which down the air-shaft in , mg comparatively buckets until this also had to be , , could en bc attacked. The mode of was filled. The air pressure was of course kept on during working A number of holes were drilled at all this time to the water from in and very simple. keep washing '''* ordinary hand one man holding the -? ; out. Finally, all the shafts were filled up, and cement ^ jumpers, v" ?; '^'^'.f.'-i! 'j~ has been described. Previous to time. After the fired the air com- ; sandbags, already charges were The rock-drills were of an ordinary type, mounted On three-legged stools ov stands for vertical or good working order, they drilled a largo iiuuiber of steep-inclined drilling, and on timber frames for holes in the course of a day. horizontal or slightly-inclined working. The ar- In these two caissons the tendency to go down rangemcnt through which they were made to dis- hill manifested itself strongly, and powerful timber fy.54. | rp/7nec/;rty angles MODE OP FIXING UNDER BEDPLATES ON PIERS. TABLE No. VII. PROGRESS OF WORK ON INCHGARVIE CAISSONS. TABLE No. VIII. CIRCULAR GRANITE PIERS. TABULAR STATEMENT OF QUANTITIES. ALL EXCAVATION CONCRETE, RUBBLE, AND BRICKWORK IN CUBIC YARDS. GRANITE IN CUBIC FEET. STEEL, IKON, AND CAST IRON TONS, CWTS. AND QRH. TABLE No. IX. VIADUCT PIEKS AND CANTILEVER END PIELS. TABULAR STATEMENT OF QUANTITIES. in All Figures for Comrete, and Rubble in Cubic. Yards for Grnnilr. Cubic Feet. ' a that the could I removed from under and was transferred All materials for building were raised to the girder clusively, as it was feared cojicrete it, spall of hoists stationed at either not set hard in the time allowed between further forward. level by means two end, | sufficiently rubble set After the were in the and the materials so raised were run on trollies by the lifts, while the Arbroath masonry \ piers position temporary connections at the where had been boys or drawn by Shetland ponies to the places firmly and solidly in about thirty hours. joints provision 0, G3 Fig. HALF SECTION CROSS StCTlON BENDING PRESS FOR PLATES AND MACHINE FOR PLANING ENDS OF CURVED PLATES. where thay wore required. Thuj granite blocks, Arbroath rubble, and mortar, were all prepared on the jetty bslow and lifted up. To assist the masons in their work of laying granite and rubble an overhead traveller was placed to each side of every pier. All these 'travellers were worked by friction gear and clutches, both for hoisting and lowering, or for travelling, an endless wire rope being run along the girders from end to end, driven by the same engines which drove the pumps during lifting. When the seven spans had thus been raised to 47 ft. above high water, the next two spans from pier 3 to pier 1 which in the meantime had been erected on staging passing over the Edinburgh-road were joined on, and the further lifting proceeded with in the same manner as before. The last span from abutment to pier 1 had meanwhile been erected on staging at level 119 ft. above high water, and was joined on when the other girders reached that level, the complete viaduct being then raised through the remaining 11 ft. The first lift at South Queensferry was made from level 23 ft. above high water in May, 1886. Level 47 ft. above high water was reached August 10, 1886. Level 91 ft. above high water was reached Feb- ruary 15, 1887. Level 119 ft. above high water was reached June 14, 1887. Level 130 ft. 6 in. or top was reached August 7, 1887. No mishap of any kind occurred in the course of this work, and in no case did the granite facing or rubble backing show the least sign of giving way during the underbuilding of the piers under this considerable load. After the girders had reached the tops of the piers the cross and rams were removed girders hydraulic Fi5. 66. MACHINE FOR PLANING EDGES OF CURVED PLATES. and the bedplate; substituted. In all cases the thirteen viaduct piers had the Very little staging was used in this mode of erect- made for expansion and contraction were removed, hearting constructed of concrete uj> to the level at ing, most of the timber being used over and over and the remaining buckle-plates on the top and the which the girders were built, but from the time again, for as soon as a girder was rivetted up and wind-fence on both sides were put on. lifting was done Arbroath rubble was used e could carry itself across the span the staging was After several coats of paint had bsen put on the were left until the time when the of much anxious girders they per- ject thought and reflection to the result being one single corkscrew shaving, about manent was to be laid down. One in whatever the way required engineers. But, way decision was one yard in length, started from the very moment the of the views on Plate VIII. shows the arrived there can be no two drill girders at, opinions that the touched the steel and attached yet by the end at full choice was a one. height. happy From beginning and to the piece of scrap out of which it was bored. It THE STEEL. a time before the probably long beginning of this would not, probably, be straining a fact to assume With the of a tons of to exception few hundred work the end, this steel was subjected to every that this behaviour of the steel under severe tests cast-iron washers and anchor-plat ei in the piers, conceivable test, both in a properly scientific had a great deal to do with the confidence with which the workmen regarded every portion of the structure, and with their belief that no possible load DRILL ROADS they could pile on the temporary platforms could by any chance bring about a collapse. It is true that, in the early days of plate-bending, some thick plates broke near the edges in a seemingly mys- terious manner, but the investigations made and the reasons adduced in connection with these frac- tures were sufficiently convincing to allay any feeling of distrust. The Board of Trade stipulations in regard to steel for structures, do not go further than to lay down the rule that the maximum working stress should not exceed one-fourth of the ultimate breaking strain of the steel. No difference is made between the tensile and compressive stresses, nor is any re- gard paid to the differences between stresses due to dead load or live load alone or in combination nor to the circumstances arising from changes, occurring frequently or rarely, in the nature of the stresses. The therefore laid after consul- FIG. 67. PLAN OF DRILL ROADS. engineers down, BOTTOM MEMBER ON DRILL ROAD. and about 2000 tons of deadweight consisting of manner for purposes of research or investigation, tation with the Board of Trade and with their cast-iron bricks laid in asphalt which are placed and in an entirely unscientific manner by workmen, certain rules in regard to the stresses in the ends of the two fixed cantilevers terminating whose only excuse can be that they did not know admissible under Varying circumstances. in cantilever the end piers the whole superstruc- better. But in all cases the steel stood the test, For tension members the steel was to have an from ture, holding-down bolts to the ventilators on and a more uniform, a more homogeneous, and ultimate resistance of not less than 30 nor more than the extreme of the vertical top columns, and from more satisfactory material could not be wished for. 33 tons per square inch, with an elongation in 8 in. the arches at one granite end to those at the other To only quote one instance, the writer has in his of at least 20 per cent. For compression members is built of steel. end, possession several pieces of scrap from the shearing- a resistance not less than 34 tons nor more than The choice of a material for a constructing bridge machine, picked up promiscuously and placed under 37 tons per square inch, with 17 per cent, elongation. of novel of design, extraordinary magnitude, and an ordinary diamond-headed drill about 1 in. in With regard to varying stresses for a load varying erection to the effects of exposed during powerful diameter. A hole was drilled about f in deep, and between nil and a maximum, 20 tons per squai e atmospheric disturbances, must have been the sub- the machine stopped while yet the feed was on, the inch of section to be assumed as the ultimate TUBE DRILLING MACHINE ON DRILL ROAD. Fig. 72, strength if the change occurs frequently, and 22| tons if occurring rarely. For stresses alternately tensile and compressive, the ultimate stress to be 10 tons if frequent and 15 tons if seldom, one-third of the ultimate strength to be considered the working stress. Rivet-steel to have an ultimate strength of 27 tons per square inch, with 30 per cent, of elongation, and shearing resistance to be from 22 tons to 24 tons per square inch. Cast steel to have an ultimate tensile strength of 30 tons, with 8 to 10 per cent, elongation. For tension members the sectional area of the rivets in the joints to be 1 times the useful section of the boom. For compression members the area of rivets in butt-joints to be half the useful section of the member. The original estimate gave the quantity of steel required for the Cantilever Bridge (not including approach viaduct spans) as 42,000 tons. Of this quantity the Landore Works near .Swansea in South Wales, of Messrs. Siemens, supplied 12,000 tons, and the Steel Company of Scotland, from their Blochairn and Newton Works near the of in. thickness with the ends of the Glasgow, H test-piece engineers previous to being passed into the work- 30,000 tons. For the alterations made closed. As the steel the remaining regards supplied by Steel shops. If necessary, full-size drawings were made subsequently in the design, and the increase of of Scotland, all were rolled at the on the blackened floor of Company plates the large drawing loft, section in various a further of about Blochairn and all at parts, quantity Works, bars the Newton Works. and from these all templates were made in wood. 16,000 tons was required, about one-half of which Failures of the steel under test were of the The templates were carefully cut to size, all holes, was the Stoel of rarest occurrence. supplied by Company Scotland, drilled in them, and all necessary information and the other half Dal/ell's Iron and Steel All steel was by manufactured by the Siemens- and description branded upon the template in clear Works at near The steel Martin and all Motherwell, Glasgow. open-hearth process, plates, bars, type. In certain cases, such as bracing bars, which for the viaduct about 3200 is not spans, tons, tees, angles, and other pieces, were cut to length and recur several hundred times over, some of the bars included in the above. The as ordered and thus delivered at 1 figures given Clyde shape the works. themselves were used as templates. For the erec. FlCi. 75. TfliE DRILLING MACHINE AND TRAVELLING fKANE ON DRILL ROAD. Fir.. 76. PLAN OF No. 1 DRILL SHED. about 4200 tons Rivet Company, Glasgow, supplied About C per cent, of the total steel delivered was tion of the superstructure the tracings were trans- of rivets. returned as scrap, or between 3000 tons and 4000 ferred to sheets prepared by the ferro-prussiate to one out of With regard tests, plate every fifty, tons. A certain proportion of the steel delivered process, by which the only part of the paper out a cut out picked promiscuously, had strip of was used for temporary purposes only, and this will remaining white is that which underlies the full or it which was on all four sides and tested for account for the planed difference between the total quantity dotted lines of the tracings. The drawing is, stress in a 50-ton machine. tensile testing The delivered and that erected. therefore, of white lines upon a deep blue ground. same proportion was observed in the case of bars. For transverse or bending tests a piece was cut DRAWING?. WORKSHOPS. and about 2 in. off every plate every bar, wide, All detail drawings were made at the drawing Two principal divisions were made in regard to and tested by being bent under the press to a radius offices attached to the works and submitted to the the construction, namely, between the tubular members and the latticed girders. The former Fig. 74.) The beams were now bolted with their spindles were thereby placed at rigat angles were done in the upper or No. 2 shed and on the inner ends to the angle-iron rings of the dia- instead of radially. the the Besides drill-roads it the in the lower or ; and on beams inside, and the machines here described there were adjoining ; latter, phragms again, No. 1 shed. Considering that as much of the work later the outside, plates were fixed by means of a number of others, all for special purposes, each all and draw-washers. The under- of which carried out its work in a most as could possibly be done was to be drilled with ordinary clamps by appointed understood side of the tube was also timber efficient manner. different of parts put together, it will be at once supported by Many types hydraulic built from the centre of the for the that not only did the drilling form a most important blocks ground. The presses shaping of bars or corner plates for of mandrel was now checked means of a the struts were and had con- part of the wor):, but also that a great deal by theodolite, square-ended used, if corrected. All was now to be altered as circumstances special plant designed for each particular purpose and, necessary, ready stantly required. that all holes in the similar in would be required. As a broad rule, therefore, all for drilling, except, perhaps, Drilling machines, only respect of the tubular members were put together and drilled lap-joints of the plates and those for the circular fact that they drilled holes, and that they moved through the various thicknesses at once, the only girders required to be marked. The drilling alongside the work which was made a fixture, were for this was now in use in the lower or No. 1 shed. parts done separately being the portions of beams machine, specially designed work, (See Fig. 76.) and It con- These at and diaphragms not in contact with the outer shell. brought forward. (Figs. 72, 73, 75.) machines had times ten boring spindles drilled sists of a on a at one and the same and there were In the lattice-girders the booms were wrought-iron carriage A running going time, of double line of rails on each side of the and on several of the machines as as thirteen singly, on specially prepared beds, made up tube, many if on cast-iron to it are fixed in the centre line of the tube two available for use. These timber blocks ; or, worth while, spindles multiple drilling 1 frames. The lattice-bars were drilled by other circular frames C about 10 ft. apart, and com- machines are shown in Figs. 77, 78, 79, and 80. machines. pletely embracing the tube with about 6 in. of Here also an ingenious tool was in operation In the building of the tubular members the first play all round. Upon the frames are placed five which cut the 3-in. round holes out of the lower work to be done was to bend the plates to the cross-girders D D, so arranged that by means of bedplates, and which also cut the larger round holes required curve. For this purpose the plates were circular rack and worm B B they can work right 7 in. in diameter, and the oblong holes 11 in. by ! the each two with rounded corners out of the put into a gas furnace (sec Figs. CO and 61), round tube, girder carrying spindles 7 in., (see Fig. 96), Fig 7S MACHINE 1 MULTIPLE DRILLING ; No. SHED. heated up to a bright red heat, and then passed H H, which can run from end to end. On one side upper bedplates. Tliismachinc consisted of a '- into a hydraulic press, where, between two dies of the carriage is placed an engine EE and boiler, spindle turned by worm and wheel, and upon this or saddles, they received the necessary curvatures. and the driving of the spindles is accomplished by spindle was a saddle in which could move forward (See Figs. 62 and 03.) The plates were then an endless cotton rope. Thus arranged, the ten and backward a horizontal slide which carried a roller placed aside in piles, covered with ashes, and spindles point radially to the centre of the tube, no on top, and a cutting tool at bottom. The roller gradually cooled down. However carefully this is matter where placed. This machine was now : at top moved between two frames, which could be done, some alteration takes place in the shape of pushed forward to the tube, timber packings being removed at will, and which had the same shape the and to this the removed in front and as the it was desired hole cut the tool plates ; remedy plates, when replaced behind which the below by quite cold, were put into the hydraulic press once machine advanced, and drilling was carried on should have. It followed therefore that whatever more and received a final setting. They were then until all holes (about 100 per foot run) in the 8 ft. shape these frames had, the tool was obliged placed into a planing machine (see Fig. 66), section were drilled. The machine was then moved to follow and cut a hole the same shape. By where the two long side edges were planed down forward to the next section. On the side to which placing the tool at different distances from the to the dimensions while in another the machine was i roller at required ; moving new beams and plates were revolving centre while leaving the the same machine of simple construction the end edges were always added, while on the other side they were distance, the size of the hole could bo diminished dealt with in the same manner. (See Figs. 64 and removed and taken to the stack-yard. Before or increased to any desired scale. A machine for 65.) They were now ready to be built up into being removed, however, every plate, every beam, planing the very long plates required in the lattice ; tubes on the drill-roads. (See Fig. 67.) Here a angle, cover or strap was typed with distinguishing girders is shown in Figs. 81, 82, and 83. It will long cylinder, or mandrel with wings attached, was letters, which made it possible, at a moment's be noticed tint it has an end saddle and tool an well, j supported on a number of trestles, and round this notice, to fix its position in the structure. In thus allowing two edges of the plate to be planed at mandrel the tube was built up, the diaphragms tubular members other than circular, the side one time. A further feature of the machine is the bolted to the of the mandrel. frames in being wings (Figs. which the cross-girders which carried the I use of hydraulic rams for holding down the plate in ' 68, 69, 70, and 71.) Meanwhile, the beams had been boring spindles moved, instead of being circular, lieu of the usual screws. prepared and drilled with the angles attached by were of the .same shape as the members them- Here all the tension members, wind-bracing radial machines in the selves and on flat for the and the with flat ordinary drilling shop. (See ; surfaces, instance, girders, bedplates, top junctions sides were put together and drilled, as also a mass (see Fig. 75), some with curved jibs 40 ft. high, were machines, and could be finished at an extremely of small detail work, and all the temporary girders used, and these could move about all over the drill- cheap rate. used in tho erection and in the stagings. roads, being shifted from one line of rails to another The work in both No. 1 and No. 2 sheds, and on the Outside these workshops and the drill-roads, many by means of traversers. Ordinary derrick cranes drill-roads, was carried on day and night, though acres of ground were taken up with the building up worked by steam or by hand were also largely the number of men was much greater during the and fitting together of the various girders, of which used. .lay-time. The working hours were from 6 a.m. till 5.15 the single booms had been drilled in No. 1 shed. In the shops, however, most of this work was p.m., and from 5.45 p.m. until 5.45 a.m. for Thus a great portion of the internal viaduct was done by hydraulic cranes of very simple construc- night shift. No deduction was made for meal hours the the put together and a number of bracings which had tion, yet eminently adapted for their work. (See during night, full twelve hours being paid to be templated in the first instance in situ, were Figs. 84 and 85.) In many places they were so dis- for. When necessary the work in the field was also carried on the done and multiplied. These portions of the internal posed that material could be lifted and swung round during night. The total output of work from all these places has amounted to as much as 1800 tons in a month, which is a very large quantity when it is considered Fig. 79. through how many hands every piece was required to pass before it could be called finished. BKDPLATES. The lower or fixed bedplates, in size about 37 ft. long by 17 ft. wide, are built up of five layers of plates, the lowest J in. in thickness, the second 1| in., and the third and fourth 1 in., alternately laid longitudinally and transversely, to obtain dis- tribution of fibre in all directions. The fifth layer consists simply of a band, 11 in. wide and i in. thick, laid round the edges of the bedplate, partly as a stiffener, partly as a means of retaining the lubricating medium between the lower and upper bedplates. Immediately under the vertical column a recess is formed by cutting out of the two upper 1-in. plates a space varying in form, but in all cases for the purpose of admitting a keyplate of similar form, a portion of which is rivetted to and forms part of the upper bedplate. The bedplate as above described was put together on a carefully-prepared bed in No. 1 shed, clamped and fastened down securely, and a traveller with several boring spindles passed over the whole of the plate, drilling all holes through the various thicknesses at once. All holes were 1^ in. in diameter, and countersunk both top and bottom. The forty-eight holes 3 in. in diameter for the holding-down bolts were drilled in the same place, but by a specially constructed tool described above, and the plate was then taken to pieces and stowed away until wanted. As soon as the granite piers were ready for the reception of the bedplates they were put together at a height of about 4 ft. above the masonry, and supported for the time being on short pieces of bolts, coupled to the foundation bolts by long nuts and in other places by pieces of cast-iron piping of equal length. The rivetting machine was then placed at one end, and the rivetting commenced. (See Figs. 86 and 87.) The machine consisted of two strong box-plate girders, earned on two side- frames moving on wheels, and kept apart vertically a sufficient distance to admit the bedplate, with a rivetting cylinder attached to the upper and another to the lower girder. The cylinders could by screw movement be moved from one end of the girders to the other, and thus commanded the whole width of the bedplate, while for forward or backward movement the side-wheels had to be pinched. The two cylinders were turned on simul- taneously by one valve. The cylinders were 12 in. in diameter, and the water pressure 1000 Ib. per square inch. The pressure upon the rivet and the plates was, therefore, about 40 tons from each cylinder. The rivets had a countersunk head at one end, and flat snaps were used on both cylin- ders. The rivets were heated in an ordinary brick furnace placed on the pier, and brought to a full yellow heat. There were 3778 rivets in each of these bedplates, which gives for the area of 654 square feet about six rivets per square foot. As soon as the machine had moved away a yard or so from the end of the plate, chippers were set to work to pare down tho projecting piece on each rivet-head on the under side of the bedplate, in irder to have this perfectly even and flush. After the men got into the way of properly using MULTIPLE these were DRILLING MACHINE ; No. 1 SHED. the rivetting machine, bedplates rivetted up in twenty-eight hours, or 135 rivets viaduct were erected for one pair only, however, and from one to the other so as to traverse the whole itruck per hour, which is very creditable work, con- in the others it was of the size of the rivets and that so much simply repeated. length and breadth the shop. (See Fig. 7fi.) sidering or of the for tho The bottom junctions, junctions between A large amount of rivetting was done in the yards shifting of the machine and supports bottom struts and ties and members, wind-bracings and the field in the case of such portions of the bedplate had to be done. in cantilevers, were laid down and finished on the girders as the booms of the tension members, and After all the rivet-heads had been chipped, the while those of its drill-roads, the top members with later on, whole portions of the rectangular wind- bedplate was lowered into place by hydraulic ties were laid of one laid in the struts and down and built in tho bracing girders, of which then the joints only rams. Two thicknesses canvas, field. in the breadth of the both required rivetting up after they were erected. ength, the other plate, For the of the other well in and over with red handling plates, beams, and Much rivetting was also done upon the longi- >eing soaked painted cement bed parts of the tubular members and the skewbacks tudinal beams and the diaphragms in the tubular ead, were interposed between the and the to and bottom junctions, paivorful travelling cranes member.). All this rivetting was done by hydraulic described above (see granite picr.i) plate * S o* i.5 S r-H *i3] S to a a i O ^G r 2 5 JS s u a S oj 2 w hrl i-H 2 4 O2 o fS 1w ^. J e CD , rt CD S 3 -^ '^ p; ^l^-a 1 1 O ^ !|l|5 CD CD frH cc ^J -^ > w SJ *J ^ "ft n t) S tf CD "S P^ oi i w o HII H o PH H flRIp Jz; i i tlfrfSi W g 1 3-S I'l o co *- CD 3 O CD & r^ rj K . e * a s'S o A PH W O p H are the as those on precisely same Inchgarvio, while centre. The central part, or oblong key-plate, is layers of plates of varying thicknesses, according to in the south-east and and in. in Queensferry south-west, 2f thickness, and enters therefore to the position. The lowest course of plates, placed longi- the Fife north-east and north-west, both longitu- extent of f in. into the upper bedplate, to which tudinally, is f in. in thickness, and in this is cut j dinal and is 1 lateral movements are provided for. The it rivetted. This, however, is somewhat different the recess which receives the key-plate of what- former is for expansion and contraction between in the three fixed piers, for here both the two ever shape it may be. The next course is laid j the tixed circular piers and the cantilever end piers, segments and the rectangular centre-plate are all transversely 1 in. in thickness and extends, like the latter for any lateral deflection in the same alike 2j in. in thickness, and the whole key-plate, the first, over the whole area. The third course, length due to wind-pressure acting at right angles, 12 ft. in diameter, enters into the upper key-plate. laid longitudinally, again is j in. in thickness, but or nearly so. In the cantilever end piers lateral The central piece is the only one attached by rivet- extends only for about two-thirds of the area on the side next to the horizontal connecting bottom member. This plate also takes the attachments for the bottom booms of the horizontal cross bracing and the horizontal diagonal bracing. (See Fig. 91.) 85 Fig. A further thickness of plates, as a fourth course, occurs in the case of the fixed piers, to make up for the enlarged recess in these, and this course is formed under the base of the vertical columns only. These plates are stiffened by twelve girders of I section about 11 in. deep, and running longi- tudinally consisting of web-plates and four angles. The third and fifth girders on each side are omitted, the main webplates of the skewback taking their places. (See Fig. 90 ) Transversely these girders are combined and stiffened by cell-plates, flanged on all four sides in a die. There are eleven rows of these, and upon them are set the main dia- phragms, which reach from the bedplates to the crown of the skewbacks. The remaining spaces on each side of the inner webplates, and between these and the outer web-plates, are filled by similar dia- phragms, and at the same distances apart. The sections and plans shown in Figs. 89 to 94 will fully explain these parts, which are of the utmost importance, because through them all the stresses thrown upon or against the structure, must pass on to the supports. The lower half of the skewback is square in form, the upper half for about two- thirds is rounded, the remainder being squared in order to receive the attachments of the top booms of bracing girders mentioned above. The inner main webs are J in. thick on Fife and Queensferry and 1 in. HYDRAULIC CRANES. thick on Inchgarvie. and these are carried through RIVBTTING MACHINE OX PIERS FOR BEDPLATES. from end to end of the skewback at a distance of Fig.M. 3 ft. 6 in. to each side of the centre line. These plates form the main points of attachment for the S.W. N.W. S.W. N.w. 5.1V. N.W. diagonal struts and for the bottom members, both within the central in the cantilevers. Queensfetry Pier Inch Garvie Pier Fife Pier towers and The outer webplates, 1 in. thick on Fife and Queensferry and 1J in. thick on Inchgarvie, O O receive the main thrust of the vertical columns, 5836 S. f N.i SI N.t S. E N.t and are carried on each side into the bottom members a from the into ARRANGEMENT OF BF.DPLATES ON GR4NITE PIERS. by change rectangular the circular form. (See Figs. 92 and 93.) They are considerably stiffened in these parts by horizontal is but movement prevented, longitudinal movement ting, the wings simply are laid loose into the diaphragms and by doubling plates of great provided for. recesses. strength, and the skeleton work to which they are It will be noticed that the key-plates, with the The square key-plates in the bedplates of the attached is gradually merged into the main beams exception of those belonging to the fixed cantilevers, fixed cantilevers are fixed to the upper bedplate, of the regular section of the bottom members. are shown in three parts, an oblong centre-piece and enter the lower bedplate to the extent of 1 in. The attachments of the five lattice wind-bracim* of and two segments a circle. Of these, the two only, the whole bedplate being much lighter than girders, although most ingeniously contrived, does 2 in segments are only in. thickness, and therefore in the case of the free cantilevers. not call for any special remark. simply fill up the recess in the lower bedplate, The upper bedplates form the under part or foot It will be noticed in connection with the skew- while yet, however, they admit and facilitate, as of the main junctions or skewbacks. These plates backs that the centre of the vertical columns dots a round the well as control, circular movement are, like the lower bedplates, built up of several not coincide with the centre of the circular tjranitc J * aj f 1 i o> a? B 6 1 b 1 S5 S 1B a> ^, +-1 1 tr ^ a) Ss a> eC CQ P4 OB -Ti O ? S &- O is 3 3 O) i> ^ sc -jf S "3, w ^ , 2.2 e-* 1 Ilia -^ ? H O Q) 5 ^ a ^3 c/3 T3 -" ce S *-! ^ i- S S - a o -- S " ^ s " * 8 8 s "S 0"S 2^ 2 forced all round and after these were found to ram attached, 4 in. in diameter, which was bearing ; Ib. of the ! into a with 1000 Le satisfactory, the rectangular portion key- cylinder already charged water. 4-in. ram forced the water to rivetted to the bed- ; The plate was raised up and upper pressure into its a small loaded to a down ] accumulator, pressure plate. This was then lowered place produce all of the of 3 tons inch. It needs no that to see how it fitted, and whether parts per square Maying this was a tedious kind of and took a key were in proper contact. After thus lowering work, long of about 57 time to On not more than and raising it several times (a weight accomplish. many days cleaned and half a dozen rivets were done at no time more tons), the surfaces were carefully j than about a hundred in the twelve hours, and the thick brown oil of a special character was poured would not amount to more than into the key recess and on the whole area of the average probably lowered lower bedplate, and the upper bedplate twenty-five per day. but Meanwhile had been erected between the down upon it for the last time. Nothing else staging the on trestles of certain which were between ; oil was placed as lubricating medium piers height, upon tubes the two surfaces. put together the horizontal connecting The movements described in connection with the skewbacks and the cross-girders and diagonal girders. to the and of be I All these were now connected skewbacks, keyplates require that a certain amount play made to rivet them All the erec- given in the holes of the upper bedplates through preparations up. ' which the holding-down bolts pass. The amount the same manner as of play varied, of course, in with the key-plates. held down The lower bedplates being fixed and that the nuts firmly by the bolts, it was necessary should be screwed down upon them. These nuts, with shown in Fig. 95, were therefore arranged with an en- a long neck, circular in form, and holes in the larged head of hexagon form. The of such upper bedplate had to be therefore made screwed down si/.e and shape that with the nuts with a consider- I tightly upon the lower bedplates, able stress the bolts, the upper upon holding-down | direction bedplate could yet move in any desired without hindrance. This was done by means of a washer of oblong sides of the form placed upon the carefully-levelled cells in the bedplates, which had bolts passing i and through them. The nuts were first put on screwed down by means of a hydraulic spanner with a short lever on that is, a heavy box spanner of which a ram the top of it, to the end hydraulic This assured HOLDING-DOWN BOLTS FOR BEDPLATES. was applied with a given pressure. Pig. 96. \\ SH O Pier. \ ' tened before rivetting as much as 3 in., and had tr bo constantly strutted with timbers to keep it in form. PORTABLE HYDRAULIC R1VETTERS. The plates forming the shell of the vertica columns varied in thickness in the case of the Fif and Queensferry central towers, from i in. at bottom to in. at in the case of 97 jj top ; and, Inchgarvie, froir Fig. in. at bottom to in. at yff top. The beams de creased in strength proportionately. The diagonal columns or struts in central tower: are of different shape, namely, circular top anc bottom, but flattened on both sides in order to facilitate their intersection with each other anc their entering into junctions top and bottom, when they are gradually changed into rectangular section It has been pointed out in the general description of the bridge, that the effects of the live load upoi the Inchgarvie cantilever are different from those in the Fife and Queensferry piers. The diagonal struts in the former case are therefore very much stronger than in the latter. The bottom and top plates are 1J in. in thickness, while the corner and side plates are 1 in. thick. The intersection of these two struts at centre of the tower is very heavy, some 80 tons of metal being massed therein. The inside beams are of corresponding strength. These diagonal columns were rivetted in the case of Inch- garvie from top to bottom by a special machine ol similar design as that for the vertical columns, but more difficult to work on account of the angle at which the machine was placed. Meanwhile, steam derrick cranes were erected on platforms raised some 30 ft. to 40 ft. above deck, commanding the whole of the skewbacks, and these were now built with portions of the diagonal struts, the vertical columns and the struts 1 in cantilevers, to as great a height as could be reached by means of these cranes. All this work was put together as carefully as possible, the larger number of holes being drifted up, but it was only bolted together pending the necessary checks and correc- tions being made by means of theodolites. This setting out was a work of no small difficulty, seeing that the members had to be set, not oiily to an inclination towards the point of intersection, but had at the same time to follow the uniform batter of the vertical columns, and had therefore a strong tendency to lean to the centre of the tower. So soon as the vertical columns and struts had been built to a height of about 50 ft. above deck, to which, in the case of Inchgarvie, had to be added the central ties, preparations were made for the construction of the lifting platforms, by means of which the central towers were raised to their full height. A staging, reaching on each side, north and south, from column to column, about 25 ft. in width, was raised from the deck to a height of about 38 ft. above the level of the staging, and upon this a pair of longitudinal girders were built. These girders were about 190 ft. long in the case of Fife and Queensferry, and 350 ft. long in the case of Inchgarvie. (See Figs. 101 and 102.) There were four girders one to each side of the vertical columns placed 18 ft. 6 in. apart, with angle cross bracings top and bottom, and diagonal bracing between top booms on one side, and bottom booms on the other side, alternately. The main booms, D D, Fig. 101, and most of the vertical angle bracing, were permanent work, being, in fact, the booms belonging to a portion of ties 1 in the cantilevers borrowed for the occasion. This plat- form and all its details are shown in a large number of the text illustrations as well as plates. During the time these girders were being put together, a strong box girder CC was built on a staging between vertical columns east and west, which girder passed through openings left in both columns, and projecting outside of each, to the extent of about 4 ft. or 5 ft. For this purpose one plate was left out on each side of the vertical columns during the time the girder passed aloft. This girder in its turn was supported upon a slide- block inside' the vertical column, which block was attached to a cross-girder B B. This cross-girder was "f double box section, all in plate, and in ids turn was supported by a number of pins about If in. in diameter, which passed through girder and through holes drilled for the purpose in four of the H beams of the vertical columns. Immediately below this box girder, and at a distance of about 1 ft. from it, was a second box girder of the same dimen- sions A A, and held up in the same manner by a number of pins. Upon the lower girder was placed, on a rocking underside, a hydraulic rani G G 14 in, in with a stroke of a little over 12 few diameter, in., every feet of lifting to the extent of the batter On the inside of the platforms at each end were the anil rain the box of the vertical which is 1 in about. hoists cylinder passing through upper tubes, 7i (See worked by wire ropes from winches placed The head of the ram acted means of a girder. by Plate IX.) on deck, and all plates, beams, and other material the swivelling cap immediately upon cross-girder With every few feet of lift these platforms had was brought up by means of these hoists and dis- CC from column to column. The of to be which was done passing working pushed together, by hydraulic tributed over the platforms. (See Figs. 104 and these as girders and rams was follows: The lower rams also, and this accounts for the number of 105.) Two-ton and 3-ton derrick hand cranes were box girder was held by a sufficient number of pins slide-blocks mentioned above. found the most kandy for the erection of the to the total it. The : carry weight placed upon ordinary routine in lifting was as follows different members, but a traveller, or Goliath, soon as a small of As amount pressure water was From a level position of the platforms the cross- worked by hydraulic power, was also used. allowed to enter the the latter lifted ram, the cross- girder in the north or south columns was lifted first When a lift had first been made, the first work, and it the box small girder C, with to a 6 in ; next the other end was lifted 1 ft. then the as a was to in the two girder B, ; rule, put closing plates to extent. The could then be withdrawn from the end 1 ft. until pins opposite ; and so on sixteen lifts each column which had been left out to allow for and the lifted in. or 12 as the had been last girder B, girder in., made, when a lift of 6 in. at the end the passage of the cross girders. The inner part case be. The were then driven which might pins through commenced the lifting made the platform of the rivetting machine was then drawn up, the the sides of the into holes girder B newly exposed, level again. whole machine fixed, and rivetting was at once and the beams and the let down that When the had in the first instance commenced while above the weight upon platforms ; platform a section The was then allowed to on girder. pressure pass been lifted to a sufficient height, the rivetting was added to the vertical tubes and the diagonal the of the the to]) ram, and cylinder was drawn up cages were suspended from the under side of the struts. The platform on Inchgarvie being of so to the with it the lower box in ram, bringing girder A. platforms, and subsequent lifts they were always much greater length, and weighing fully 700 tons, Arrangement of Hy draulic rams & girders For liFting the platforms in Central towers. HYDRAULIC HAMS AND GIRDERS FOR LIFTING PLATFORMS IN CENTRAL TOWERS. When the holes in girder and beams had come drawn up with the platforms. (See Plate IX., had to be provided with two additional supjKirts, of carried the opposite, the pins were driven in, and the same rivetting cages on Inchgarvie.) This cage simply and these, course, were upward same process could be gone over again. consisted of a stout circular wire cylinder being as the vertical columns. The arrangement as just described was placed in placed round a rivetting machine, similar in con- The water pressure for lifting was supplied by a each of the four vertical columns, and in the case struction to the one described for the horizontal special set of purnps which produced a pressure of was of Inchgarvie into the central ties as well, thus tubes, but hung vertically. Inside this cage the 35 cwt. to the square inch. No accumulator giving six points of support there, instead of four. men worked witli perfect safety as regards falling used, but the pumps simply forced up the rams gradu- The longitudinal girders were now placed upon themselves or dropping things down on those ally. Under this great pressure the cup-leathers in slides on the top of the cross-girders passing from working below. (See Figs. 106 and 107.) in the hydraulic rams and the leather washers caused side to side, and the tops of the girders covered The portions of the rivetting machine inside the the pipe-joints, frequently gave way and deal over with cro.jS-timbers, and decked with planking vertical column were not drawn up by the lifting of much delay. Frosty weather also did a great 3 in. thick. Thus there were two platforms about the platform, but were lifted separately subsequently. in the way of freezing pipes to hinder the work, of 25 ft. wide by 200 ft. long, or 350 ft. long in the The length of the plates in the vertical columns but after once the men had got into the way case of Inchgarvie, embracing completely and being 16 ft., the lifts of the platforms were of the working the plant, things went more smoothly. of witli projecting to some distance beyond the vertical same length. The first lift the Inchgarvie platform took, in the columns. Figs. 103, 104, and 105 show various The vertical columns were always built above one thing and another, nearly eighteen days of and 1887 ; while the positions and details of platforms. the platforms to any height which could be reached months January February, of of the same At the starting-point just above the skewbacks with the cranes or other means at disposal, while last lift, on the 9th August year, in five hours. With the batter these platforms were some 110 ft. apart, centre to the diagonal struts were at times built above, at was accomplished vertical columns and other side membeis centre, approaching each other, of course, with times below the platforms. which the have towards each other, it is easy to understand easy to handle. The men also had become so tower, and a new start upwards could be made ironl ' that, independent of any weight which was im- familiar with the work that they knew exactly what a fresh fixed base. At this stage a prodigious posed on them, they would be liable to deviate was required, and made little account of the height amount of work was done, immense quantities of from their true position. It was, therefore, neces- at which the platforms had now arrived, namely, material were drawn up the hoist and distributed on from to ft. sary time time, that is every 30 ft. or some 200 the top of the platforms where the platers, working 40 ft., to secure the members by the interposition At the next halt a great deal of work required to on tall ladders, bolted up beams and plates often of temporary struts or ties either in the shape of be done, namely, to build in the crossing of the 25 ft. above the platforms. Between the top of the lattice girders or of timber balks, and even timber diagonal struts in the centre of the pier. This for platform and the bottom, men were at work remov- trusses. Thus, after two lifts had been made with obvious reasons could not very well be done above and which came in ; ing replacing temporary bracing, the platforms, the diagonal struts in the central the platform, but some 20 ft. below. In the case of the way of the diagonal struts as they were built Oolialh Goliath towers had not only deflected downwards by their own weight, but had also deflected towards the centre line of the bridge. It was not possible to go any further without putting them right, and this was done by girders placed both longitudinally and transversely between the struts, and using hydraulic rams to push them apart. In the case of the vertical columns the same difficulties arose, and here strong timber struts were interposed. For the same reason, the first diagonal bracing between these columns was kept up as close as possible to the platform. (See Plate X.) Nor was this the only matter requiring care, for although these columns might be kept the proper distance apart from each other, yet might they also both deflect in one direction, be this east or west, north or south. With the heavy platforms carried on these comparatively unconnected members, a strong wind from one side or the other could pro- duce serious distortions and deflections, and the rivetting up of the vertical columns following so close upon the rise of the platforms, made them so stiff that it was not easy to deal with them. In checking the columns, reference was always made to the centre line of the bridge, which was thrown upon the cross girder which carried the platforms, and measurement from this centre was taken to each side. That side which deviated least was first dealt with and pulled or pushed to the right posi- tion there it was held wire ties or timber ; by rope struts, and the other corrected subsequently. This cross-girder itself was used for pushing the columns apart or in, one side being fixed for the time and the other left loose. ERECTION OF TOWERS. The first thorough correction was made at the top of the first vertical wind-bracing between the 80 tons of steel on Inside the the men were columns, where a solid plate girder passes right Inchgarvie this crossing contains up. columns, hydraulic vertical tie at for the next lift and the across, which carries the internal viaduct girders. each side, and at the crossing of the busy preparing examining at the and these in the This is shown in Plate X. The large gussets were centre, and the horizontal bracing occurs same caps, leathers, pipe joints. Below fixed to the columns, and the booms of the latticed point, a very intricate piece of work required to be cages and inside the tubes, the gangs of machine other which could done girders brought up to them. But the gussets were done. rivettors vied with each get for to the not yet drilled, and only after the position of one Here the vertical columns could be corrected the quickest, a premium being paid squad horizontal that its section first. below the column had been ascertained and corrected, these position north and south by means of the had done Again, holes were drilled, and the corner booms fixed. bracing which runs longitudinally from one vertical cages, men were replacing diaphragms and other to A fixed point being thus obtained, the other column column to another, intersecting the crossing of the details of the structure which had been removed still lower was either pushed out or drawn in as the case might diagonal struts. A pair of horizontal bracings are allow the lifting girders to pass, and be, and the booms fixed in the same manner. also placed here between the four columns as shown down, squads of hand-rivetters were rivetting up such rivets By this time the platforms had already approached in Fig. 4, Plate III. A strong framework, similar beams and diaphragms, and putting in Besides each other to half the original distance, and all the to the one immediately above the circular granite as the machine had not been able to do. to temporary girders became much shorter and more piers, thus closed the lower half of the central these a host of other men carpenters put up all an A an initial stress was them stages, gangway.:, timl>er stifl'eners, floors, and put upon by inter- horizontal cross-girder between trp junctions (the between the " sorts of things; men attending to the rivet furnaces posing hydraulic cylinders timbers two latter not shown in the engravings). of and trying to keep the machines going which put in and bottom booms girders, and filling the space The main strength of this junction lies in a their eighty to ninety rivets every hour, electric made with hardwood bloclrs. number of very large webplates carried on each Blocks were now laid down on the of the lightmen shifting lamps, putting in carbons and top plat- side of the centre in direct continuation of form in the centre line of the lixing fresh cables, and finally the hundred and one top members, and the webs of the top members. Inside these the bottom men who never seem to do anything, and yet cannot the vertical webs of booms, the flange are the starting-plates, or horns, as they were of same laid and so soon somehow be spared. angles the down, as the popularly called, of the diagonal struts, and outside were somewhat At last the tops of the platforms have reached top junctions advanced, they were them those of the first inclined tie in bay 1 of (he their final and can no connected at each end. The object was to cantilever. stiff beams position ; they go further, up Diaphragms, supported by relieve the as soon as of with a although the superstructure itself has to rise some platforms possible any gradual change from round to square, the members. The vertical it 20 ft. more. (See Plate XII. and Fig. 108.) The weight from top brac- connect with the vertical column. The flanges were then and in these the webs of the of the of two platforms by now have come so close together ings put on, top booms the top members are carried that the inner hoist-frame on one side had to be top booms placed. The girders could now carry right through, but the flanges of the bottom booms was as removed previous to the- last lift. The long box themselves, and rivetting commenced soon are replaced by extra plates and heavy angles. had been fixed and Most of of girder now projects a long way outside each as the top junctions securely the rivetting the main webs was done by vertical As there a column, and stands quite clear above them; the joined to the columns. was ordinary hydraulic rivetters, but a large number whole platform looks as if a heavy gust of wind great deal of work to do upon these top junctions, inside the cells, by small rivetters at the 3-ton would lift it up and throw it over the side. The they were completely surrounded by timber frames pressure of similar construction as those used in with last length of beams and the closing lengths of the covered with boards, and provided windows the cells of the skewbacks. The top junction is before can and a number of electric Thus shown in 109 and 110 in elevation and plates require to be measured they be large lamps. pro- Figs. plan, Fig. 105 Fig. 106 and requires no further explanation. The rivet- ting of the top member between vertical columns was now pushed on as much as possible, and, as soon as completed, the working platform was transferred to the very top of these girders, and the removal of platform girders and all hydraulic lifting gear, commenced. This was all the more necessary since it will be remembered the platform girders were made out of portions of the first inclined tie of the and was now | cantilevers, at once required to fill its proper place in the structure. Many of the plates and illustrations show details in connection with the lifting plat- forms and the work carried on upon them, but the space here is not sufficient to enter into description of them all. The removal of these platform girders, many HYDRAULIC TUBE RIVETTING MACHINE. hundred tons in weight, with all the odds and ends of a working platform upon them, was a work 'vhich cut to length. Once more the columns arc care- tected the work could be carried on day and night, caused no little anxiety; for upon nearly every fully set to the centre line of the bridge and to and it was necessary, for every beam and every portion of the structure below, work was carried on north and south, and the levels of all thd beams plate had to have its correct measurement and shape by scores of men to whom the fall of a small bolt in the columns taken. taken before it could be made. The ends of the or nut from that height might cause danger to life While these are being got ready, the gap of diagonal struts, changing from a flattened round or limb. The year in which the central towers about 9 ft. between the two platforms is covered into a square, had to be templated in every plate were erected shows the greatest number of fatal over, and only one platform exists now of more ' and beam to make an exact fit. It will give an accidents in any one year, namely, 17, while the than double width. idea of the magnitude of the work when it is stated average over the seven years is only 9. The longitudinal were stif- that these wooden buildings, of which there are platform girders TIIE CANTILEVER. a of ft. THE MEMBERS FORMING fened and trussed by link chains stretched from four to a pier, erected at height 360 above their of support to support. These chains were portions of the water, were about 24 ft. square and fully 35 ft. The bottom members from points junc- are not curved but are the Hammersmith Suspension Bridge, bought up high, with three floors at different heights. tion with the skewbacks not of such line to the first bottom by the contractors, and lai'gely made use of here The top junctions, although impor- carried in a straight junc- the in various ways. But the workmen would not tance as the skewbacks, are yet fully worthy of tions. At the centre of these junctions angle to the next consent to use the whole title due to them, for more than a passing remark. (See Figs. 109 to alters and the members continue straight the of the cantilever is some of them called them Hammer links, and 115.) Here are united two tubular members junction, and so on till end the becomes more others called them Smith's links; but it required a the vertical column and the diagonal scrut and reached. At each change angle of the sixth or last Cockney by birth or adoption to get the combina- five latticed members the top member in the obtuse, until in the middle bay at on tion. centre tower, the top member in the cantilever, the members are all but level. Looked plan 120 ft. centre to These links were passed under double timbers, the first inclined tie in the same, the highest of the bottom members are apart, and the at and 32 ft. 2 in. at the end right under the two girders of each platform, the four T.-ind-bracings between columns, ceutra skewbacks, GCi i I O1 Pk 02 ^5 H W U> G1 n HH U CC DETAILS OF JUNCTIONS AT TOP OF TOWERS. . 109. 113. Section at B.B. Fir) Fig. 110 Section C.C. on either posts the centre lines being straight between thcee outside angles side in the same manner to be adopted to forward the work. A cage is done in the case of I two points (see the plan in Plate III.) The diameter as the flanges of the top about 19 ft. square, and consisting of a number of these members at the skewback is 12 ft., and the members when passing the heads of struts and ties of sections each 8 ft. in length, was placed upon form circular, and the same form continues till th in the top junctions. the bottom member. (See Figs. 1(15 and IOC, and is 6 ft. At the of struts and ties Plate It so constructed that each sec- end of bay 4, where the diameter 6 in. a crossing large and strong IX.) was gradual taper being maintained throughout. Be- gusset plates are rivetted, into which are attached tion could be taken away at the back and placed tween the end of bay 4 and the centre of bay 5, the so-called vertical ties. This is clearly seen in in front, and this operation was performed by the form of these members is rectangular with a Plate III. These are also rectangular lattice a hydraulic crane placed on the top of the curved outside, and after this a plain rectangle on girders consisting of four booms, or in the lighter cage itself. This crane has a jib of fixed length, all four sides of varying height and width, until at ones of four angles cross-braced on all four sides, which it could not alter, but it could slide up and the end of the cantilever the form is a square of 3 ft. and to the lowor extremities of these are attached thn down the top of this cage by means of hydraulic each way. The thickness of the plates in the bottom bottom members by means of bent angles and rams on each side. It could also slew completely members is 1^ in. at the skewbacks, gradually de- gusset plates. These vertical ties, although not round. The forward part of the cage was used by of creasing to | in. at the ends. The same mode attached exactly midway between two of both the platers for building up the tube, the beams construction with longitudinal beams and transverse members' junctions, serve to prevent undue deflec- and plates and other parts being first brought diaphragms of circular or other shape is followed tion in these members, and in the first three bays within reach of the hydraulic crane and then to the end. In all the bottom junctions the main of cantilevers serve to carry the weight of the swung round into place. The nearer portion of strength is concentrated in strong webplates into internal viaduct by means of a plate girder across, the cage contained the same rivetting machine which the circular tube is gradually carried over, stiffened by diagonal wind bracing. which had already done service in finishing the curved plates being placed on the outside of these maintain the circular on the W. Cross T/6. webs to appearance J. Section cf Fig- Cross Section Struts in Cantilevers. oF outside of the junctions. (See Fig. 12(>.) To the Top member main webplates the hornplates of the ties pointing backward, and these of the struts pointing for ward, are attached. Except that the winding of the outer shell is perpendicular instead of horizontal, the construction of those junctions in principle is similar to that of the top junctions at the head of the vertical columns, but turned upside down. The changes in the form of section in the bottom members are indicated in the general elevation, plan, and side elevations of the cantilever in Plate III. The top members (see Fig. 116) or principal tension members are lattice of girders rectangular Pig. 118. Cross Section of inclined section, consisting of four main booms, which are ties in Cantilevers. braced on four sides. The webplates are carried through the whole length of the girders unbroken, only changing in depth and thickness, or in the number of thicknesses. The vertical side bracings angles alternately on one side and other side of the webs are double-crossed throughout. The horizontal bracing is not attached to the top and bottom flanges, but to a special plate attached to the web by angles on each side, and called the horizontal web. The horizontal bracing is also of angle bars, but for the most part in single or zig-zag fashion. The top flanges run right through to end of bay 5, where they disappear, the two web angles at top and bottom supplying a sufficient amount of section. DETAILS OF CANTILEVERS. Ihe bottom flanges run up to the top junctions only on the inside, but right through on the out- In the tension members two top and two bottom horizontal portion of the bottom members between side, the loss of section being made up here in booms break joint alternately, and all webs and I columns. For a length of about 64 ft. the bottom other ways. Like the junctions in the bottom flanges are double covered. The top and bottom member was thus rivetted up in order to stiffen it in the are members, the webplates top junctions cross-bracings are rivetted to the flanges, the side as much as possible, and enable it to carry itself stiffened or a.nd receive the of doubled, hornplates bracings to the webs. Diaphragms consisting of and the necessary plant at the point of it, unsup- with which a struts and ties, they form very strong angles on four sides and angle cross in centre are ported for a time until temporary support could I c stiffened bulkheads or framework, by diaphragms. placed at suitable distances apart. found for it. (See Fig. 105.) As soon as the ca^'O The inclined struts (see Fig. 117) are flattened The internal viaduct in the cantilevers is the same had got beyond the point of junction between to facilitate their intersection the on the sides with as described for the portion in the central towers. the bottom member and the first vertical tie, that their to bottom and ties and attachments junctions Figs. 119 and 120 show a portion of it in elevation is, at centre of bay 1 (see Fig. 121), gussets were top junctions. They are, however, changed inform and cross-section at the point where the viaduct is attached to the bottom members close to this in their extremities made rectan- and to the vertical columns altogether being supported in the centre of bay 1 (see Plate III.). point immediately the same as the struts in the central above the horizontal the gular diagonal The two figures are not drawn on the same scale, bracing between columns-, towers. number of are in- A : a chain of Hammersmith links fixed diaphragms placed but otherwise refer to the same point. and were up ternally where these changes occur, to keep the As the in the cantilevers become shorter between these two On these links a ttn:- spans j points. struts in The thicknesses of . of shape. plate vary the viaduct diminishes in strength of sections, and porary staging was suspended, by means which between in. and in. to Their of i according position. from the centre of bay 2 to the end of bay 2 in a heavy plate tie one on each side the tube construction is on the same as the other these ties also principle depth also. At the end of bay 4 the girders could be inserted. For strong tubular members on the circumference lap joints altogether disappear, and the four troughs are gussets were attached to both bottom members and butt at ends all 10 ft. joints plates being long, strengthened and carry the permanent way, being vertical columns. To the gussets on the columns breaking joint every 8 ft. with a diaphragm at both on the cross and on the other were attached, and to these were supported girders j gussets each Struts 1 and 2 are made of to and joint. up eight diagonal wind bracings between the cantilevers. (bolted horizontal plate ties, suspended struts 3 and 4 of six and strut 5 of plates ; plates ; All the various suppo rts of the internal viaduct immediately below the horizontal bracing girders on the four plates circumference. in the cantilevers are shown so clearly in Plate III at the intersection of the diagonal struts. A set of As seen in Plate III. all struts in canti- the cantilevers that it is not necessary to enter int f uther details. plate ties were also placed at the opposite are braced and stiffened by diagonal wind-bracing The diagonal wind bracings between the botton? lever, and balance thus established. These plate of box of four 1 were about girders shape, consisting corner members are a so of rectangular box c .instruction, ties, both horizontal and inclined, with double or on all 2 ft. of two thicknesses of in. angles single cross-bracing consisting of fuur main booms made up in the 6 in. deep and f four sides. These are attached to the struts in of the main webs of by longer girders by webs, flanges, and angles, and in plate, being, fact, portions and reverse One is the in 2. Previous to the attach plate gussets angles. girder the shorter girders of simple corner angles. They top members bay carried the other is in two of to the the bottom mem- generally right through, are double or single- braced on all four sides, and ment these ties gussets, halves and is carried across reverse the extent of several inches by strong angles are joined by heavy gusset plates at the points of bers were lifted up to and At the heads of order that stiffening plates. every pair intersection. They are joined to the bottom mem- by means of hydraulic rams, in they of struts a horizontal lattice is between to their own and girder placed bers by large gusset plates top and bottom, clearly might be able support any further which be them top junctions. shown in Plate III., plan of bottom members. weight might put upon The tension members are all of the lattice girder during erection of the first bay. Most of these with four BUILDING OUT OF THE CANTILEVERS. type main booms of T shape braced on appliances are shown clearly in Plates, IX., XV., all four sides. The section of the main booms is had arrived Shortly before the lifting platform and XVII. made of one or several vertical tie was up webplates, and one or at the point of intersection of the diagonal struts The lower portion of the first more with one flange plates, angles to connect both or columns in the central towers, a commencement then built, and a lifting girder laid across from At the of together. point crossing with the struts was made with the building out of the bottom bottom member to the other, and a platform built the inner flanges are cut away and the section thus members in the first bay of cantilevers. This on each side similar to those for the erection of the oat is made in up some parts, by a deepening of was done as yet by steam derrick cranes, but central towers, only so much smaller and lighter. the web anj a rams in by doubling and strengthening of their reach \vns limited, and other ir.cvns had Thess platforms were lifted by hydraulic tne vertical and the same the drilled in situ. This ties, by agency along junction was then at once put a tremendous strain upon the two top members, vertical columns, and while lift ing these in stages rivetted up, and thus a new fixed point secured which were then still unsupported, and though they of about two strut" 1 in cantilever and from which to further 16ft., the proceed out. (Plate XV.) bore their load well it is evideut that the building the vertical ties were built The use of In the the or of up. lifting- mean tima, top member, Jubilee this first half of bay 1, was a work of great after all the of as it platforms was abandoned this; work Crane, was popularly called (because it was anxiety, lest a heavy gale should cause some serious erection was done far more quickly and efficiently invented, or at any rate designed, about the time distortions. for this work. of the by the cranes specially designed Queen's Jubilee in 1887), had been erected As the top members were never intended to carry Meanwhile, the top members had been completed, on the top of top member. any load except their own weight, the vertical set of This of and a 3-ton hand-crane was up on the top crane consisted a square frame supported side bracings were not sufficiently strong to carry each vertical column. (See Fig. 121.) on two girders reaching over all four booms of the the crane without a risk of bending the bars. The viaduct girders in the central towers had top members from side to side. The girders were These bracings were consequently not only doubled also been put together by now, and a new platform of different heights, in order to get the platform by reverse bars running the full length with them, but was thus secured about the erection. on which the crane was and the the reverse bars were of a section double and treble half-way up j placed level, ' The viaduct girders were now built out by over- girders were placed on slides, so as readily to that of the ordinary bracing bars. Templates for hanging into the cantilevers, and a length of top allow them to move down the incline of about these bars were taken as soon as each section of member as well, these two last being built by the 1 in 4 when required. The crane itself had a the top member, was built up, and they remained in 3-ton cranes on top, and by winch and tackle horizontal jib with a reach of 34 ft., and could their places until the weight of the crane had passed wherever such could be used. All the material slew round, by means of a circular rack and pinion, beyond the next main support. Generally speaking for the viaduct level was hoisted to it, and for the to about 220 deg., or three-fifths of a full circle. this crane built all the members above the level ot top members, it was lifted right to the top. It was worked a pair of reversible steam the viaduct, and of course below that level also if by ! j The viaduct girders were strong enough to carry , engines, and had a large barrel capable of winding [ necessary. Its maximum lift was 3 tons, and with FIG. 119. ELEVATION OF INTERNAL VIADUCT. i rare exceptions no portions of the work were made heavier than about 50 cwt. at the outside. As soon as the crossings between struts 1 and ties 1 had been made secure a vertical support a box lattice girder, was raised from, that point square upwards in continuation of the vertical tie below, in order to give the top member the necessary sup- port. As this support formed no part of the finished structure it was made of iron only, but of fully sufficient strength. It required, however, both longitudinal and lateral support, and this was provided by carrying lattice girders at a point about two-thirds of the height between the crossings and the top members on each side, from the ties 1 to the vertical supports, and transversely from one support tqthe other. Cross ties of wire rope were also carried up between the supports. As soon as the supports had reached up to within a foot or two of the top members, a further length was built to the latter, which reached right across the supports. By this time and with so much weight on them the top members had deflected about in. in. rams were now 9 to 10 , and hydraulic arranged to lift them up from the vertical supports, and give them their proper position, and place them as much higher as would allow for the probable compres- sion in the vertical supports. Fio. 120. SECTION OF INTERNAL VIADUCT. Meanwhile the lower portion of the ties 1 had been built from the point of intersection down- for wire It carried its boiler the bottom member had been themselves, overhanging a length of 100 ft., and up about 400 ft. of rope. wards, brought even then to at self-contained. Sus- and the of bottom members carry the forward end the weight with it, and was thus quite forward, junction and ties at the end of the first built of a 3-ton crane and its load, but, as a matter of pended from the two main girders of the frame was with struts bay, ft. ft. in. But the bottom members also had safety, wire ropes were carried from the outer ends a platform, carried some 4 to 5 below the deflected, up to the top junctions on vertical columns. bottom booms of the top member, 64 ft. long and owing to their own weight and to that of the ! the and the bottom The top members also had to carry their own about 36 ft. wide, mainly supported on four light rivetting machines cages ' It to lift the weight unsupported for a length of nearly 100 ft. lattice girders. junctions. was, therefore, necessary members at this do tliis The lifting platform in the first half of bay 1 was The planking of this platform was so arranged bottom up point, jind J;p ' 123 only carried up to about 20 ft. above the level of that it could readily be taken up in every place the following plan was adopted (See Figs. the Tiaduct, and there it remained. (See Plates where required, the four lattice girders being so and 124): were attached near the ends XV. and XVII.) placed as to pass all struts and ties and vertical Four heavy angles as had been down The first inclined ties in cantilevers were now supports in succession, the flooring only requiring of ties 1 co far they brought ; of such as to brought down from the top junctions, being held to be taken up. The sides of the platform under these angles were length project ft. below the under side of the up and in position by means of timber struts be- the top members projected to within about 6 ft. some 6 ft. to 8 tween them and the vertical and of the end of the In the mem- bottom member; two heavy box girders were now columns, laterally jib. building top j in of under each of the bottom the lower apart by lattice girders from one to the other. (See l>ers, the booms of which were lengths about passed members, fixed to the ends df the four Fig. 122.) 24 ft., the crane could lift them from th viaduct one being angle-bars, was to hardwood The first struts had also been built up to some level below and place them at once in position, the while the upper girder brought up it a full the 20 ft. above the platform, and when the ties had platform allowing safe ground for the menlen who had packings, which gave bearing against bottom members. Between the been brought down to the point of intersection to guide them into place and bolt up the joints under side of the rams about 10 in. in diameter with the struts, preparations were made to make and cover-plates. The vertical bracings followed ! two girders, hydraulic rams in all other neces- ! The action of the good their junctions, Previous to this the positions next, and then the top booms, and were placed. hydraulic of out to the of struts, ties and vertical ties, were carefully sary work, and when both sides the top member being forced was, therefore, push upper members and the checked, both as regards their meeting in the tru were built and well bolted up, the e-ane was pushed girders hard up to the bottom a corres- centre as well as being the right distance apart forward 24 ft. on to the newly built section. lower girders downwards, thereby putting ' stress on the ties 1. from the centre-line of the bridge. Large gusset- The crane with platform and all necessary gear ponding tensile at a distance In the vertical ties in the centre of 1, a plates, joining all three members together, were weighed about 64 tons, which, placed 1, bay of the foui booms had been left then placed in position and the necessary holes of about 80 ft. from the centre of the top junctions, joint in each open into in such manner that this tie could bo shortened to ami to give them the elongation proportionate to viaduct by the top member cralie, swung and at once bolted on, while the a certain extent, its upper end at the crossing that weight. position, stage this there were outside the central when it was attached to being now an absolute fixture. By means of an With now, itself, required raising, two the of the crane for the moment and lifted when it arrangement of cross-girders and hydraulic rams towers, points established, position up, which was and which were of sus- was attached chains or wire ropes to the this joint could now be closed to any desired correct, capable again by the full which would have ulti- strut itself. extent, new cover-plates being, of course, required taining weight they to sustain in the structure. The tie staging was to stout rope tackle to make good the joint. mately completed hung next was to raise the mem- and let down the men on the ties All being thus prepared, a theodolite was placed The operation top by working in the centre of each bottom member, and these bers from the temporary vertical supports car- themselves. the of and this also As soon as the struts had been built to a were lifted, both at the vertical ties and at the end ried up from points crossing, up was done rams. The close under the junctions with top members of the inclined ties 1, by means of the hydraulic by hydraulic temporary point the of intersection and the latter had their checked rams, until the members had risen to the correct supports raised from points position by theodolites, carried to the members were used at the centre and, if were these also angle and a trifle beyond, when hardwood packings top required, they upon points in each case much lifted rams and then drifted were put between the girders, and wedges driven of every bay out, becoming by hydraulic pressure to be and when in correct were at once shorter and had removed, j in, so as to secure the maintenance of their posi- lighter. They up, position to want of material for a rivetted. Another fixed was thus secured, tion. Thus placed, the holes in the new cover- owing making larger point * FIG. 121. ERECTION OF CANTILEVERS. plates making up the joints in the booms of the number, frequently before the top members were and the first bay in cantilevers practically com- vertical ties were drilled at and the rivetted to bear their own once, joints up sufficiently weight . pleted. rivetted up. and that of the staging which was attached to them, The plate girder, reaching transversely from one The closing lengths of the booms of the inclined and considerable deflection in some of the longer > vertical tie to the other, and upon which are sup- ties 1 were also and made of sections was the result. the of the internal had measured, templets ! ported girders viaduct, them and taken to the shops. These lengths The top member crane could now slide forward meanwhile been put in place, as also the diagonal then cut at were and drilled, and once put into another section and build, not only the next section . bracing below it. The viaduct was then advanced their places, and the whole of the ties finished up of the top member, but also the upper halves of : over it and carried forward till it reached the first in and detail. struts 1. did not across the every part These take long. They were , trestle at end of bay 1, which reaches The effect of these operations then was : built from the bottom upward, in the same way as first bottom junctions and gives support to the 1. To secure the absolute correctness of the the inclined ties were built from the top downward. . internal viaduct at this point. position of the first bottom junctions as regards For the struts light square stages fenced on four So far completed, all members were at their the height above water, and their distance from sides were used, these being 15 ft. square and open correct elevation so far as this could be secured, the centre line of bridge. in the centre to admit the strut. The stages were but it was possible, and happened frequently, that, 2. To both the inclined ties 1 and the accessible of put upon by means wooden ladders laid from , owing to continued strong winds (no permanent ' a vertical ties that stress which would correspond bottom upwards or by rope ladders hung from the wind-bracing was as yet fixed) from one quarter, with their share of weight of the structure put up, top. The bars and plates were picked off the certain amount of displacement occurred. Thus, the bottom members at the end of but the last although might pletely, or closing lengths outwards always so much greater from the west than from the first be the distance were left to be measured and in the east has junctions proper apart always templeted something to do with it, the writer from each other, the centre of an situ. The which were attached will not take yet imagi- gussets by they upon himself to say, but appearances nary line between them might not coincide with the to the bottom members were already fixed and decidedly point in that direction. centre line of the but fall to one side or rivetted to the and it bridge, latter, remained, therefore, With the corrections in the positions of the struts the other. the same to in Precisely tiling might happen only erect the girders their places and take and bottom members, the first bays of the canti- in the case of the inclined and the the for struts, top templets the closing ends. While they levers were now completed, and, except in so far members thus lie to one side or the other of the were erected were wire being they hung by as the elasticity of the steel came into play, all the true centre line. to the internal viaduct. to ropes Previous this, points were as fixed as if each was resting on a Nor was the wind the factor that could the only however, exact position of the bottom mem- solid masonry pier. produce such a result, for the fact whether the sun bers had to be ascertained, and, if not correct, wire The duties of the survey department in connec- was shining on the east side or the west side of the rope ties attached between bottom members and tion with the erection of the cantilevers were of the bridge made a material difference. On the sun girders by means of union rews or timber struts, heaviest kind. The work had to be carried on in the that side of appearing plates on the tubular worked witli wedges or small hydraulic rams, had the most exposed positions and in all weathers. To members on which its fell would rays expand, to be employed to draw the bottom members in or Mr. W. N. Bakewell belongs the credit of a great while on the other sides the remained as j plates push them out, according to requirements. This achievement, and it is not too much to say that to ;. "'" ^^^^^^^iiS^^^y}J- ' '"'-'- Fio. 122. ERECTION OP CANTILEVERS. were. This they produced, therefore, a bend away done, the templets of the booms were taken and his courage and decision and promptitude in fixing from the to an extent not sun, inconsiderable, but, the girders completed. The same process had to points, is due the saving of much time and much of in its action with be course, only temporary ; for, repeated at every point of attachment, that is, expenditure. sun to and the turning south passing to west, the every half-bay out. The position of the inclined From the first bottom junctions struts 2 were members rot only became straightened again, but struts with regard to the centre line of the bridge started upwards, and from the first top junctions became curved in the direction. opposite was corrected in a precisely similar way, and by ties 2 were started downwards, in repetition of the Errors in and faults in measurements construction this means was achieved the successful building out operations already gone through in the first bay. might, of course, also produce similar and per- of these arms, nearly 700 ft. in length and weighing The bottom members were built out and the manent results, and it was therefore necessary to some 5400 tons, with an error of only 2 in. For internal viaduct brought forward. Upon the latter take to fix the so far as it could be steps position an error there is, and, curiously, it exists in nearly were now erected upon a staging sliding on the done. all the six cantilevers, and in the same direction, rail troughs two steam cranes with movable The diagonal wind-bracings between bottom mem- namely, to east. Whether this is due to the pre- derricks standing side by side, each being worked the first bers, of which pair starts from the skew- vailing westerly winds, and the fact that the total by a steam winch placed some distance behind. backs, now required to be dealt with. pressure from the west upon the structure during a Wire ropes were exclusively used by these cranes, neither bottom members nor inclined struts As twelvemonth must be probably fifty times as great which, owing to their position, were called the twins. had ever been laid together in the relative posi- as the total from the east, or whether the fact that As the Jubilee crane, resting on the top members, tion, the wind-bracings could not be built com- the lateral deflections due to the sun's rays are built all the work from near the viaduct level so the twin cranes built ev. rything from union screws being used in the of hydraulic hydraulic rivetters, while the struts were rivetted upwards, j place by that level downwards. cylinders. by hand only. The main booms of the ties were ' Up to this time most of the material of which The erection of bays 3, 4, 5, and 6 was simply rivetted up in the yard as far as could be done by the members were built was lifted the hoists in routine work of the work and little more than the and brac- by j repetitions gone through machines, joints the central towers, and brought forward on tempo- and so much more easy for the reason that not ing bars were left to do after erection. Of the rary lines of rails to within reach of either top only had the distances, both vertically and horizon- internal viaduct also as much as could conveniently member cranes or cranes on the viaduct. From tally, between the members become so much less be got at was done by hydraulic machines, and the this point forward only the light material, such as great, but also because the men had become so skilful rest by hand. bars, angles, and other things, were sent up the and so accustomed to their tasks, that what ap- The booms of the wind-bracings were also rivetted hoists, while all the heavy booms and plates were peared at one time to be insurmountable difficulties together in the yard by hydraulic machines, and as placed on board one of the steam barges, and and hazardous undertakings, had now become mere they decreased in weight further forward they were hoisted up by one of the twin cranes to the viaduct child's play, and was done in those exposed posi- rivetted, at times in the full square, at others tops level, and thence were taken by the Jubilee crane tions as easily as if the men were standing upon the and bottoms, thus leaving the side bracings only to to the top. Somewhat later, again, when the top floor of an ordinary workshop. be completed. 9367 THE " JUBILEE CRANE ON TOP MEMBERS OF CANTILEVERS. members had still nearer to the water, The rivetting of the work followed the erection In the same way the lattice box girders between approached j the material for for of rivetters were the struts were also dealt with could be lifted these, and the upper portions of so closely, that many squads ; they struts, and ties, was lifted by the Jubilee crane out working upon the extreme ends side by side with straight into their places, the joints only and the of the barge, and swung into place at once, thereby the erectors. In the case of the tension members points of intersection requiring to be rivetted. saving much time and labour. all the main joints were rivetted as soon as pos- The top member was rivetted in all parts by In the erection of the bottom members in bay 2 sible after erection, and where such could not be hydraulic machines wherever it was possible to get the temporary attachments necessary to hold them done, all joints were bolted up with specially pre- the machine applied. For this purpose two or three up in position were carried partly to the point of pared turned steel bolts. light timber stages followed at the back of the or intersection of struts 1 and ties 1, partly to the In the bottom members the hydraulic rivetting Jubilee crane, and here two three rivet-heating first top junction, and there attached to heads of machine was carried forward to beyond the end of furnaces were kept going to supply the various struts 1. the third bay, after which all rivets were put in by machines going below, the hot rivets being dropped into Hammersmith Bridge links were used for the first hand, particular care being taken to have all the down a long pipe, the end of which was stuck furnaces and wire ropes for the second, no plate-ties being work thoroughly well bolted up, and to put the best a pail with ashes at the bottom. These air. thus required. Later on still wire ropes were capable and most trustworthy hands to the job. All the were heated by oil and compressed It was of with to in first instance from dealing most of the lifting required, tension members were almost exclusively rivetted necessary bring along the the deck to the of the towers, and then to but with no result. Only divided by a of some up tops mid gap each side down the cantilevers, not only the pressure Queeiisferry Fife. 350 ft. it was now possible to take up a position in and central towers 481(5 a of pipes for the water working the hydraulic rivet- Bedplates tons each gale wind, and by fixing a point on the oppo- cantilevers site cantilever ters, but also for the supply of compressed air and Two 10,816 ,, end and another point fully half a oil to the furnaces. The oil was brought in pipes mile further back on the shore, try to see what the connected with a tank on the top of the central Total 15,632 lateral deflection might be. But, whatever its tower, and run down to the furnace tank by amount, it was too small to be noticed by the Total tonsfor both naked ; nor could movement be felt gravity. 31,264 eye any except a slight vibration whenever an extra heavy gust of wind would hurl itself against the solid face of steel plates. In setting out the centre lines in the vertical sense of the bottom members while building out plate by plate, allowance had been made at every junction for the natural and unavoidable deflection in the whole cantilever as a mass. This was, of course, also done in setting out the internal viaduct. It was intended that there should be in the free cantilevers a camber of 10 in. at the end posts when the cantilever was completed that is, the line of rails at the end post would be 10 in. higher than in the central towers when no load was on the bridge. But to get this it was necessary to set each section higher by so much as it would deflect by the addi- tion of the remaining sections further forward. The point aimed at was, therefore, set another 10 in. up, or 1 ft. 8 in. altogether. This was, of course, entirely a matter of calculation and of judg- ment, and in the end the cantilevers arrived at the in which were desired to be. for position they Temporary angles lifting It remains now to tell how the central bottom member girders were erected and the final connections made. The end posts are hollow boxes about 4J ft. deep and 3 ft. wide, by 40 ft. in height, and are closed on three sides, the fourth side towards the central girder being open. The bottom members project right to the end of the post, while the top members stop short at the closed or inner side, except the webplates, which, in the shape of large gussets, are also carried full to the open end. So far the four free cantilevers are exactly alike, but in the further arrangements they differ considerably, as will presently be described. Saddle For Trestle The end posts of the two fixed cantilevers end of Bay 1. where they rest in the cantilever end piers are different from the above. Here the posts are re- placed by a large box about 8 ft. long and extend- ing over the whole width and height of the end of the cantilever, out of which an arched way has been cut to allow the passage of the Wains. An end elevation of this box is shown in Fig. 23 on a preceding page. The object of these boxes has been already explained, and will be again referred to in connection with the expansion movements provided for at this point. They are filled with cast-iron bricks and punchings and other scrap all laid in asphalt poured in hot and firmly set, thus preventing shifting and at the same time making the box water-tight. About 1000 tons of dead weight is placed at these points over and above the weight of the steelwork. The central girders have already been described as having a slightly raised or curved top member of form that is to it is polygonal ; say, straight from one support to another, a kink taking place at the point of support, in the same manner as the bottom member in the cantilevers. The bottom member is straight. The two are connected by eight pairs of cross-bracings on each side, inter- each other at the centre and of HYDRAULIC LIFTING ARRANGEMENT FOR BOTTOM MEMBERS OF CANTILEVERS. secting consisting struts and ties. The girder is 350 ft. in length, Central Girder Cantilever Direction of Train running H "a O . i,"rt 3 O T3 -^ a; O r-O rt 11 IB 3 a si a S of a> P I tf I in * H S n PH ' 3 S PH H '" ^ 5.2 S g Wfc _g 3) S .p, a O If ill M H -S 3 CO H - O o fl to ". = 52; O _a 2-a-s O O CO J lil'sJ i i H<1 W i 18 P O >4H * '-3 ts n 2.S S ^ m PH w J HI I ! O i P < CO Wtf q O Ofe H O C o fcottom, allow a horizontal movement of the whole In the first instance, heavy temporary platform completed, and half a tie and half a strut bc-longing girdor round the centre of the pins, while yet girders had to be attached to the under side of the to each of the other two halves were luft incom- allowing no lateral movement of any kind except bottom members in cantilevers projecting over plete. (See Fig. 136.) that which may be due to the mere hair's-breadth towards the central girders, some 25 ft. (See In setting out from the ends of the cantilevers of play in the slide-block. Fig. 135.) Upon these were laid cross-timbers, the wedges had been set in such manner as to give At the Queensferry and Fife ends, however, and a strong platform was formed upon which the bottom booms an inclination upwards, which, these blocks are absolute fixtures, steel packings the first half-bay of the central girder was erected. if no deflection had occurred, would have given the having been placed into the two 12-in. spaces which This had to be done, however, outside, and about girder a camber of 12 in. The deflection, however, are left open on the Inchgarvie ends; and while yet 6 ft. away from the end posts, because all rivets arising from the increasing weight overhanging, the same circular horizontal movement round the inside the end posts, and through those portions reduced this to exactly the camber prescribed centre of the pins is possible, both longitudinal of the central girder which would have to be namely 3J in. and lateral movements are prevented. Should it drawn within the end posts, required rivetting The lengths of the bottom booms of the girder therefore happen that one cantilever has to sustain up. All these holes were countersunk, and the were fixed i;o as to leave at the temperature of the impact of a heavy gust of wind while the other rivets made flush. The cups which had to re- 60 deg. still a gap of 4 in. clear between the ends. is not so affected, the deflection thereby produced ceive the rocking posts were meanwhile placed in This was necessary, on account of the possibility of can take with it one end of the central girder and position, and carefully set and levelled, and next the temperature rising considerably above 60 deg., leave the other in its original position without the rocking posts, weighing nearly nine tons each, which in the middle of September, when the south putting any side stress upon the girder itself. were hoisted up by special tackle and shipped into central girder had been expected to be connected, It should be mentioned that the lower bearings their places, and lowered into the cups or sockets. was quite possible. For the north central girder, at Queensferry and Fife in which the pins rest, are Into the tops of the rocking posts were now placed which was to have been connected a month later, not bolted down to the cantilever ends, but have the half-balls or knuckles with flat tops, upon which the same gap was left for a temperature of 50 deg. play sufficient to allow horizontal circular move- the under side of the top members of the central only. ment round the centre of the pins in the inter- girders would come to rest. Thus far the Inch- In the top booms a somewhat larger space was left, locking arrangement above described. garvie ends. The Queensferry and Fife ends were tapering in shape from about 10 in. at top down to All in the main structure have dealt that no 6 in. at of the for here expansion joints similarly with, except rocking posts, bottom webplates ; wedges now been considered, with the exception of that in but only the horizontal pins, had to be placed. The had to be inserted. the cantilever end piers. At this point expansion shipping in and fixing of slide-blocks and vertical As it happened, however, delays occurred, and and contraction to the amount already stated can pins had also to be done at the same time. As the south girder was not connected till October, take place longitudinally, but in no other direction. soon as the half-bays of the girder on each side and the north girder in November. This is the only occasion where rollers are used for were built, the whole portion, weighing about The connection of these central girders was an and the of these is 42 was shifted back into its inside the of a character for here bearings, arrangement clearly tons, place operation most interesting ; shown in Figs. 133 and 134. The lateral or end post, and connected up and also drawn tight by a greater use was made of natural forces than in vertical movements arising here are prevented by a number of chains and wire ropes passed round. any other portion of this bridge. the following means : Heavy temporary ties were now attached at the As it was essential to have the temporary plate The steel canting A is a fixture to the under side centre of bay 6 in the top members of the canti- ties, which still held up the weight of the two of the extreme end of the cantilever, here in form levers at one end, and at the centre of bay 1 in the halves of the central girders, fully under control, a of a box. This casting forms the head of the roller top members of the central girders. (See Fig. 130.) small brick furnace, heated by oil and compressed bearing, but also bears a side flange, which is set These ties consisted of three layers of plate, each | in. air, in the same manner as the rivet-heating fur- hard against a heavy cast-steel plate B, which is in thickness, by 26 in. in depth. I'here was one naces, was built round each of the four plate ties bolted down hard to the masonry, and carries a such treble plate-tie to each side of a top member, at each end, just above the end posts, and every- side flange similar to that of A. As the same thing or four altogether. The ends were fixed to large thing made ready for instant lighting of the same. is arranged on the opposite side, it is clear that gusset-plates and rivetted up, but the middle joint Arrangements were also made to draw together by lateral movement can only take place to the amount was bolted up by special turned steel bolts, 1 in. hydraulic pressure the two bottom booms at the of play between A and B, which is practically nil. in diameter. There were about seventy-four bolts gaps in the joints in centre of girders, in order to Again, on the top of the bottom end girder of the to each joint. be able to give every chance to the work being cantilever, outside the loaded box, a piece of steel To the ends of the bottom members, both in done expeditiously. C is laid, which touches, or nearly touches, another cantilevers and central girders, thick cast-steel The temporary connections between the booms, cast-steel plate D, let into the masonry of the pier, plates were fitted, leaving a wedge-shaped space which, however, allowed full play to expansion and and bolted to it by holding-down bolts. Indepen- between them, the wide end downwards, and this contraction, were as follows : (See Figs. 137, 138 dent therefore of the counterpoise placed at this end, space was carefully templated, and steel wedges, and 139.) which prevents the cantilever lifting under any con- about 9 in. wide, two to each side, were fitted in To the bottom flanges of the bottom booms, large ditions of train load or fixed load, there is provision and set up hard. (See Figs. 128, 130, and 131.) and thick plates had been bolted on each side of made to prevent its rising should an unusually heavy Everything was now ready for continuing the build- the gap, extending over the whole width of the bot- gust of storm-wind strike the end of the free ing out of the girders, and half-bay by half-bay was tom flanges, and projecting to some 7 in. on each cantilever, and thereby try to lift up this. This it speedily added, some delay being caused on account side of them, and upon these plates other plates, cannot do, but the stress causes an upward deflec- of all the joints in top and bottom booms having which reached across the gap. They were fixed on tion in the fixed cantilevers within the limits of to be rivetted before much weight was added for- the Queensferry and Fife sides, but could move in the elasticity of the metal. Neither of these ward. and out at the Inchgarvie ends. For the temporary two arrangements interferes with the longitudinal The top member cranes, which had by degrees connection there large slot-holes were provided, into expansion or contraction, which are facilitated by made their way downhill, doing all the work since which bolts 1J in. in diameter were fitted, but were the arrangement of rollers between the castings E the fifth bay had been completed, as the canti- not put in until the time of making good the connec- and F. All movements have now been considered levers had by then narrowed so much that there tion, the slot-holes being 4 in. long, while the holes in detail, and since they are of such vital importance, was no room to bring the twin cranes any further, in the plates, which were parts of the booms were it will not he superfluous to recapitulate them here were now relieved of their heavy platforms under- simply round, of 1J in. diameter. Once these bolts once more in toto. neath the top member, and of other temporary were driven in, the gap between the booms could 1. Expansion and contraction produced by changes appliances they carried. Thus made lighter, they not be increased, but in case of increase of tempera- in temperature provided for by the sliding bedplates, were moved on the temporary plate-ties, and thence ture the slots would allow the gap to decrease and by the rocking posts at one end of each central on the top booms of the central girders, where they prevent buckling in the booms. The arrangement girder, and by roller bearings in the two cantilever now began to climb up the curved booms towards is clearly shown in the illustration. end piers. the centre of the span. (See Plate XIX.) These The temperature had been watched for several 2. Lateral deflections, whether due to wind cranes now built the whole of the work, lifting all days, and the changes in the length of the boom pressure, or to the influence of the sun's rays, the material out of the barges in mid-channel, ends noted, and after everything was ready for provided for except the heavy floor girders, which weighed making the connection, the temperature yet failed (a) By the play left in the bedplates of the fixed nearly four tons each, and were hoisted by special for several days to rise to within 6 deg. to 8 deg. of cantilevers. tackle with wire ropes and steam winches set up the 60 deg. required, and the large bolt-holes were (6) By the arrangement in the keyplates between near the ends of the cantilevers. barely half open. The application of hydraulic lower and upper bedplates, which permit a slightly It was not long before the Jubilee cranes, which pressure only gave about in., equal to 3 deg. of circular movement on the centre of each column, had originally started from the tops of the Inch- temperature, and there was nothing for it but to producing torsion in the same. garvie tower, and had proceeded, the one towards wait patiently. At last, on the afternoon of Oc- from the (c) By the central vertical pins in the interlocking the south and the other towards the north, met tober 10, with the sun shining brightly f Trangement between ends of cantilevers and ends face to face, the two others, which had come down south-west, the temperature being 55 deg. gene- to of central girders. from the tops of the Queensferry and Fife towers rally, the west boom came together near enough All vertical deflections are taken with the in of the last a full bolt-hole but the east boom wanted a up and resisted respectively, and putting give ; by the elasticity of the metal in the structure. lengths of booms, their functions practically came quarter of an inch, in spite of all the pull that As soon as the end of of rams so a posts the cantilevers had to an end. (See Plate IV.) could be got out the hydraulic ; quan- been built, the necessary preparations were made to Much, however, remained yet to be done, for tity of waste soaked in naphtha was put into the start with the erection of the central girders. The the connections had to be made, and the making of bottom booms for about 60 ft. to either side of the at the principle upon which this work was to proceed was these depended largely upon the weather, or gap and set on fire, and in a few moments the same as in the cantilevers, by overhanging, but any rate upon the temperature. As it was not boom had expanded to the full amount required. in the absence of a fixed joint between the two, convenient to arrange the joints exactly in the All the bolts, twenty-three in number, were at hand- other arrangements had to be made. Botli ends centre of the girder, where they would have coin- once put into the holes and screwed down side of the central girders required to be temporarily cided with the junctions of the last pair of struts tight. The web-covers across the gap to each attached to the cantilevers until they were brought and ties, the joint was laid in each instance some of the booms, and the corner angles, were put on, together in the centre of the span, and could there 6 ft. nearer towards Fife and Queensferry. The and one side, which had been kept blind, was be joined up. The ends could then be released. four bays of the Inchgarvie halves were, therefore, drilled through at once, and the covers bolted up. This been made at t.he time of the movement ,7is the bolts at joint having felt, the central joints the least thickness was J in., in the flooring of the highest temperature of the day, when the canti- of these ties (see Fig. 130, at M) were gradually viaduct. levers and girders were of the greatest length withdrawn and the ties altogether detached. At The various hydraulic rivetting machines, by owing to expansion, it follows that as soon as tem- the same time the furnaces were set going, and which about one-half of the rivetting was done, perature decreased, the cantilevers and girders the plate-ties made so hot that, whether a rise have already been described in the places where would shorten, and the only gap left in the bottom or fall in temperature should take place, these they carried on their work, and need not be further booms, namely at the Inchgnrvie end, where the ties could no longer restrain any movement, but enlarged upon here. wedges were placed, would open. Had the change would yield to either influence. With the removal At the commencement, ordinary furnaces tired between the maximum temperature of day and the of these ties the central girder entered upon its full with coal were used for heating, but it soon became minimum temperature of night been considerable function as a connecting link between the two canti- evident that these could not be taken on the out- the wedges would thereby have been released, and, levers, and the south span was thereby successfully lying platforms owing to their weight, the weight, if free, would have dropped out. Precautions had, completed. A careful levelling on October 12 of fuel, and last, though not least, to the danger of however, been taken, and had the wedges been showed a camber of 3 in. in the girder, and no de- fire caused by hot ashes left on timber staging. ever so slack they could not have moved from their viation laterally from a straight line drawn between Various kinds of furnaces were designed and places. In addition to this, hydraulic cylinders had the centre of the ends of the two cantilevers. tried, all heated by oil, and in the end the difficulty been attached to the ends of the wedges, by means The north central girder had in the mean time was solved by turning the burner of an ordinary of which they could when necessary be drawn out been built out in a precisely similar manner, and by Lucigen lamp, in a somewhat modified form, into a from between the plates. The change was, how- October 15 it was sufficiently advanced to allow a small furnace and setting fire to it by a piece of ft. to laid across. in oil. tre- ever, only about 3 deg. , and with the tremendous gangway 05 long be This enabled burning waste drenched This was compression on these wedges could make but little the directors of the company to walk across the mendous advantage, for these little furnaces, though difference. bridge from end to end the chairman of the made of iron and brick-lined, weighed little more In this condition the girder was left overnight, company being actually the first person to cross than half a ton, and could be handled and shifted but carefully watched, and all changes of tempera- the north span. about with the greatest ease. All they required ture and of movement in the upper booms ascer- By October 28 the last booms were put in, and by was a small pipe-lead to supply compressed air, and tained and noted d wn. November 6 everything was ready to connect this a small tank with oil, and a crane would pick them At 6 A.M. on October 11 a start was made with girder also. The temperature on that day did not up and put them into any place where they were the drawing of the wedges first at the Queensferry rise, however, sufficiently high to make the joint, most handy. A boy could work them and turn out end, and then at the Inchgarvie end of the girder, but in the night a sudden rise took place, and by 200 rivets an hour easily, all heated evenly to a and they were drawn down with little effort. 7.30 in the morning the bottom booms were joined bright yellow heat in perfect condition for the (See Fig. 143 at C C.) At the same time the wedges together for good. hydraulic machines, three or four of which were or key-plates which closed the top booms were It now required a good fall of the temperature to fully kept going by one of these little furnaces. placed in position and driven down hard into their get the top booms connected, for the two halves of They were taken inside the tubes, and the smoke, places at A A. The top boom connections were this girder had been set less high at starting, and if care was taken in adjusting the burner, could somewhat different in their nature, the stresses, there was now practically no camber in the bottom not molest any one. after connection had been made, being exactly the booms. But the weather remained obstinate and Larger furnaces were set up in No. 2 shed for opposite of those in the bottom booms, namely, the temperature very high, and it was not until the heating angles and tees, and they were very suc- compressive instead of tensile. morning of November 14 that the key-plates could cessful owing to the regularity and evenness of the It will be remembered that the weights of the be driven in and the final connection made. An flame and the facility with which they could be two halves of the central girders were held up by episode, of which much has been made in the lighted and kept up. the four plate ties connecting them with the canti- papers, occurred on this occasion, and the facts are For the hand-rivetters in the struts and lattice- levers at D D, Fig. 143. The expansions in the simply as follows : After the wedges at the bottom girders, ordinary small forges were in use, with cantilevers, after the bottom booms were connected, ends had been drawn out and the key-plates driven bellows worked by a treadle or by the hand. But would have the effect of drawing up the centre in, a slight rise of temperature was indicated by the here also the oil-furnaces came in usefully, for not of in the furnace if portion of these booms in the same way, as if, thermometer in the course the morning, and only were the rivets pre-heated instead of a central girder, there had been a simple orders were given to remove the bolts in the central one happened to be anywhere near, but the boys rope attached to these ties. On both cantilevers joints of the connecting-ties and to light the fur- contrived to make a connection somewhere with contracting or shrinking, the rope would have been naces. Whether the thermometer indicated wrongly the compressed air pipes, and thus obtained a con- tightened and lost some of its downward deflection or whether the cantilevers had not had time to fully stant blast for their forges and saved themselves or sag at B. This was precisely what occurred to expand under the rise of temperature, or whether a the trouble of working the bellows. the bottom booms of the girder, for the top booms decrease of the same took place it is not now possible In places where so large an amount of timber were still gaping and could not prevent the further to prove, but when only about 36 of the turned staging was required, and where a fire on such opening of the gap. A temporary sliding connection steel bolts remained in the joints, and before the staging might have been accompanied by the most was, however, arranged in the top booms in such furnaces could get fairly started, the plate-ties disastrous results to portions of the permanent manner that nothing could prevent their moving sheared the remaining bolts and parted with a bang work, such furnaces as above described are of in- nearer together or further apart with the changes like a shot from a 38-ton gun. Something of a estimable value, for there is nothing left behind in temperature. (See Figs. 140, 141, and 142.) shake occurred in the cantilevers which was felt at that could cause a fire after the men left work. As The gaps left between the webs of the booms, the opposite ends, and caused some little commotion soon as the supply of air and oil are turned off all the which were here thickened to 2 in., were, as before among the men. No mishap occurred, however, flame at once disappears, and in five minutes stated, from about 10 in. at top down to 6 in. at and nothing in the way of a fall of the girders took inside is black and cold. bottom of the web. (See Fig. 143.) The gaps place as stated in the papers simply the work of The ordinary small furnaces used in the tubes and at A had been templated and the key or wedge - the furnaces and the task of knocking out 36 bolts on the staging were about 11 in. wide by 8 in. high plates made to these templates. It will now be was saved, and the girder swung in its rockers as and 4 ft. long on the inside, with two doors for understood that, in order that the bottom booms freely as if it had been freed in the most natural charging and drawing of rivets. They consumed of the girder should retain their camber or upward manner. about two gallons of oil per hour, with which they deflection, it was essential that these wedge- And thus the Forth Bridge was completed for could heat 200, and on an emergency 250 rivets per shaped spaces should be closed at the lowest the remaining work was simply to replace temporary hour, or even 300, if of smaller size. possible temperature, for, when once in their connections by permanent ones, to rivet up those The actual size of this kind of furnace is however and it is places, the top boom was closed like an arcli in which were only bolted, and do the thousand and a matter regulated entirely by circumstances, for their which the keystone had been placed. one things which always remain to be done after not possible to lay down hard and fast rules in Fortunately the setting up and holding up of everything is said to be finished. construction. The furnaces and fittings shown the girder halves during construction had given the The thrilling portion of the story is done, and the illustrations are : bottom boom as much camber as was required, and the novelist would wish to leave off with so dramatic A furnace for heating the ends of angle bars, tees, it needed no assistance from the drawing of the an incident as that just told. But there are yet or narrow plates. (See Figs. 144 to 146.) An to ties, otherwise some days of delay might have some details which belong to the history of the early form of oil furnace with grate at bottom occurred, for the temperature kept high and the bridge, and which could not very well be left keep a body of glowing coal to assist combustion. contraction in the cantilevers was not sufficient to unrecorded. This however is not necessary. (See Figs. 147 to furnace as used draw the ties much. RlVETTINO. 149. ) The latest form of small rivet The key-plates were then driven down hard and An early estimate has fixed the number of on the stagings and inside the tubular members. the heavy web-covers on each side were at once rivets in the Forth Bridge at 5,000,000, but this (See Figs. 150 to 152.) or drilled through and bolted up. At the same was evidently insufficient and the figure has risen Figs. 153 and 154 show the disintegrator, spray itself. In time T bars of heavy section were placed at the. to 6,500,000. It is, however, doubtful whether producer, the action of which explains top and bottom to form a temporary connection of even this covers the total amount, for on the its present form it is much simplified, and if any is the flange plates. Timber struts from side to side central or Inchgarvie pier, where an exact record obstruction in the small jet occurs, it easily to keep the booms apart, and wire rope ties to hold of rivetting was kept, the number closed there cleared by screwing back the mouthpiece. them together, were also put on. amounts to near upon 2,700,000 alone, and a very TEMPORARY WORK IN CONNECTION WITH The remaining halves of struts 4 and ties 4 of the large quantity of material was sent across from the THE ERECTION. Queensferry half of the central girder were also shops and the field which had already been rivetted that in templated now to the required size, and put in up, and such rivets are not included in the above If the proud boast is perfectly justified across the place as soon as possible. total. The rivets varied as to diameter from 1J in. building the two 1710 ft. spans Forth, steel massed The gaps in the top booms having now at the for the heavy tubes and the skewbacks down to and erecting the 11,600 tons of therein, stick of timber into lowest temperature been filled by the key-plates, the | in. for the buckle-plates; and, as to length, from without having placed a single that this mode effect of a rise in temperature and consequent 11^ in. (measured without the head) down to 1J in. the river, it is yet equally certain amount of expansion of the cantilevers would be to buckle The greatest thickness of plates rivetted together of erection entails an immense auxiliary which is both and waste- the temporary plate-ties between central girder and was 9 in., and this occurred in the top junctions at and temporary work, costly to time. There were cantilevers at D D, Fig. 143. As soon as this the head of the vertical columns on Inohgarvie ful with regard many days lost for or and weeks through waiting crossings money expended, but for the absolutely reliable I between the girders and the ropes, the former could junctions to be built up and completed, and although character of this article, and for its manifold uses, be raised and lowered at will and held in j position much of this may be said to be due to the novel In the first instance there were nearly a score of . until a joint with other portions of the work was character of the work, yet it is a point which must cages or hoists for the raising of men and materials made. Thus in the central towers, once they were not be lost sight of. Elsewhere, it has been stated to the different levels at which work was cirried on, completed, everything within the area could be that owing to the general batter of the sides of the and these were going continuously day and night suspended, and thus the internal viaduct was built and to all of its members out for several and there is not a case on the easiest manner in structure, owing being years, single [in possible, every length of the perpendicular, as well as the horizontal, they record of a rope having given way without having succession being held up until the girder was corn- had a natural tendency to either fall together, or given ample warning. At first the pulleys over plete and able to carry itself. And thus in the j else apart, and in both cases apt to be both out of which the ropes passed were rather small in diameter, ' same manner while building out the bottom the right direction. Thus in building out a pair of and the result of continuous running was that single members in cantilevers, the vertical ties and struts, : struts or ties, so soon as a length of 30 to 40 ft. had wires commenced to give way, but with a crackling and later on the wind bracings, a few wire roj es been built, it became necessary to put up temporary noise which soon became known to the attendant at attached to the upper members, as far back r.s girders to hold them apart or keep them together, and a large amount of dangerous work had to be done before a further section of work could be Fig 145 built. The members themselves, even when only bolted up, were often so stiff that hydraulic rams had to be used to force them apart or draw them together. In other cases wedges of hard wood and union screws were able to deal with them. In look- ing at the illustrations and plates showing various phases of the erection, this feature will immediately attract attention, and in many cases it must be difficult for any one except those conversant with the structure to distinguish between temporary and permanent work. For reasons explained above, and easily under- stood, it was not possible to fix the wind-bracing so close up to the new work that temporary appliances could be dispensed with, and therefore an immense number of lattice-girders, some heavy, some light, had to be used to allow the permanent members to be corrected, and when corrected held in position. In the bottom members, especially near the piers, where they were some 120 ft. apart, centre to centre, the temporary girders naturally had to be very strong and heavy, but after the completion of three bays, timbers were in most cases sufficiently strong to take all resistance, and this much simpli- fied matters, for timber is both light in weight and easy to cut and shape to requirements. Thus in the bottom members alone, at every vertical tie and at every junction, the necessary corrections required OIL FURNACES FOR HEATINf! ANGLE BARS. Disintegrator Fig OIL FURNACES FOR HEATINO RIVETS. of to obtain a fixed hold, held and if the placing of temporary struts and wire rope ties, the hoist. With the introduction of pulleys necessary up smaller drew the ends to any and in most cases when finally fixing the horizontal 3 ft. (5 in. in diameter, and guide pulleys not required up overhanging of desired wind-bracing girders, similar girders had to be placed than 18 in., and having the bottom the grooved position. lasted three It is to call attention to the weight to fix the position of the member. A repetition pulleys laid with hard wood, the ropes only necessary of these in with that of chain of this kind of work with every tie and strut, in to four times as long, that is from nine to twelve ropes comparison cables and of to see at bottom members and top members, at every vertical months. Even when taken oft' the hoists, moreover, hemp ropes equal strength, act as once the which the use of these tie, and at every intersection, made up an amount they were quite good enough to guide ropes great advantages offered for the kind of work which of work of which no visible trace is left, yet which to the cages, or to support steady weights when ropes particular had to be done at the was as real in its day as any which helped to build used as pennants, or as temporary ties between the bridge. up the mighty fabric. various members of the structure. All cranes used upon the erection had their Circum- THE USE OF WIRE ROPES. ference of chains taken off by degrees, and were supplied with Wire Hope. Of all appliances in use during the erection none wire ropes instead, which did the work more quietly have given more unmixed satisfaction than steel and with far more safety and reliability. Still more wire ropes. It may be considered a rash guess, useful were the ropes when portions of overhanging though the writer at any rate has no hesitation in girders or other members had to be temporarily making it, that the list of accidents would have been suspended from other portions already fixed. In doubled at least, and a great deal more time and these cases, by means of union screws attached fil ( ) Iii all cases mentioned here the wire rope had a I ing into the hollu-.v of the rail. The rails are them and away through them. The top members i down higher breaking stress than the other two. j screwed by |-in. wood screws with hexagon in central towers, all horizontal bracing girders, Facility of attachment was also a very g xwl fea- heads. The total weight of rails, fish-plates, bolts, and all recesses in top and bottom junctions, are like an for the double line of rails done in this ture ; for could be tied &c., they ordinary rope, expansion joints, j way. or else have the end fixed round a common thimble across the bridge and viaducts, is over 600 tons. The whole of the inside of the skewbacks, except or deadeye, and be used with shackles. Nearly -ill The rail-troughs are drained of water through where the nuts of the foundation-bolts are situated, the small stages which had been passed up and holes drilled into the sides every few feet at the are also dealt with in the same manner, and the down or along the members were hung by short level of the top of the tranverse blocking. In the same at the bottoms of the vertical columns, the pennants made of wire rope. floor of buckle-plates between the four troughs diagonal columns, and the struts in cantilevers; ' in Finally, they could bo slung alongside or across holes are placed to let the water through, these and all cases pipes are fixed to lead the water to the structure, and by means of running snatch- spaces being made up with asphalt mixture in such the outside. By this means it is hoped to prevent j blocks every place made accessible to the men, or manner as to lead all the water to the outlets. all rusting in the places where access for constant they could be used for raising material by means of Tho footpaths on each side of the double line are and thorough inspection, is not easily to be had. worked over a steam-winch barrel. made up like ordinary pavements, on the system single whips THE WORKMEN. The of wiro ropes for this purpose is followed by the Seyssel Asphalt Company, the employment ^ as a it well shown in the large illustration on Plate X. and slope being such as to lead all water to the outer Taking them whole, must be freely ac- Plate XV. sides. knowledged that the workmen employed upon the The sizes used here mainly were the 2J in. or EXPANSION JOINTS IN RAILS. bridge have not, to any material extent, added to the troubles and anxieties 5 in. diameter, the 2| in. or j in. diameter, and the These are all arranged on the same principle, attendant upon such a work. Black are 1J in. or f in. diameter were used on cranes or for though of different lengths. In the approach sheep found everywhere, and of the of such a single whips upon steam winches. For special viaduct span, and at the fixed ends of the central doings tolerably lively account might that a be of them of purposes 3j-in. and 4-in. ropes were used, and for girders, the movements are so insignificant easily presented. Many hundreds them birds of the service of men's cages and hoists the 3 in. or very short rail-joint suffices to regulate the lateral were mere passage, who arrived on latter a of the due to contraction the worked for a week or and 1 in. diameter. The tests for the gave displacement points ; but, tramp, two, passed on to other breaking stress of 26 tons to 28 tons, while nothing at the sliding ends of the central girders, where again parts, bringing a pair of hands heavier than 3 tons in the case of material and provision is made for a longitudinal movement of with them and taking them away again, and having in the 35 cwt. in the case of a cage full of men were ever two feet, and at the ends of the fixed cantilevers, mean time made extremely little use of them put upon them. where half that length is provided, the arrange- except for the purpose of lifting the Saturday pay ment is somewhat more complicated. Without packet and wiping their mouths at the pothouse; THE PERMANENT WAY. others going more into detail, it will suffice to say that many also, who, too clean-shaven and too the is absolute fixture to as to tried to deceive The internal viaduct has already been fully de- long rail-tongue made an closely-cropped hair, vainly to scribed in connection with the structure. The four the rail-trough in which its uncut end rests. Its any one as the character of the hotel they were last or in which the double line is laid are 18 in. pointed end, cut at an of 1 in 63, projects staying at, to invent a plausible account of rail-troughs | angle into the and rests on a fixed the which had left in depth by 16 in. in width. (Fig. 155.) They are opposite trough plate big job thty just completed. The which therein, laying up close to the backing rail, which paddle-steamer, carried the men across is bent away at an angle of 1 in 63 from the point the river morning and night, during the day made of the tongue. The outside of the flange of the hourly trips to the north shore and back for the ser- vice of the rail-tongue is cut in long steps at the same angle works and for the accommodation of of 1 in 63, and is held down by draw-washers to visitors. Before many months had gone by it waa known all over the to the plate, which forms one piece with the backing- country every tramp that a free rail, but in such manner that it can slide in and passage could be had for the stepping on board out with the expansion and contraction. In doing the boat, and the number of men who, when on tho south for a so, however, by means of the sloping steps it draws side, were invariably asking job on tho north the lower plata and with it the backing-rail always side, and vice vend, increased at such an close to the which thus retains its alarming rate that steps had to be taken to stop '-Teak bluckp every up joint, position .'Pine blocks befneen - relative to the centre line of the bridge and thus the nuisance. keeps the gauge correct. The contrivance is very But apart from these, it is no exaggeration to say that ingenious and unfailing in its action. (See Fig. 127.) no one need desire to have to do with a more The wind fence on each side of the viaduct is civil or well-behaved lot of men, always ready to to -it, -..< 4 ft. 6 in. high, and of close lattice work, and it is oblige, always ready go where they were told to crowned by a handsome teak handrail of sub- go, cheerfully obeying orders to change from one stantial appearance. place to another, and, above all things, ready txj help others in misfortune, not with advice but with PAINTING. hands and purses. Nor was there any difference in that on account of All plates, bars, angles, and other parts belong- respect nationality ; Scotch, ing to the superstructure, received as soon as they English, and Irish were about equally represented had passed through the shops or yards a thorough as to numbers, and though the latter furnished scraping with steel scrapers and steel wire brushes, very few skilled hands, they were mostly very hard and afterwards a coat of boiled linseed oil applied workers and very conscientious and reliable men. as hot as possible. As soon after erection upon the For the sinking of the caissons a number of struct ure as c< mid conveniently be done, and in many foreign workmen were employed for a short time, cases also before they were put up, they received and it is rather a curious coincidence that, as in to asphalted the bottom tho level of the heel in a coat of red lead paint, and subsequently a second foreign workmen did some of the earliest work in the in angle-bars, order to make a water-tight coat of red lead. The paint finally decided upon connection with the bridge, so now again a number bottom. Upon this bottom are laid transversely, for the bridge is an oxide of iron paint, of which of foreign men are employed upon some of the about 2 ft. every 8 in. apart, blocks of teak about two coats are applied over the two coats of red lead last work namely, the laying of the asphalt lave- 5 in. square. Between these blocks the spaces are already laid. The first is called a priming coat of ment along the footpaths of the permanent way, filled in with blocks of creosoted all set about chocolate brown the last is a coat which is done under a sub-contract the pine, dark ; finishing by Seyssel in. to J in. apart, and the whole is then filled up of a bright Indian or Persian red, which, however, Asphalt Company. to level with a mixture of pitch and tar and black darkens considerably in a short time. Four Several strikes occurred during the building of which sets oil, quickly hard. different kinds of paint are used, all, however, of the bridge, most of them brought about, not by the , Stiffening plates of steel, about 6 in. wide and the same composition, if of different makers. men themselves, but by organised committees in in. are ri vetted in jf thick, about every 14 ft., and At Fife : Craig and Rose's. connection with various Trades Unions and their about 2 in. above blocks. All project the teak At Inchgarvie : Galley's Torbay. disputes with employers in other parts of Scotland. blocks are cut with an inward slope towards the At Queensferry : Carson's. The causes were often trivial enough, such as the centre of each line of about in. to ^ the foot. For central girders : Wolston's Torbay. discharge from the works of some idle scamp with The whole mass of blocks and filling, which The above are for outside painting only, the rn inordinate allowance of tho gift of the gab, and seals the completely lower portion of the trough, inside of the tubular members receiving one coat whose demand to be reinstated in his dignity at are now dressed for the reception of the longi- of red and two coats of white lead paint. twenty-two shillings per week, caused an immense tudinal sleepers, which are about 12 in. by 5i in., It is calculated that inside and out, the amount amount of useless suffering to scores of his fellow- and also of teakwood. They are cut in lengths of surface to be painted is equal to 145 acres. workmen, and more still to their families, and a are of which multiples the 2 ft. 8 in. distance of proportionate increase in the takings of the neigh- the transverse ASPHALTING. blocks, and are notched where the bouring whisky shops. occur. to the extent of :) in. The batter to the sides of the structure The strike took in plate-stiffeners Play -, ff given principal place early June, to in. is J left between sleepers lengthwise. brings with it one disadvantage, namely, that one- 1887, and was brought about through an accident, the Through sleepers holes are bored every 2 ft. half of each lattice-girder flange forms with the caused entirely by the carelessness of a few men. or 3 and ft., f-in. pins driven down into the blocks vertical web a recess in which rain-water can lie A movable stage for rivetters, consisting of two The are in sleepers kept position transversely by and cause rusting. To prevent this, all places so girders about 110 ft. long, disposed on either sido wedge-shaped blocks of teakwood. The upper situated that the water cannot of its own accord of the vertical columns, was hung by wire roper faces of the are dressed to receive the drain are tilled with that from winches worked worm and worniwhee' " long sleepers away asphalt-concrete is, by rails of bridge" section, the heaviest yet rolled a mixture of asphalt, pitch, tar, and coarse gravel placed above. The stage served for rivetting tht 120 Ib. weighing to the lineal yard. A section of to such an extent that all water will run off by wind-bracings between the columns, and was made the rail is shown in Fig. 156. The rails are joined gravity. Where this is not possible, or would lead good by planking across the two girders in any a horizontal by fish-plate underlying the flanges, to too much weight being put on, holes are drilled, place required. When one section had been done into tho and sunk sleepers with a projection enter- and the asphalt so laid that the water is drained to the stage was raised to the next section, and while tliis was being clone one of the girders fouled a the men having died after admission), and 518 Railway at Dalmeny, the latter from the north piece of timber left in the girders. This was not minor accidents, which required, however, the arches of the bridge to a junction with the North noticed, and in spite of the resistance the men kept attendance of a medical man. British Railway at Inverkeithing. forcing at the handles of the winches until one of the Apart from the benefits of this Club, however, The engineers for the approach railways are wheels broke, and the whole stage rattled down, the men's welfare was looked after in every Messrs. Sir John Fowler and Baker, and the con- carrying with it some other staging on which some respect. While working in the foundations boots tractors Messrs. W. Arrol and Co. The further men were working. Two men and a boy were killed, and waterproofs were provided for them free of works are : and two more wounded, and before the real facts charge. Later on, during the erection, they were On the south side : were known the usual agitators quickly organised a given thick woollen jackets, as well as overalls and 1. A line from Dalmeny Junction in a more strike, demanding an increase of a penny per hour waterproof suits, and although a nominal charge direct line to a junction with the North British all round, equal to a rise of from 15 to 20 per cent, was made for some of these in order to check the Railway at Corstorphine Station, outside Edin- in their wages, on account of the dangerous nature carelessness and bad treatment of these things, it burgh. Total length, 6 miles. Engineer, Mr. of their work. As might have been expected the was rarely enforced against a careful and deserving James Carswell. Contractor, Mr. W. Arrol. principal spouters at the meetings held during the man. 2. A line from a point between Dalmeny Junction next following few days were men who worked in Large shelters and dining rooms were provided and the Forth Bridge, to a junction with the North the yards away from all danger, or who did not for them, with stoves and men in charge to heat British Railway at Winchburgh. Length, 4i miles. work at all, and after holding out for a week most their food for them, and these were not only on deck Engineer and contractor the same as for Corstor- of the strikers were glad to be allowed to come back. but on the top of the central towers, at the level of phine line. That accidents were frequent no one who can the viaduct and right out near the very ends of the On the north side : form an idea of the nature of the work upon such cantilevers. Here the men not only could take 3. A line from Inverkeithing to Burntisland to a structure need be told, but it is equally true that their meals in warmth and comfort, but they could join the ordinary route from Edinburgh to Dundee, fully three-fourths of all more serious accidents retire also in case of heavy showers or sudden rid Granton and Burntisland. Total length, 7 miles 3 were due entirely to what may strictly be called storms. chains. Engineer, Mr. W. R. Galbraith. Con- preventible causes. If any charge can be brought In cases of accidents not caused by the men's own tractors, Messrs. John Waddel and Sons. against the workmen, or at any rate a large propor- fault, the full wages were as a rule paid by the con- 4. Widening and doubling of a line from Inver- tion of their number, it is that of utter indifference tractors until the injured man was able to return to keithing to Townhill Junction, both on the North or carelessness with regard to danger of causing work, or unless an action was raised against the British system. Length, 5 miles 24 chains. Engi- injuries or death to one another. Not that in cases contractors. neer, Mr. James Carswell. Contractors, Messrs. of sudden accident men would have hesitated to Every care was also taken and no expense was G. and R. Cousin. risk limb or life for the sake of helping. On the spared to make good and secure staging for the 5. A new loop line from Cowdenbeath to Kelty, contrary, at such times the most heroic efforts were workmen, and to construct gangways and roomy both on the North British system. Length, 2 miles made to succour those in but in the staircases to all work was carried on. 69 chains. Mr. W. R. Galbraith. Con- need ; every-day places where Engineer, work with that fatal familiarity that is said to The wages paid to all classes of workmen were as tractors, Messrs. Charles Brand and Son. breed contempt while working on stages which a whole rather above the average, and as by far the 6. Widening and doubling of a line from Kelty could hardly be made large enough or strong enough greatest amount of outside work was done by the to Mawcarse, North British system. Length, 10 to hold the litter of tools and rubbish which they piece, a skilful and steady workman was enabled to miles 3 chains. Engineer, Mr. James Carswell. constantly gathered, they were throwing about make double and treble his ordinary time wages if Contractor, Mr. John Best. hammers^and drifts and chisels, and pieces of wood, he applied his abilities and energies in the right 7. A line from Mawcarse through Glen Farg, to a which in a moment were over the side, and tumbled direction. junction with the Bridge of Earn station, North British down upon may be three or four other tiers of stag- Some curious aspects of the labour question deve- system. Engineer, Mr. W. R. Galbraith. ing, where men were engaged upon their work. loped themselves in connection with piecework. Contractors, Messrs. Charles Brand and Son. Special gangs of men were organised to clear all The hand-rivetters worked invariably in squads of A glance at the map of Scotland will show that these things away, and endless warnings and four, namely, two rivetters, one holder-up, and one through these new lines the North British Railway entreaties were given, but to no avail, and it needed rivet-heater, generally a boy or lad. Now it is easy obtains access to both the east and west of the the sight of a wounded and mangled fellow-creature, to see that the skill or the want of it in the last northern parts. To Dundee and Aberdeen, via or his bloody corpse, to bring home to them the functionary was of great influence upon the number Inverkeithing, Burntisland and the Tay Bridge. To seriousness of the situation and the advisability of of rivets put in during a day's work, and con- Perth and the districts served by the Highland stooping to put down a tool instead of throwing it sequently a sharp handy lad was worth a good wage, Railway, via Inverkeithing, Kinross, Glen Farg, carelessly away. and as a rule he knew it. Rivetters are not and Bridge of Earn. The line from the Forth In the summer of 1883 a Sick and Accident generally very steady, but often lose a day or two, Bridge to Winchburgh opens a direct route to and Club was started upon the works. The member- in which case one or more of the squad are liable to from Glasgow and the west coast without touch- ship was compulsory for all employed by the con- enforced idleness. After some little discussion ing Edinburgh. The following is the estimated tractors, and the amount of contribution to the among themselves, these rivet-heating boys stood cost of connecting railways now under construction funds was one hour's pay per week, the maximum out for a fixed minimum sum, 20s. to 24s. per week, on the North British system : contribution 8d. week. Members were and this had to be whether the worked being per paid squad South of the Forth : entitled to medical advice and medicines, bandages, or not. This did not of course affect the employers, &c., for themselves, and medical advice for their for in piecework the head man of the squad was Dalmeny to Winchburg 56,000 wives and but no in so much 100 and he had to settle families, medicines, and, paid per rivets, ,, to Corstorphine 78,000 addition, if unable to work, an allowance from the with the other members of his squad. In another North of the Forth: funds to the sense it is said the is father to the here proportionate weekly contribution boy man; Inverkeithing to Burntisland ... 213,000 made. This aliment from 9s. to 12s. the was master of several ranged up boy men. The wages New lines, and widening and week. funerals of were per The members were also paid weekly. doubling existing lines within certain and in of paid limits, cases of death or The number men employed varied somewhat between Inverkeithing permanent disablement by accident or injury sus- with the nature of the work to be done, and and Mawcarse, also Glen tained on the works, grants were made to widows, naturally also with the seasons, as in some instances Farg line from Marcarse and children. it was wives, The contractors contributed next to impossible to work during the night. to Bridge of Earn 435,000 a sum of 20CW. yearly to the Club, and gave a good In the spring of 1887 the number had risen to 3200, deal of other substantial assistance. The Club and rose to over 4100 in of the same September Total estimated cost , 774, 000 a boon to the and still to After the to full proved great men, more year. lifting platforms were up The following Table of comparative distances their wives and children, inasmuch as they got a height in the central towers the number fell again between Edinburgh and four towns north of the deal more care and attention than the winter months to about but rose great they during 2900, Forth, both by Caledonian and North British, may otherwise would have been likely to experience. again as the summer advanced. The largest number be of interest: Special medical men were appointed at Dunferm- employed at one time was 4600. From January, line, North Queensferry, Leith, Edinburgh, Kirk- 1889, the numbers gradually decreased, and in liston, and South Queensferry. An ambulance January, 1890, the average was 1200, and in waggon was provided, and temporary hospitals February, 1000. A large proportion of these hands with every appliance needed in case of accident are platelayers working upon the permanent way, were established upon all three main centres. and painters and their labourers. The removal of The amount contributed by the members of the the staging round the piers and the landing jetties, Club in the year 1888, when the greatest number and the disposal of the plant, as well as the restora- was employed, was 4096L, which, with donations, tion of the ground occupied by the workshops the contributions by the firm, &c., came up to and yards, for agricultural purposes, will occupy a 4546!. Out of this sum sick allowances were paid goodly number of hands for some months to come out to the amount of 162H. accident ; allowances, yet. 729/. funeral ; expenses, 143L ; widows' allowances, THE RAILWAY CONNECTIONS. 176Z. ; donation to the 10CK. The Royal Infirmary, ; and railway works now in course of construction, the rest being medical fees and other expenses. and more or less directly connected with the Forth The attendances by the medical staff amounted to Bridge, are extensive and important as regards the over 26,000 in the year. On the average 99 men amount of heavy work they entail. Of these only were receiving aliment from the Club every week. two lines are being constructed by the Forth Bridge Of accidents between July, 1883, and Christmas, Railway Company, the remainder being done by the when the 188!), Club ceased to exist, there had North British Railway Company. The two lines occurred 57 fatal, 106 which required removal to are the south approach and the north approach rail- the infirmary in Edinburgh (in which number, ways, the former extending from the south arches howcvur, some of the fatal accidents are included, of the bridge to a junction with the North British is but the THE SOUTH APPROACH RAILWAY. quantity of spoil the east side of No. 2 cutting was expenditure year by year concerned, enlarged to the necessary extent. total amounts are correct and authentic. This line has a total of 58 chains, and length Geologists will have it that this is the site of an 20 ft. on the passes through a cutting about average extinct but it will be best to volcano, probably For half-year ending in soil and and strata of free- depth, through clay, leave this question to be settled by geologists. intermixed with coal and shale. stone, In the excavation of tunnels and cutting, pneu- At about 10 chains from the the new bridge matic drills were generally used with good results. the Forth Bridge Station is situated. At 45 chains The used were both and ordi- explosives dynamite HI December 31, 1882 7000 line to Winchburgh branches off to the west with nary blasting powder. June 30, 1883 42,800 a sharp curve. The total rock excavation amounted to 341,500 and December 31, 1883 57,000 The building of the Forth Bridge Station, cubic in the solid. yards June 30, 1884 119,000 the of cutting, bridges, and embankments in is as follows: widening The filling the banks December 31, 1884 218,200 not at first contemplated, will bring up the total Bank No. 1 cubic 33,400 yards. June 30, 1885 231,000 cost to about 20,0001. The contract will probably estimate No. 2 115,600 (original ) December 31, 1885 216,000 not be finished until the end of April. .5 69,000 (excess) 73 C ^ ^-" June 30, 1886 188,000 3 M No. 3 198,100 .2 December 31, 1886 253,500 THE NORTH APPROACH RAILWAY. ~-3 Masonry 24,850 1 June 1887 240,000 C H 30, This line is two miles in and com- Ballast 13,350 S 8 December 31, 1887 243,000 nearly length, -4J & O mences with an embankment at the north end of Filling 1,000 June 30, 1888 195,700 o o Aog /rom a flwtognijjh by the Lumtvn Stereoitfjjiic Cuinjn J. T. Leather, the well-known hydraulic engineer. who would have risen to eminence, had he been It was an awful load to put on the shoulders of i a able to husband his threw his life in man who had sufficient Here he had ample facilities for obtaining strength, away already to attend to in the schemes of the the thorough training in several branches of his calling, furthering promoters. When combating physical difficulties of the affair. and in all cases his experience was gained in works the autumn approached, and the fatal thirtieth o The troubles with vestries and their engineers and hove in ha< of very considerable magnitude. Yorkshire enjoys November sight, surveys and drawings officials, with owners of property and their agents, to at the were for the advantage of possessing a great number oi be made greatest possible speed. Th many years during the construction of the o first diverse industries, and it was very early in the field hours of the night were annexed sometimes all section of the Metropolitan Railway tedious as a manufacturing district. From its coal, iron, them to supplement those of the day, while mealf and wearying to the last degree. All these were had to be taken when or not at all line steel, and woollen trades, in addition to its farming they could, finally overcome, and the was opened. So far of the rest to the rank from there a and shipping pursuits, great wealth was rapidly The deposit plans brought being difficulty in inducing people to hac accumulated after the close of the bad times follow- and file, but the chief responsible engineer travel by it, the traffic astonished the most expe- to the still work lienced ing the Napoleonic wars. The entire world waf then enter upon more trying railway experts. The general public did then the customer of England, and the shrewd of preparing for, and attending, Parliamentar; not take the view laughingly expressed by Lord of the to secure a committees. Often he had to appear before Palmerston when asked by Mr. Fowler to people Ridings managed large " perform share of the trade. The thus was able to three or more committees in one day, pitting the opening ceremony, I intend to abov county " keep find employment for many engineers, and among his wits against those of half a dozen counsel ground as long as I can. Of course they grumblec eminent Th< at the them .Mr. Leather took a leading position. He backed by opposing engineers. ventilation, or rather the want of it, and re executed many works for the supply of water, engineer could not imitate the members of the bar proached the engineers for not improving it. Origi- notably those of Sheffield. The Stockton and and choose in what cases he would appear ant nally, when a junction with other railways was not Darlington line was opened when Mr. Fowler which he would neglect, taking his fees for all intended, a special hot-water engine without a live was only eight years of age, and the Liverpool and Indeed, it is said that Charles Austin, the leader o fire, and therefore not passing the products of com- Manchester Railway when he was but thirteen. the bar in the committees of the House of Commons bustion into the air of the tunnel, was proposed. He had not completed his pupilage before the rush, had once been engaged to appear before twenty-twc Experiments were made with an engine so con- which eventuated in the railway mania, commenced. committees in one day, and as it was impossible for structed, but before it was perfected it was decided When Mr. Fowler left Mr. Leather he went him to attend to them all, he showed his impar to make a junction with the Great Western Rail- straight into the railway world, finding in the office tiality by reading his newspaper and attending to way, and, therefore, locomotives of ordinary con- of Mr. J. U. Rastrick a very wide field. He be- none. The progress of committee work was watchec struction had to be admitted on the system. came his chief assistant in the preparation of the with keenest interest by men who did not know It was in 1853 that the first Act was obtained for and contracts for several an embankment from a but who took ad a line miles in from to drawings railways ; among cutting, 2J length Edgware-road these was the lino from London to Brighton. To vantage of every turn of the fight to manipulate tin Battle Bridge, King's Cross. Plans for extensions this latter Mr. Fowler gave great attention, and share market. They listened to the evidence o: westward to Paddington, and eastward to the City, there is scarcely a bridge or viaduct which was not the engineer and sold and bought accordingly. I: were at once prepared, and the financial support of personally worked out by him. After two years spent he tripped in his advocacy of a measure, or was the Great Western Railway was secured. After a in London, he returned to Mr. Leather, and became foiled in his attack on a hostile scheme, they hurriec severe fight, the Act for the extended railway was responsible resident engineer of the Stockton and to anticipate the effect on the money market. Mr. obtained, the plans providing for tunnels and Hartlepool Railway. After it was completed he Fowler once met an acquaintance rushing along the stations large enough to accommodate the broad remained two years as engineer, general manager, corridor of the House in the wildest excitement, gauge Great Western trains, as well as the narrow and locomotive superintendent of that and the and when he stopped him to learn the cause, the gauge local trains which it was designed to run. Clarence Railway. It is no wonder that these en- man exclaimed, "Don't detain me! Roberl There was, however, a difficulty in raising the gineers of tha old school can turn from one subject Stephenson has broken down in his attack, and 1 capital, and it was not till the spring of 1860 that to another with so much versatility when we con- am off to buy a thousand Great Northerns." Every- the contract was made, and the works commenced. sider what an education they had. Instead of body gambled in shares, and like all gamblers their In 1861 powers were obtained for extending the to fill them with choice was determined the merest trifles. If a to and having professors ready digested by Metropolitan Railway Moorgate-street ; knowledge, like the young men of the present day, line were fortunate, promoters would endeavour to in 1864, for constructing the eastern and western they were moved from one position of responsi- appropriate as much of its name as they could for extensions to Tower Hill and Brompton respec- bility to another, and their intellects were hardened other linea, in the hope that their particular venture tively. In 1863 a Lords' Committee decided that and invigorated by constant work. Every step they would gain by the association. As an instance Mr. it would be desirable to complete an inner circuit took was Sn experiment on a working scale, and Fowler's Great Grimsby Railway was at a premium, of railway that should abut upon, if it did not every fact they learned was imprinted on their and consequently the name of Great Grimsby waf actually join, nearly all the principal termini in memories by the toil and trouble it had cost. brought in quite irrespective of geographical facts. the metropolis, commencing with the extension in On 'the termination of this Mr. This was done to such an extent that the then chair- an and direction of the Metro- engagement, " easterly southerly Fowler visited, at the invitation of Sir John Mac- man of committee (Lord Devon) exclaimed What ! politan Railway, from Finsbury Circus at the one neil, several railways in the neighbourhood of Great Grimsby again ! Go it, Great Grimsby !" end, and in a westerly and southerly direction from Glasgow, and gave evidence before Parliamentary Mr. Fowler had now attained a position which Paddington at the other, and connecting the ex- committees regarding them. He commenced an necessitated his permanent residence in the metro- tremities of those lines by a line on the north sicle independent career at the age of twenty-six, and as polis, and work of all kinds flowed in to him. It of the Thames. The inner circle was the direct we have already seen, he started with a broad and is quite beyond the limits of our space to notice, outcome of this recommendation. solid foundation of experience, suitable for the much less to describe, one-half of the matters The construction of the so-called Underground towering reputation which was to be built upon it. about which he was consulted or the works he Railway was the means of solving a great many Several important railways were then being pro- carrjed out. Amongst them we may mention the problems which at the time presented much diffi- moted from Sheffield, such as the Sheffield and Lin- following : The Oxford, Worcester, and the Wol- culty. Questions which are now fully understood, the Great the New ; the Severn and which would be undertaken contractors as colnshire, Grimsby, Holland, verhampton Railways Valley Railway ; by the East Lincolnshire, and others, and of these Mr. the London, Tilbury, and Southend Railway (in a mere matter of course, then were of very grave Fowler became the chief engineer, conducting them conjunction with Mr. Bidder); the Liverpool Central importance, and had not only to bo exhaustively through Parliament and carrying them out. It was Station, the Northern and Western Railway of Ire- discussed, but to be attacked with the greatest in the year 1843 that this work was commenced, land, the railways of New South Wales and India, caution. It was not then known what precautions and before it was completed the railway mania the Sheffield and Glasgow Water Works, the were necessary to insure the safety of valuable attained its full The of that Inner Circle the St. John's near to the excavations how to timber proportions. history Metropolitan Railway, buildings ; movement has often been written how fortunes Wood the ; Railway, Hammersmith Railway, the cuttings securely and keep them clear of water were made and ruined in a how men lost their and Midland the Victoria without the day ; Highgate Railway, Bridge drawing sand from under the founda- reason in a moment both from and evil and Pimlico the and tions of to good Railway, Glasgow Union City adjoining houses ; how undermine walls, tidings, and how the capital subscribed during Railway, and St. Enoch's Station, the Millwall and, if necessary, to carry the railway under houses those years, often for the wildest undertakings, Docks, the Channel Ferry, and many others. and within a few inches of the kitchen floors with- almost rivalled the of the South Sea Bubble. Mr. Fowler's with the out down how to days reputation general public pulling anything ; drive tunnels; We have no intention of redrawing the picture, of this generation rests to a great degree on his con- to divert sewers over and under the railway, to the but following incident will show at what high struction of the Metropolitan Railways. These were keep up the numerous gas and water mains, and to pressure engineers were expected to work in those so far out of the common that every Londoner, and maintain the road traffic when the railway was One when Mr. Fowler was in a out of took the carried on underneath days. night asleep great many people London, greatest being ; and finally, how to his father's a and four house, carriage drove up to interest in them. The most extravagant anticipations construct the covered way so that buildings of any the door, and the household was aroused by loud were indulged in as to the relief they would afford height and weight might be erected over the rail- knocking. On descending Mr. Fowler found that ;o the streets if they were ever completed. But way without risk of subsequent injury from settle- a prominent promoter of railways had called with the difficulties were so enormous that many, if ment or vibration. All these points Mr. Benjamin the of him to purpose inducing undertake the engi- not most, people imagined that they could not Baker declared, in a paper read some five years ago of a from neering new railway Leeds to Glasgow, be overcome. The directors were constantly Dcfore the Institution of Civil Engineers, received and that as an earnest he had brought an order for being told that they had embarked their own much anxious discussion and criticism before they as a 20,0001., preliminary payment on account of money and that of the shareholders in an impos- were decided upon. Such questions as the admis- the survey expenses. It then only wanted a very sible enterprise. Engineers of eminence assured sible stre.ss on brick arches loaded on one haunch few weeks for the (quite inadequate purpose) :hem that they could never make the railway, that only, the extent to which expansion and contrac- before the of the Mr. Fowler if made it could not work if day depositing plans. they they it, and they ion of iron girders would affect buildings carried by had the to decline the and the car- worked it would it. prudence offer, nobody travel by Such a -hem, the ability of made ground to resist the of the riage disappointed promoter went thundering catalogue of impossibilities was enough to appal ateral thrust of arches, and a multitude of similar the little how and often faith in the fell to away, occupant dreaming many years any man, enterprise a >robiems, had to be dealt with tentatively at first, would before his would be carried .ow such times elapse plan out. ebb. At they would say to Mr. ind with increased boldness as experience was of iron " It was only men constitution that came un- Fowler, We depend upon you, and as long as ;ained. As an instance of the confidence which scathed those times, and an tell us have confidence we shall on." through many engineer you you go experience gives we may cite the following : doubts E entertained by the engineers as to the behaviour of be as extensive as possible, and should em- whole duties of the engineer were not comprised a compound brick and iron structure led. to a timber brace every branch of professional practice. The n the mere accomplishing of the objects entertained front being put to the Edgware-road Station, where sound knowledge and experience thus acquired by his employers. It was his duty, he held, to 49-ft. in it rested on a span girder ; yet 18(i5, when would add greatly to his efficiency and value advise those who consulted him whether the under- the extension to Moorgate was executed, no hesita- in any special branch. For the railway engi- aking was one that would repay the expenditure tion was felt in trusting an elaborate brick and neer there was required a thorough knowledge which must be made upon it. The engineer was ashlar face wall, weighing 1300 tons, to a continuous of surveying and earthworks, the capacity to not merely a man of technical skill engaged to girder 135 ft. in length. design bridges, earthworks, and tunnels, and Dridge the difficulties of capitalists, as a servant to a of effect the orders of his the It would be tedious and unprofitable attempt knowledge the of floods and drainage. carries out master ; on con- to give a detailed account of the construction of To this should be added some knowledge of archi- .rary, he was a member of an honourable and noble the Inner Circle line, since the lessons taught by it tecture, and a taste for appropriate decoration. profession which could not lend itself to enter- have long ago been incorporated into the routine of The dock and harbour engineer required, he said, prises which did not give fair promise of being engineering practice. It will ever remain a monu- much of the general knowledge of the railway Deneficial to the world, and to the advancement of ment to the skill of the engineers concerned in its engineer, with a vast amount of special know- civilisation. construction. Of these Mr. Fowler is responsible ledge. This included the laws which govern the In 1870 Mr. Fowler took part in a commission for the greater part, as shown by the annexed tide, the set and speed of currents, their scour sent to Norway to examine the railways there. which the and due and also to the trade to As is well known has built a of Table, gives lengths percentages silting ; questions relating Norway great length to each. be accommodated, and the methods of dealing with railway which was constructed at a very small cost Inner Circle Railway. the goods. He would also be required to be cog- and is worked very cheaply. Now, at the date men- Length p nisant of such matters as harbours of refuge, piers, ;ioned the Indian government were undecided landing stages, lighthouses, forts, and hydraulic whether to adhere to the broad gauge of 5 ft. 6 in., appliances. The water works engineer, in addition which had been adopted for the trunk lines, or to Mr. John Fowler, engineer 11 20 to his general qualifications, had to be familiar with introduce a narrower gauge for the less important Mr. Edward Wilson, 27 the means of information about A commission of General Mr. Francis Brady, 28 collecting rainfall, railways. composed Mr. Joseph Tomlinson, Jun. 35 the method of gauging streams, the excavation of Strachey, Colonel Dickens, Mr. Rendel (now Messrs. Hawkshaw and Barry 58 reservoirs, conduits, weirs, tunnels, and aqueducts. Sir A. Meadows Rendel), and Mr. Fowler, was, He must also be competent to superintend and therefore, sent to Norway, for the purpose of 13 8 100 design sewerage works. The mechanical engineer, acquiring information as to what gauge should be The main lines of the Metropolitan and Metro- the speaker continued, dealt with the most varied adopted in India, assuming that it was decided that politan District Railways being complete, Mr. and numerous subjects of all the branches of engi- a narrow gauge should in certain cases be laid Fowler carried out the lines in connection with them, neering. He must understand the laws of motion, down. The commission was received and accom- the St. John's Wood of of and he be familiar Mr. Carl the including Railway, the heat, liquids, gases ; must panied by Pihil, experienced engineer Hammersmith line, the West Brompton line, and with the strength of materials and the friction of of the Government, who had carried out all the others. His original plan, brought before the surfaces. On railways he was responsible for the railways in Norway. They travelled over the Parliamentary Committee, included an outer circle machine tools, engines, and locomotives. For Dovre Fjld by carriole, passing over the ground as well as an inner circle. Unfortunately, the docks he had to design the machinery for working on which a railway has since been constructed, Committee was induced to reject the outer circle the gates, the sluices, and the cranes. For water and were thus able to see the nature of the on the faith of certain promises made by another works he produced the pumping engines, sluices, works which would have to be carried out. The line. These promises have not been practically valves, stop-cocks, &c. And so on through the Norwegian lines are 3 ft. 6 in. gauge, and the rails fulfilled, and the immense advantage of being able entire series of works in which mechanism is em- and engines are both very light, the speed being to conduct all through passenger, goods and ployed. The mining engineer needed, in addition usually quite slow. Mr. Fowler considered this mineral traffic by a perfect and comprehensive to a knowledge of railway and mechanical engineer- gauge narrow enough, and the engines too light for for scheme around London was lost ever. ing, the information requisite for sinking shafts, economy. His colleagues, however, took a different Although somewhat out of chronological order, we draining workings, excavating and raising minerals, view, and recommended 2 ft. 9 in. as the proper may here refer to another underground railway, and preparing them for market. gauge for India. of which Mr. J. H. Greathead is the engineer. Mr. Fowler then turned to the preparation Two reports, therefore, were made, one by This railway the City and Southwark Subway required by a civil engineer to enable him to Mr. Fowler recommending 3 ft. 6 in. gauge, and is at of it is not opened the time writing, but perform his work efficiently. This he classed one by the other members of the commission, recom- 2 ft. 9 in. final decision of rapidly approaching completion, and great hopes under four heads : (1) General instruction, or a mending The Govern- are entertained that it will be the of a new liberal education as a ment was between the but much nearer Mr. pioneer ; (2) special education pre- two, of which will as a for technical technical Fowler's viz. a or 3 ft. in. system railways prove great paration knowledge ; (3) opinion, metre, 3^ convenience as those in existence in the for It was understood that the referred to already knowledge ; (4) preparation conducting prac- question metropolis. The ventilation difficulty is avoided tical works. He supposed a boy to start at four- the Commissioners was not whether narrow-gauge entirely by the device of using electric power for teen years of age with a strong constitution, con- railways should be adopted in India or not, but, the propulsion of trains, while the expensive work siderable energy and perseverance, and a fair supposing a narrow gauge to be adopted, what gauge of diverting sewers and pipes, underpinning build- education, together with a mechanical bias. The should it be. Mr. Fowler, from his long experience ings, disappropriating tenants, and buying property, period from fourteen to eighteen should be of the evil on the Great Western Railway, had very is evaded by keeping the tunnels at a very low devoted, he said, to a special education, including strong objections to breaks of gauge except when level. As the line follows, for the most part, the mathematics, natural philosophy, surveying, draw- unavoidable. He would never permit an exceptional streets, there is little to pay for land, and the ing, chemistry, mineralogy, geology, strength of gauge in a link, or a possible link line, nor for chief expense is that of construction. A Bill now materials, mechanical motions, and the principles short branches where exceptional plant would before Parliament contemplates the creation of a of hydraulics. To these must be added considerable neutralise all saving. He considered that an ex- second railway of this kind from Bayswater to progress in French and German, even at the sacri- ceptional gauge should be confined to a district of King William-street, B.C., Sir John Fowler, Mr. fice of classical studies and pure mathematics. At country where break of gauge is unimportant by B. Baker, and Mr. J. H. Greathead being the the age of eighteen, assuming the boy to have fair reason of non-interchange of traffic, and even then engineers. If it is made it will prove the greatest abilities and more than average perseverance, three he preferred to adopt a light railway on the standard advantage to Londoners. courses were open. He might be placed with a gauge, except under very peculiar circumstances, the Mr. Fowler was elected President of the Insti- civil engineer for four or five years' pupilage, or in which must be very rare indeed, when narrow tution of Civil Engineers for the year 1866, and a mechanical workshop, or he might be sent to one gauge would have some special advantages. took the chair for the first time in that capacity on of the universities. The choice would depend on Last winter (1888-89) Sir John Fowler had the January 9. His presidential address was devoted the taste of the boy, the means of his parents, and opportunity of verifying by actual inspection on to rail- to the subject of the education of an engineer, and other circumstances. If he followed either of the the spot, the opinion he had formed as the Vas so important and valuable that it has been first two courses it would be necessary for him to con- way policy of India, and it is well known that he reprinted and distributed extensively, notably by tinue his studies in mathematics, science, and foreign has expressed himself as having had his former the Government of India to the engineers in its languages at the same time. If the latter course conclusions strongly confirmed by his Indian visit. employment. He began by calling attention to were adopted, the drudgery of learning to survey, Sir John visited Darjeeling to see the work- the fact that the exclusive position hitherto held to draw, and the like, must be passed through first. ing of the 2 ft. 6 in. gauge mountain railway, by the English engineers was not likely to continue, With a clever hard-working boy the most advan- ascending 8000 ft. by gradients of 1 in 27. This since both in France and Germany great efforts tageous course might be to send him, from seventeen curious little railway has been laid on the fine were being made to educate young men both theo- to eighteen, into a good workshop, then for three road made to Darjeeling, and, being saved all ex- it is not retically and practically for this profession. Hence, years for a university course, and finally into an penses except that of permanent way, although this was greatly to the advantage of engi- engineer's office for his pupilage. This, of course, surprising that a good dividend is earned, notwith- draw neering science, it behoved the Institution to see would require a bty of special ability and determi- standing the fact that the engines can only that the distinguished and leading position which nation to render it a successful course. The office less than twice their own weight up the incline. In had been so well maintained by their great prede- chosen for the pupilage to be passed in ought to be this case the gauge and everything else are suited should not be lowered those who came not the to the but unless the same circumstances cessors, by well organised and too large ; engineer traffic, after them. After a short enumeration of the should be a comparatively young and rising man, were found the system could not be applied else- nature of the works and duties which fell to the and be accustomed to take pupils, who should be where with advantage. lot of a civil engineer, he proceeded to enforce the few in number, and bear some proportion to the Sir John was naturally much consulted, both necessity of a full comprehension of the nature number and extent of the works in usual course of professionally and otherwise, in India by the and qualites of materials, and the proper adapta- construction under the engineer's direction. Here authorities on the subject of railways, docks, and tion of the design to the materials in which it was the pupil ceased to be a boy, and his future success water works, and was received everywhere with to be carried out. He asserted his conviction that or failure could no longer be directed by others, great distinction. His general impressions of India it was most important that the early preparation but depended upon his own abilities and industry. and its resources were of the most favourable and subsequent study of an engineer should Mr. Fowler also laid stress on the fact that the character. in Mr. and 150 miles One of the most interesting chapters menced, constructed, it was never The line was one of easy construction, with no Fowler's career is that connected with He carried or recent would have works of , Egypt. out, Egyptian history magnitude except the Nile crossing. When first in search of been while thousands of went there, in the instance, greatly changed, British practicable it kept to the villages and cultivated health the connection thus soldiers and millions of would have been lands on the ; and accidentally money banks, but sometimes it took an in- . Ismail Pacha remained in saved. land formed lasted as long as course amongst the mountains to avoid expen- power. As is well known, that enterprising Mr. Fowler, before deciding between the two sive works, and sometimes it traverued deserts to Sovereign threw himself heart and soul into the possible routes by the Nile Valley and by Souakim- cut off bends of the river. The gauge was fixed at of the had had interviews with General 3 ft. 6 the material improvement country. He Berber, long Gordon, in., same as the Norwegian railways, but unlimited credit in the markets of western and also with the and other with a heavier rail of 50 Ib. to the money governors persons yard ; the maxi- Europe, and he aimed at restoring Egypt to its acquainted with the country to be traversed. The mum gradient was 1 in 50, and the minimum radius the of ancient position as one of the chief producing Nile Valley was ultimately chosen, and decision curvature 500 ft. The cost, including stations, ratified his ministers. countries of the world. He brought about a wide by the Khedive and The sidings, quays or landing places, rolling stock, work- extension of the irrigating system of the Delta, in surveys were commenced at once, and when com- shops, and all expenses required to complete the order that crops might follow each other inde- pleted the Khedive, with characteristic promptitude, line ready for traffic, was estimated at four millions pendently of the season of the year; he introduced instructed Mr. Fowler to obtain a contract for the sterling, or 7240J. a mile. Of this amount five- sugar plantations and factories in Upper Egypt on a work. This was accordingly done, and on February eighths would have been spent abroad and three- most extensive scale; he built several railways, and 11, 1875, the works were commenced at Wady Haifa eighths in Egypt. projected one southwards to Khartoum, which, if with great ceremony in the presence of Mr. Fowler, It will be noticed that the railway was to start at completed, would have been the key to Central the governor of the province, the Cadi, and other the second cataract, some 550 miles, as the crow Africa. He entered upon every scheme with the notables, bullocks being slaughtered as part of the flies, from Cairo. The Nile forms a natural road- greatest ardour, and no sooner were the plans com- religious observances. The abandonment of the way between the two for the entire distance, except pleted than he urged the giving out of the contracts railway, and all the disasters which followed it for some throe miles at Assouan, where the first and the commencement of the work. In Mr. Fowler were keenly felt by Mr. Fowler, who fully believed cataract occurs. To enable steamers and dahabeahs the Khedive found the very man he wanted one that had Khartoum been thus connected with to pass from the lower to the upper level of this Cairo whose ability was only equalled by his rectitude. the turbulent native tribes could have been cataract, Mr. Fowler conceived the idea of a ship National is not to be founded and a would have been and in with Sir William prosperity, however, overawed, great economy ] incline, company (now docks and canals alone. Its basis lies effected in the run. it is not and Mr. Rendel he to by railways, long Unfortunately i Lord) Armstrong went in the ust administration of to to read the the site. good government and j given man future, and when matters The necessary surveys, examinations, wise laws but it is not our business to into the went in the of the estimates ; go wrong Egypt expense railway and were made, and on the return to politics of Egypt further than to explain the seemed too great for the resources of the country Cairo Sir W. Armstrong offered to undertake the condition of affairs when Mr. Fowler came in Although this railway was not completed, and work, and his proposals were approved. But like contact with them. has passed for the moment out of public notice, many other projects of that time in Egypt, the plan He landed in Egypt at the close of 1868. At this yet it is a matter of certainty that, sooner or was frustrated by the interference of jealous foreign time the Suez Canal was within a year of its com- later it will be constructed. The eyes of nearly rivals, and nothing was done. pletion, and it was natural that Mr. Fowler should all European nations are concentrated on Africa, The plan contemplated the construction on the to hurry see it, even before fulfilling the avowed and many are striving to secure a firmer foot- right bank of the canal of a ship railway 3 kilo- object of his visit of exploring the antiquities of hold on the continent with a view to gaining a metres in length, commencing at the bottom of the the country. The trip was made under very favour- share of the future trade which is anticipated. It cataract in the river channel, about 5 kilometres able circumstances, the party including M. de is certain that when Egypt attains the position south of Assouan, and terminating at the top of the Lesseps, M. Yoisin, the Duke of Sutherland, Sir which is sure to follow upon a few years of good cataract in the harbour of Shellal. The boats to be Richard Owen, General Marshall, the Marquis of government, there will be a revival of the old ambi- transferred were to be floated upon a cradle con- Stafford, Mr. W. H. Russell, and others. The works tions, and she will turn her attention southward, structed to run upon the railway, and to be hauled from Ismailia to Port Said, and the harbour works with that craving for extended sovereignty which over land by hydraulic engines of 400 horse-power, at Port Said, were well advanced, but between is the characteristic of all healthy communities. It placed near the centre of the railway. The water Ismailia and Suez nearly one-third, or twenty- will, therefore, be interesting to give a few facts to work the engines was to be pumped at a high five million cubic yards of excavation, remained regarding the route, length, and cost of the line pressure by a pair of large stream wheels carried to be executed. The survey occupied three days, which must be made if the flood of Arab invasion is upon pontoons, and driven by one of the smaller and included the whole length of the canal, to be permanently dammed. Sir John Fowler always rapids at the lower end of the cataract. The total everything being explained by M. de Lesseps with held the opinion that our difficulties in the Soudan length to be traversed over land by the boats was the greatest kindness, and the various points being came from the undecided attitude we took up. The 2950 metres at low Nile, and 2300 metres at ! high discussed without reserve. At the of the tribes Nile. of cost of incline request native could not be neutral ; they were The estimate the the with I editor of the Times Mr. Fowler addressed a long obliged to side either with the English or the machinery, workshops, wharves, and all expenses I to full letter that journal giving a account of the Mahdi. But the former declared that they had required to complete it ready for traffic, was state of the works and the of not to came to rescue criticising prospects come stay ; they Gordon, 200,0001 the company. This letter appeared on February 18, and when that was done they would retire, and One of the first matters claiming Mr. Fowler's 1869, and was made the text of a leading article leave the entire population "to stew in their own attention on undertaking the duties of consulting which pronounced it to be a fair and final summary juice." This promised to be so highly flavoured engineer was the organisation of the existing rail- of the subject by an English engineer of the highest with Mahometan vengeance that the tribes were ways, and to this he devoted much time on his first eminence and repute. obliged to cast in their lot with the successor of the official visit in 1871. As a preliminary he employed In the spring of 1869 the Prince and Princess Prophet, and fight against the invaders. In the Mr. D. K. Clark to obtain for him full details of of Wales visited Egypt. When about to make days of Ismail Pacha the Soudan was ruled by the the rolling stock and plant. With this information the journey up the Nile the Prince invited Mr. shadow of the authority which existed at Cairo, before him, Mr. Fowler was able to advise great Fowler and Professor Owen to join the party, and Sir John Fowler holds that the same conditions changes in the direction of simplicity and economy, which was embarked on five steamers and daha- would recur if the railway were completed. most of which were carried out. beahs. Nothing could be pleasanter than to make The southern terminus of the line was to be at The management had previously been of a the excursion under such conditions, as every ar- Metammeh, on the left bank of the Nile, imme- most unsatisfactory condition. In the year 1869 for the to rangement was made Royal party see the diately opposite Shendy, 16 deg. 14 min. N. lati- the expenses per train mile amounted to 7s., of of in the objects interest country, both ancient and tude, and 32 deg. 25 min. E. longitude. Shendy which the locomotive power figured for 3s. 5d. modern. Of course Mr. Fowler had to pay the is equidistant between Berber and Khartoum, and Many other items were needlessly high, and were usual penalty of fame, and to be prepared to suggest about 99^ miles from each. It is moreover the con- increased by the practice of keeping duplicate sets the probabls methods employed by the Egyptians verging locality for the camel routes from Khartoum of accounts, more or less imperfect, in French and in stones for raising large the pyramids and temples, and the White Nile district, from Hamdal, Souakim, Arabic. Mr. Fowler considered that the expenses and in cutting and polishing the greenstone and and the Red Sea, and from Aboo Kharraz and the could be well cut down to 4s. 6d. per mile, or diorite statues. At Thebes his engineering re- Blue Nile. There is good navigation between 36 per cent, of the earnings. This small percentage sources tried were severely by the Prince's cross- Berber and Khartoum for ten months in the year, was due to the very high traffic charges, particularly examination as to the manner in which the and the obstructions which exist in the low-water on the transit railway which conveyed the P. and O. colossal statue of Rameses 888 difficult to across the isthmus on this II., weighing tons, channel would not be remove or lessen. Company's passengers ; was brought from the quarry near Assouan to its The northern or Egyptian end of the lino was fixed line first-class passengers were charged 4|d. per at Memnonium on the of at at cataract. and second-class accelerated were present position plain Wady Haifa, the second Com- mile, 2|d. ; goods Thebes. excursion to The proved be most enjoyable. mencing at the foot of the cataract on the right charged 4|d. per ton, and unaccelerated Id. per Fowler returned Before Mr. home he had bank of the river, the line followed the general ton per mile. with the several interviews Khedive, explaining to course of the stream as far as Kobe, this side being In the same year visits were made to Upper him his views concerning the Suez Canal, the irri- chosen to avoid the drift sand from the Nubian Egypt to examine irrigation works and sluices, and gation schemes, and many other matters in which desert. At Kobe the line crossed the Nile, and to Suez to determine matters connected with the interested. of Ismail Pacha was The outcome this then followed the right bank as far as Dabbe. Here docks there. M. Duport, on Mr. Fowler's recom- was that he accepted the position of consulting the Nile makes a long detour, and consequently the mendation, was appointed engineer in charge of to the and the filled in engineer Khedive Egyptian Govern- projected line struck across the Bahiuda desert to the new Alexandra Docks, a post which he ment, a post which he held for eight years that its terminus. a highly satisfactory manner till the completion of until the abdication of that ruler. The office the is, The following are the lengths : workr. involved yearly journeys to Egypt, the first being In the following year, 1872, the most important in the latter part of 1871, and required Mr. Fowler Miles. matter for consideration was the sugar plantations Haifa to Kohe 160 to personally investigate all the great Wady and factories of the Khedive. several undertakings Koh^ to Ambukol 216 Already then in hand. The most important matter presented millions sterling had been spent upon them with Ambukol to Shendy . . . 176 to him for solution was the projected Soudan Rail- but poor returns, and the time had come when way. It is needless to say that, although com- 552 some alteration in working must be decided upon. in his Mr. Fowler at time of has which at the ,A> aid him forming judgment, irrigated any the year without pumping ; been associated, and one present secured the valuable assistance of Mr. (now Sir (2) to devise an improved means of introducing moment is engaging the attention both of the Frederick) Bramwell and Dr. Letheby. The flood water several times during high Nile upon any general public and of engineering experts in all result was that reports of the most exhaustive required lands on the left bank of the Nile, and of dis- parts of the world. Sir John lays no claim to be tlio character were presented to the Khedive, and formed chargingitat pleasure without interference with other sole author of the design which was the joint outcome for all future The lands to a for the construction of four all bent on the best and a valuable guide operators. ; (3) prepare scheme minds, discovering Khedive, however, was too sanguine, and the of a ship canal between Alexandria and Cairo. Mr. cheapest means for carrying a railway over the works were established too rapidly and on too Fowler proposed as alternative projects under the Firth of Forth. Most people will remember that a the climate was also first head a level canal on the bank of when the v/as extensive scale. Possibly ; (1) high right Tay Bridge destroyed, preparations suitable for cultivation. The broad the Nile a level canal on the left bank of were and not quite sugar ; (2) high being made, were actually commenced. serious loss of .j the the canal the of the for the Forth. Sir had result was a very money ; (3) completion present barrage bridging Thomas Bouch Government. or the construction of a new one. None of these designed a suspension bridge for the purpose, and During the course of the investigation into the proposals were then carried out, but during the past an Act of Parliament had been obtained authorising conditions of the sugar estates, several interesting few years, under the superintendence of Colonel Sir its construction. The failure at the Tay at once facts, worthy of being placed on permanent record, Scott Moncrieff, the barrage has been repaired to threw doubts upon the safety of the most ambitious were demonstrated. It was found that the soil ot such an extent that it will hold the water up to project, and the works were stopped. Subsequent Egypt, which, of course, is entirely Nile deposit, 3 metres, instead of 4. 5 metres, as contemplated by investigation showed that the proposed bridge consists of a large amount of fine sand, mixed with Mr. Fowler. The methods employed in the repair could not have been a satisfactory one. an unctuous clay, in the form of minutely divided of the barrage followed the lines laid down by Mr. A bridge across the Forth offered so much double silicates of alumina and iron, together with Fowler, but were on a less extensive scale, as the advantage to the railway companies forming the fine oxides of iron, alumina, potash, alkaline sili- pressure to be resisted was less, and there was east coast route to Scotland that, after two years, cates, soluble silica, and a fair proportion of car- greater difficulty in obtaining money than during the idea was revived. On February 18, 1881, the bonates of lime and magnesia. The soil is in Ismail Pacha's time. The deficiency of head is four great railway companies concerned, the such a minute state of subdivision that it readily made good by pumping into the higher canals. Great Northern, the North-Eastern, the Midland, yields its most important constituents (silica, The second undertaking required a canal starting and the North British, wrote to their consulting phosphoric acid, and potash) to the growing crops. very high up the Nile, and following the course of engineers Mr. T. Harrison, Mr. W. H. Barlow, For the cultivation of sugar it is necessary to the Bahr Yousuf, but it presented no features of and Mr. John Fowler, associated with Mr. B. equalise the excess of potash by the applica- special engineering interest, and was not attempted. Baker propounding two questions for thuir tion to the land of more phosphoric acid, and The third, the ship canal, was a subject in which joint opinions. They were asked to consider to make up for the deficiency of nitrogen by the Ismail Pacha took the greatest interest. He found the feasibility of building a bridge for railway addition of ammonia. Analyses were also made on that the effect of the Suez Canal was to divert the purposes across the Forth, and, assuming the another occasion of the Nile water to determine traffic from the capital, and to take the stream of feasibility to be proved, what description of bridge whether it had, when used for irrigation purposes, passengers through the country without adding any- would be most desirable to adopt. The matter any manurial value beyond that due to the sus- thing to its wealth or importance. He, therefore, involved so large an expenditure and contained so pended mud. The samples were taken about the conceived the idea of making Cairo into a sea- many novel issues that it needed to be approached middle of the months of June, July, August, Sep- port, with easy access to the Mediterranean. with the greatest possible care. It was fairly well tember, and October. It was found that in each Mr. Fowler worked out a combined irrigation and known how many types of bridge there were to case the water contained a considerable quantity of ship canal from the Mediterranean to the Bed Sea, select from for such a site; these were (1) Mr. nitrogenous matter in the form of actual ammonia, by way of Cairo. This canal would have been a Bouch's original design; (2) a stiffened suspension as well as ammonia derivable from organic matter. formidable rival to the Suez Canal, in so much as the bridge; (3) a second form of stiffened suspension of was dues derivable from the water would have a of The proportion actual ammonia largest irrigation bridge ; (4) cantilever bridge. Calculations in July and smallest in August. The organic enabled the tolls on ships to have been reduced to weight and cost were made for each type of bridge ammonia was smallest in the August sample a very low figure. In the negotiations which sub- and were discussed by Messrs. Harrison, Barlow, and largest in September. Taking the whole sequently took place with the Suez Canal Company, Fowler, and Baker, with the general result that the of the ammonia derivable from 100,000 parts of the possibility of the second canal being made, served cantilever type was chosen. A report was made to water, the quantity ranged from .0114 parts in the as a powerful lever in the hands of the English the railway companies on May 4, 1881, embodying August sample to .0271 in the sample collected in party. the result of the deliberations, and pointing out that June. These are remarkably large proportions Although so many of Mr. Fowler's Egyptian the cantilever principle offered a cheaper and better when we consider that the Nile does not receive schemes were not carried out, we must not regard solution of the problem than any other. The report anything in the nature of sewage or ordinary town them as wasted effort. For thousands of years did not enter into the details of construction; drainage, for they are largely in excess of the pro- Egypt has been the prey of conquerors of many indeed it could not be said to give even the broad portions found in the River Thames at Hampton. races and creeds. Probably for the first time in features, other than those which are involved in the The properties of soluble saline matters in the Nile her history she is in the hands of a power which use of the cantilever. These still remained to be water range from 13.443 parts per 100,000 in Oc- has no selfish aims, and thinks solely of the good of elaborated in council, and it was only by united tober to 18.8 parts in June. The chief ingredients the inhabitants. Under such conditions she must discussion that the original plan developed into the in these saline matters are the carbonates and sul- prosper, and the time is certain to come when many final design. Although the type of the bridge is phates of lime and magnesia, but there is also a of the ambitious schemes of her late ruler will very ancient there were many features in it which notable quantity of soda and potassa, as well as a become possible of realisation. At that moment were open to consideration, and to differences of trace of phosphoric acid. The sedimentary matters the reports and drawings of Mr. Fowler will be opinion, and at each meeting of the engineers new in the several samples taken amounted to 6.915 turned to as the key of the plans to be adopted. ideas were propounded, and novel methods of over- parts per 100,000 of water in June, and to 149.157 Space does not permit us to particularise all the coming difficulties were mooted. After most elabo- in the of in with which rate calculations the structure parts August ; and proportions organic great works Egypt Mr. Fowlerwascon- investigations and matter in the deposit ranged from .829 parts to cerned, such as the construction of steamers for the gradually, by a process of evolution or development, 18.414 parts. The results show that the water of Khedive, surveys for a railway to Harrar, and many assumed its present form. the Nile is remarkably rich in fertilising matters, others. For nine years he made periodical visits to The design being settled and the execution for not only does the water contain in solution a the country, and became greatly interested in its decided upon by the associated railway companies, notable quantity of ammonia, nitrogenous organic fortunes. The connection was broken, however, the carrying out of the work was entrusted to Mr. matter, and the soluble silicates of potassa and when Ismail Pacha was made to abdicate, and a Fowler, in conjunction with his partner, Mr. Ben- soda, as well as a trace of phosphoric and nitric new era of economy was introduced. Egyptian jamin Baker. acids, but it also contains in suspension a large credit was almost exhausted, and what little was The Parliamentary fight had been exceedingly amount of sedimentary matters which are charged left was destroyed by the revolt of Arabi Pacha. stubborn, for great interests were at stake. Hitherto with phosphates and alkaline silicates. A few years later (1885) the Queen, on the recom- the London and North-Western and the Caledonian The most important Egyptian question submitted mendation of the Marquis of Salisbury, created Mr. companies have enjoyed a great advantage in to Mr. Fowler was that of irrigation. Upon this Fowler Knight Commander of the Order of St. carrying the Scotch traffic to Perth and the High- depends to a great extent the fertility of Lower Michael and St. George "for important services lands, in consequence of the east coast traffic having Egypt, for although the annual inundations can be and guidance to Her Majesty's Government in con- to traverse the circuit from Edinburgh via Larbert depended upon to give the land one thorough water- nection with Egypt." and Stirling to Perth. But when the bridge is ing, there are many crops that need to be watered A curious example of the way that the engineer opened this advantage will disappear. A very several times and at different seasons of the year may be useful in averting political troubles is found strong hybrid semi-public committee was appointed, from that at which the flood comes. Immense in one of the incidents of Mr. Fowler's career. The with Lord Stanley, of Preston, the present Governor irrigation works were constructed by Mehemet Ali, Italian premier, M. Minghetti, had disagreed with of Canada, as the chairman. Engineering evi- with canals running through the delta and the land Garibaldi on the question of the rectification of the dence was brought forward to condemn the struc- on either side of it. For a considerable part of the Tiber. The popular patriot was powerful at the ture, and every possible description of hostile year these canals served their purpose fairly well, time in Italy, and wielded an influence which the evidence for shipping interests was adduced against but at the period of low Nile many of them became Government did not care to have exercised against it, and made the most of by eminent counsel, useless because they were at too high a level. This themselves. At the same time they did not feel able who both in speeches and cross-examination strove does not arise from any error of the designers, but to accept his views on the particular question before to the utmost to prejudice the undertaking. from the fact that the barrage, which was built to them. Mr. Fowler was at that time at Cairo on But at the close of the case the committee were maintain a minimum depth of water in the river, one of his Egyptian visits, and it was decided to unanimous in favour of the Bill, only stipulat- did not prove capable of resisting the required submit the matter to him. He was accordingly ing that the Board of Trade should maintain a head Hence it was necessary to allow the river to summoned to Rome, and was fortunately able to general inspection of the works during construction. fall below the proposed level. Under these con- reconcile the differences of the two parties, to the It was finally arranged at the suggestion of Mr. ditions Mr. Fowler was instructed (1) to prepare great relief of the Government. Fowler that the inspectors she .Id report to Parlia- alternative plans for placing all the cultivated and We now come to the Forth Bridge, the best ment every three months as to the progress of the cultivable lands of Lower in a to be known of all the works with Egypt position 1 which Sir John Fowler bridge, and the quality of the materialsand workman- PLATE IJ. From a pfiatoyrajth by liaaano. These made General Hutchinson if father had not laboured I should not be Lord to the consideration of the of thfr ship. reports, by my " entirely question and Major Marindin, have appeared regularly in our Brassey . In his many public utterances on the sub- best design, and the probable cost of Messrs. columns, and all have spoken in the highest praise ject of the Forth Bridge Mr. Baker hat always Schneider and Hersent's bold project. Whilst on of the way in which the undertaking was being brought this fact prominently before his audience, the subject of bridges it may be interesting to carried out. Speaking at Southampton seven years ago, he said: recall Mr. Baker's statement at the Institution of Sir John Fowler and Mr. Baker have kept a "The merit of the design, if any, will be found, Civil Engineers, that it had fallen to his lot to in personal and continuous control over the entireopera- not the novelty of the principles underlying it, repair and strengthen the three great historical tion of and have but in the resolute of well-tested of their first Telford building the bridge, superintended application bridges President, ; namely, the series of processes, from the rolling of the plates mechanical laws and experimental results to the the Menai Suspension Bridge, the Buildwas cast- to the closing of the rivets. They have further somewhat difficult problem offered by the construc- iron arched bridge, and the Over masonry arch employed several distinct staffs of assistants for tion of so large a bridge across so exposed an bridge across the Severn near Gloucester, and that authorities the purposes of (1) surveying and foundation estuary as the Firth of Forth." At Montreal, two he had succeeded in restraining the local work for for when the works were in full he from two of them or ; (2) working drawings ; (3) inspecting years later, swing, pulling down, doing anything ' " at the mills for the said : If I were to that the and which would affect the of these works plates ; (4) inspecting rivetting; pretend designing appearance and (5) for the fitting and erecting. Mr. Alan building of the Forth Bridge was not a source of as left by his great predecessor Telford. Stewart was chief of the staff in Westminster, present and future anxiety to all concerned, no Although in connection with the subject of the where all the detailed drawings and calculations engineer of experience would believe me. Where Forth Bridge it is fit that we should refer at some were made. The resident engineer was Mr. Cooper, no precedent exists the successful engineer is he little length to Mr. Baker's connection with bridge who entered Mr. Fowler's office in and has who makes the fewest mistakes." At Newcastle, the of the Institution of 1863, engineering, Proceedings" remained there ever since. Mr. Tuit, Mr. Lilliquist, last year, when delivering the workmen's lecture Civil Engineers, the Encyclopaedia Britannica," and Mr. Carey, and other engineers of exceptional of the British Association to an audience of 4000 and many other publications, and our own columns, interested ability were also on the engineers' staff. The con- men, he remarked that the success of the work was bear witness that he is no less profes- tractors were selected on account of their previous due as much to the individual and collective pluck sionally in tunnelling, ship railways, or other classes experience. Mr. Phillips had had great experience and ingenuity of the workmen as to the scientific of work offering the fascination of novelty and diffi- in Sir and Mr. labours ,nd of the and con- Mr. Baker holds an official under the bridge building ; Thomas Tancred organisation engineers culty. position the of tractors and as President of the Mechanical War as a civil member of the Ordnance Falkiner in large contracts and organisation ; Department labour Arrol shown on Science Section of the Association at he to whom all the ; and Mr. had previous Aberdeen, Committee, questions affecting also occasions remarkable ability and resources. In said: "I have no doubt that as able and enter- design of guns are referred. He has advised the early days Mr. Phillips took an active part, prising engineers existed prior to the age of steam the Metropolitan Board of Works during the past but in the preparation and erection of the steel and steel as exist now, and their work was as twelve years, and many other public bodies, on Mr. Arrol took the leading position, and he was beneficial to mankind, though different in direc- important engineering works of a varied character ably seconded by Mr. Biggart, Mr. Moir, Mr. tion." It is quite clear, therefore, that Mr. Baker projected or undertaken by them. Westhofen, Mr. Harris, Mr. Scott, Mr. Bakewell, does not labour under the common illusion that a Mr. Baker is a Member of Council of the Insti- be the tution of Civil of the of Arts ; and others. very great undertaking must necessarily Engineers ; Society this series of sketches of inci- work of men he told the of the British Association for the Advancement of Having brought very great ; and, indeed, to the Mechanical at that he would Science and also Past-President of the Mechanical dents in the career of Sir John Fowler up Engineers Edinburgh ; commencement of the Forth Bridge, we do not pro- be sorry not to believe that there were plenty of Science Section of the latter Association. He is of of pose to carry it further. In the columns of this engineers and contractors in England, Europe, and an Honorary Member the Society Engineers ; issue will be found full details of the design and America capable of building a Forth Bridge, if of the American Society of Mechanical Engineers, called to so in his if and of other scientific and bodies ; and a construction of that magnificent work. The bridge, upon do ; and that, opinion, literary however, has not monopolised the whole of Sir the engineers and contractors of the Forth Bridge Lieutenant-Colonel in the Engineer and Railway has deserved the which had been so Volunteer Staff John Fowler's time and attention ; he been praise liberally Corps. connected with many other important works in the awarded them, it could only be on the grounds meantime, besides fulfilling his standing engage- that they had done their work as well, probably, as SIR THOMAS TANCRED. ments. Sir John became consulting engineer, on any one else would have done it. Sir Thomas Telby Tancred, the eighth baronet of the death of Mr. Brunei, to the Great Western Sir John Fowler's professional training began his line, was brought up in the office of the well- Railway, and besides this and many smaller under- with level and theodolite in the north of England, known engineer, the late George Willoughby after takings, he is consulting engineer to the Great and Mr. Baker'? with hammer and chisel in one Hemans. He left England in 1865, shortly Northern, the Brighton, and Highland railways. of the oldest ironworks in South Wales. After the term of his pupilage had expired, and obtained the usual preliminary training of an engineering a position in the Public Works Department of New MR. BENJAMIN BAKER. student, Mr. Baker was articled to Mr. H. H. Price, Zealand. After a time he abandoned the profession he The career of Sir John Fowler, which we civil engineer, in whose workshops and draw- in favour of sheep farming, in which pursuit have endeavoured to sketch in the foregoing ing - office he acquired practical experience in distinguished himself, becoming a famous breeder, different exhibitions. columns, may be regarded as a contribution to the foundry, forge, and manufacturing processes, and and receiving many medals at early history of the profession rather than as a the designing of machinery and ironwork of all In 1876 Sir Thomas Tancred returned to England, biographical notice. When Mr. Baker began his kinds. At the works referred to were made, a and became associated with Mr. Falkiner as con- career, Sir John Fowler had been actively en- hundred years ago, Trevithick's first Cornish sulting engineer for the New Zealand Government, the title of gaged in a variety of important work for more pumping engines; and long before the eve of the the business being carried on under and than twenty years. The great pioneers of the pro- Liverpool and Manchester Railway, strange loco- Messrs. Hemans, Falkiner, and Tancred, fession had, most of them, either passed away, motives, with spur gearing and racks, and others under that of Falkiner and Tancred, as con- or had retired from active service, their work with double bogies, some of which have been tractxxs for public works. The partnership was dis- carried having been continued by those who had served illustrated by us, were turned out of the works, solved in 1886, and afterwards Sir Thomas com- with them, benefiting by their experience, and together with marine engines and steamboats of the out large contracts in Asia Minor, besides a that was enlarging it with their own. Engineering had, in earliest type. The portfolios of working drawings pleting the Delagoa Bay railways, work fact, been reduced to a science that replaced the thus embodied the whole history of the develop- very rapidly executed under his own supervision. a more or less experimental pursuit which had occu- ment of the steam engine in its application to rail- He is at present engaged in constructing railway over the the previous generation, and the foundation ways, navigation, mining, smelting and rolling across the Isthmus of Tehuantepec, nearly Eiedad been securely laid for the development which metals, and to other purposes. After three years same route as that located by the late Captain S'T to-day distinguishes the profession throughout the practical work at this branch of engineering, James B. Eads for his proposed ship railway. world. But it was not alone the early engineers Mr. Baker then underwent a further period of Thomas Tancred became an associate member of in and like who bequeathed a rich inheritance of experience to training elsewhere in surveying, levelling, and the the Institution of Civil Engineers 1868, their successors. Industry and applied science in designing of works in masonry and brickwork. Mr. Falkiner has practised as an engineer, besides every direction which could be useful to constructive Shortly after his arrival in London, Mr. Baker en- having been a contractor on a large scale for public work were progressing steadily and with rapidity. tered Sir John Fowler's office, and then gradually works. Especially this was the case with the manufacture took a more and more active part ia the many of iron, which rendered undertakings easy that important engineering works then being carried MR. WILLIAM ARROL. would have been impossible to the older engineers, out and proposed, including amongst others the Mr. William Arrol, like many other famous con- who had little at their disposal except timber, stone, Metropolitan Railway, and other railways in and tractors, is essentially a self-made man, who has and brick. And later, when, in the march of pro- around London. risen from the humblest position occupied by a gress, iron had to give way to steel, engineers were Mr. Baker was at that time a constant contri- worker in iron, to that of one of the principal con- enabled to undertake and carry out successfully, butor to the columns of ENGINEERING, and his tractors in the United Kingdom. Mr. Arrol, " undertakings which their immediate predecessors articles on Long-Span Bridges," first published who was born at Paisley, was apprenticed to a local could not consider for of the at the of thirteen he learned his seriously want proper by us, twenty-three years ago, were soon after blacksmith age ; ho materials. republished in America, Germany, Austria, and trade for four years, and it need not be said that a In the atmosphere of enthusiasm that naturally Holland. From these early days to the pre- learned it well. By the time he became journey- surrounds the successful completion of so vast a sent time, Mr. Baker has been associated, in one man, a financial crisis paralysed Scotland, and work structure as the Forth Bridge, one is too apt to capacity or another, with important bridges too being difficult to obtain, he went to England, followed his forget, in presence of the stupendous work, how numerous to mention in different parts of the where, for a considerable time, he much is due to the great army of workers who world; the latest and biggest of which, the Channel trade, and acquired a varied stock of knowledge have laboured blindly in some cases since the Bridge, Mr. Baker, as stated at the Society of Arts, that was to serve him well at a later period. to aid beginning of the century, and to ascribe some of undertook to investigate as an interesting scientific Always learning, and always saving money, career of the credit to its creators which is really due to problem, out of consideration to the high position of him in commencing the independent the main the general advance in mechanical science charac- its promoters and designers, Messrs. Schneider and which he had already laid down outlines, better returned t*i teristic of the age. As Lord Brassey said on a Hersent, and not as a promoter of the project him- Mr. Arrol when times grew in various recent public occasion, "I like to remember that self in any sense of the word, but confining himself Scotland, and found employment capa- the 1882 and In the mean time Sir cities, for all of which he was thoroughly fitted, by years 1887. John Ireland, are the Dungarvon and Lismore Railway; the decided that could virtue of his energy, industry, and versatile talent. Fowler and Mr. Baker had they Killorglin Railway and water works for Waterford, as a a or a the most of the work of Wexford and the Rathmines Whether working blacksmith, fitter, safely place important part ; and Rathgon town- the Forth contract in Mr. Arrol's and boilermaker, his work was well done, and was Bridge hands, ships, Dublin. Although in important practice as a always characterised by the touch of originality it is needless to say that Mr. Arrol has justified the contractor, Mr. Falkiner has never abandoned his which distinguishes the man born to command from confidence which the engineers placed in him. connection as a civil engineer, and has been associated one made only to obey. To do everything he in that capacity with several works of considerable undertook well, to forsake the grooves prescribed MR. TRAVERS FALKINER. importance. by established handicraft, for new and bolder ways, Mr. Travers H. Falkiner is a member of a well- MR. JOSEPH PHILLIPS. and never to avoid a menial task that might accom- known family long since settled in Ireland, of which The foui-tli member of the firm of contractors for ... his Richard of pany the undertakinguv.^nB in... hand,-, was..-. characteristic~ brother Falkiner, Mount Falcon, the Forth Bridge, Mr. Joseph Phillips, commenced to of his is the head he has been a his of Mr. Arrol. Speaking recently some County Tipperary, ; professional career in 1844, as a pupil to Messrs. j friends who presented him with a mark of their member of the Institution of Civil Engineers since Grissell, of London, and after serving his time he 1863. Sir Thomas he was a of esteem, he said : "Whatever I went to I put my Like Tailored, pupil entered the service of Messrs. Fox, Henderson whole mind to. Sometimes I was sent to clean the the late George Willoughby Hemans, and until the and Co., who were then building the Exhibition of flues instead of repairing the 1851. When the firm erected boilers, but I never shirked the Crystal Palace at Syden- the duty." It is in this that ham, Mr. Phillips acted as lies one of the chief causes of one of their outdoor " super- his success, that he never intendents, and he afterwards shirked his duty." It was was in charge of the con- inevitable that Mr. Arrol struction and erection of rise rise should and quickly ; Newark Dyke Bridge, on the before long he changed from Great Northern Railway, the the man-of-all-work to the largest ever constructed on foreman of the bridge and the Warren truss principle. boiler departments, in the His next work was the Bir- works of Messrs. Laidlaw mingham Railway Station and Sons, of Glasgow and roof, which is of 212-ft. span, Edinburgh. Here he remained and at that time was by far for some years, gaining the the largest roof in existence. experience which was neces- Since then Mr. Phillips has sary for his coming advance- frequently been consulted by ment. Twenty years ago the engineers on the subject of time arrived when he con- large-span roofs, and has sidered himself justified in carried many into execution. making his first and inde- While still in the employ- pendent venture, and he ment of Messrs. Fox and boldly launched himself as a Henderson he paid much contractor and repairing en- attention to the system of gineer, with the munificent sinking caissons by com- capital of 85Z. the savings pressed air, invented by Mr. ofhislife. Success wascertain, Hughes, and first adopted though Mr. Arrol did not know in constructing the founda- tions of it, because he had the good the Rochester Bridge fortune to possess the ele- by Messrs. Fox, Henderson, ments that, when combined, and Co. command success. It is in- Mr. Phillips joined the teresting to know that twenty firm of Messrs. Cochrane and years ago he purchased his Co., of Dudley, in 1856, as first engine for 181., his first their manager, and he sub- boiler for 251., and the few sequently undertook for them tools he could afford, and the erection of such well- which we may be sure he known structures as West- knew how to select to the best minster Bridge, and the advantage, and how to turn Charing Cross and Cannon- to the best account. How street railway bridges over many times during the last the Thames. He was also few years must Mr. Arrol associated with the same firm have recalled this, his first in the construction of the poor but all-important ven- bridge across the Mersey at ture, as he walked through Runcorn. Further recogni- the enormous shops and tion of his ability came with works he laid down to carry the adoption of his patent out the Forth Bridge con- for wrought - iron caisson tract. For two years after cofferdams, put down . by he started in business for open sinking or by com- himself, Mr. Arrol's life was pressed air, for the most that which has been led by difficult parts of the Thames thousands of other men under Embankment, and, by the From a pJiotopraph by John Feryut, Larffl. a Government, at the similarcircumstances, period MR. WILLIAM AEROL. Spithead of hope and disappointment, forts. Later on he was of waiting made tolerable only associated with the late Mr. bypatience anddetermination T. Parry i.i the contract for to succeed. In his case, how- the Central Railway Station ever, success came early, and and line at Liverpool, and within three years he had the Whitehaven Docks. Ho himself the advanced so far in means and reputation, that he was death of that well-known engineer, was closely asso- afterwards carried out by contracts for intrusted with the contract for iron bridges on the ciated with him in professional work, as assistant, the Campos Bridge over the River Para, for the and of with Brazilian Government the extension of the Glasgow, Hamilton, Bothwell Railway, one representative, and finally as partner, together ; Derbj thembeing a very large structure spanning the Clyde. Sir Thomas Tancred, in conjunction with whom he Water Works(under Mr. Hawkesley), and the Great Then followed the erection of another important acted as consulting engineer to the New Zealand Western Dock at Plymouth, for the Great Western bridge over the Clyde adjoining the Glasgow Central Government. In 1876 this connection was extended Railway Company. The foregoing are only some Station of the Caledonian Railway, and it was by Mr. Falkiner and Sir Thomas Tancred becoming of the works upon which Mr. Phillips has been for this work that Mr. Arrol devised a number contractors on a large scale, and together they engaged, but, of course, he has besides undertaken skill and were of special machines for drilling and rivetting executed many important works, including railways, many others, for which much ability up work, which, with necessary modifications, were harbours, piers, water works, sewage works, and necessary so largely used on the Forth Bridge. The Forth arterial drainage. Previous to his taking up a part Mr. Phillips' career has been all the more re- Bridge Company in 1873 entered into a contract of the Forth Bridge contract, he had carried out markable because he was removed from active life with Messrs. W. Arrol and Co. for carrying out for Sir John Fowler and Mr. Baker, the Limerick for a long while by a very serious illness, at a time Sir Thomas Bouch's design, and when the scheme and Kerry Railway, the Tralee and Ferrit Railway when he was busily engaged upon important was abandoned, after the failure of the Tay Bridge, and harbour, and the Didcot, Newbury, and South- matters, and which, after his recovery, left him in the reconstruction of this work came into Mr. ampton Railway, works amounting to 1,500,0002. a much less advantageous position for progress Arrol's hands, and was carried out by him between Amongst other undertakings completed by him in than he had formerly occupied. Since the starting of the Forth seven he has resided the remainder of the work but it is certain that it Bridge years ago ; and the regulation of the Danube at Vienna. For on the Mr. was interested was a wise decision to spot. Phillips specially entrust this part of the a time he was a partner of Sir Thomas Tancred, in the of the foundations of the main to some sinking deep undertaking one who had achieved a high and so became familiar with English methods of and in the execution of which the contractort in the piers, reputation specially difficult work of sinking carrying out work, while at the same time he grew wit?, the eminent French conractors foundations to a co-operated large considerable depth, by to be favourably and widely known by English M. Coiseau. The difficulties of that of the means of air. ' part compressed On the Continent works engineers. It was during this period that he con- will be realised what we have of this kind had been carried out on a undertaking by much larger structed a railway in Asia Minor. At the present said. Since the foundations were com- and under difficulties than in this already scale, greater time M. Coiseau is engaged in completing a large Mr. has been and in pleted, Phillips actively engaged country, no firm the world has earned so contract for the improvement in the port of Bilbao, with Mr. Arrol in the erection of a superintending high reputation in this field as MM. Hersent and on extensive railway undertakings in South the superstructure. Couvreux. At the time about 1880 when these America, and on other important works. There is contractors were carrying out the Antwerp Harbour no occasion for us to enlarge here on the manner MONSIEUR L. COISEAU. works, at a cost of more than a million and a half in which he carried out the sub-contract for the sterling, their engineer-in-chief, M. L. Coiseau, sinking of the Forth Bridge caissons, as the It would of too much o had be, course, say that the the responsibility of the foundations, a work details have been given on a previous page, but foundations for the of the Forth l piers Bridge could similar in many respects to those of the Forth we may add that many important appliances used not have been so successfully carried out by English Bridge. Before this M. Coiseau had been for pneumatic foundations have been designed by workmen and the firm of contractors who executed engaged on heavy contracts upon the Suez Canal M. Coiseau. APPENDIX. INSPECTION AND TESTING OF THE FORTH BRIDGE BY THE BOARD OF TRADE. SOUTH pUEBNSFERTtr PIER rsasT POSITION - 896 5," r -.- '^rrr >\: i.- ,."--,,. .-;...-;. FIG. 157. DIAGRAM SHOWING POSITIONS OF TEST LOADS. THE official and the Board of allowed the whole of the stations inspection testing by on structure, the Upward deflection at end post of Inchgarvie Trade took on the 18th Inspectors place Tuesday, were gone over again, both by the Forth Bridge north cantilever, on east side =3| in. and the two The the officers of the on west side February, following days. inspectors surveyors and, subsequently, by Ditto, ditto, = 3J ,, were Hutchinson, R. E. , Marindin, Board of Trade Hutchinson Major-General Major Major-General taking r Fourth Position of Trains. The trains were next K.E., and Major Darwin, R. E., and they were assisted one side and Major Marindin the other. The stations moved into the Inchgarvie north cantilever, the front by Mr. W. N. Bakewell and his assistants, of the in the cantilever end piers and at the vertical engines 6 bays into the north central girder the Fortli Bridge Surveying Department. columns were taken as fixed points, and all other rear engines 40 ft. outside Inchgarvie north vertical The conditions, as regards the structure, were the levels were referred to these as benchmarks. columns. The results were : same as on the occasion of the trials preliminary First Position of Trains. The trains were now the : Ballast, of coarse Deflection at end of north excepting following consisting moved side by side over the south approach viaduct post Inchgarvie screened to the extent of about 600 had at east side gravel tons, and along the south cantilever until the cantilever, =7Jin. over the laid Queensferry been distributed structure, being over Ditto, ditto, on west side ...... = front engines were close to the south vertical columns. 7J ;J the buckle -plates in the 6-ft. way, and between the Deflection at end of Fife south canti- Levels were now taken on both sides at every station, post of the two lines ; on the other hand a consider- on east side troughs but maxima are here recorded the intermediate lever, =2 ,, of only able amount staging suspended from the cantilevers Ditto, ditto, on west side ...... =2 deflections were throughout in proportion. ,, and central girders had been removed. The dead- Upward deflection at end of Deflection at ends of 2 and 3 on east side in. post Inchgarvie weight in the end boxes of the two fixed cantilevers Bays =\\ south cantilever =3 westside=l in. ,, had also been increased to 1000 tons in each case. ,, ,, on west side Ditto, ditto, =3| ,, The trains used on this occasion consisted of : Second Position Trains. The trains were next of This concluded Tuesday's work. moved forward on to the north 2 Locomotives and tenders in front ... 146 tons. Queensferry cantilever, Wednesday, IQth February, 1890. The of 44 with the front engines being 6 bays into the south central position Wagons (loaded pig iron) at 15 the locomotive were reversed this one tonslOcwt girder the rear engine being about 40 ft. clear of the engines day 682 ,, in in rear. vertical results front, two The weights and lengths of 1 and in Queensferry north columns. The were Locomotive tender rear 73 trains remained the same. as follows : Fifth Position of Trains. The trains were first Total for each train... 901 ,, Deflection at end posts of Queensferry north for moved into the Fife south cantilever the front en- Or both trains... 1802 ,, cantilever, on east side ...... = 7| in. gine about 40 ft. short of the Fife south vertical The length of each train was : Ditto, ditto, on west side ...... = 7jj,, columns the rear 6 within north central 3 Engines ... 144ft. Deflection at end post of Inchgarvie south engines bays The results were: .. . ft. in. .. = girder. 44 752 5 on east side ...... 2 Wagons cantilever, J ,, side ... = Ditto, ditto, on west ...... 2J ,, Deflection at end post of Fife south canti- ft. in. close Total 896 5 buffered. deflection in Queensferry south can- lever, on east side ...... = in. Upward "7J = ; tilever at end of 3, on east side ... on west side ...... = The load was thus somewhat more concentrated bay li,, Ditto, ditto, J , , on west side ...... = at of than on the first occasion. Ditto, ditto, 1^,, Deflection end post Inchgarvie north on east side ...... =2 Along the footpaths on both sides of the internal Third Position of Trains. The trains were then cantilever, ,, on west side viaduct stations had been prepared by driving in moved on to the Inchgarvie south cantilever, the front Ditto, ditto, =2J ,, copper tacks upon which the levelling staffs were engines being about 40 ft. short of Inchgarvie south ; Upward deflection in Fife north cantilever placed. There was a station at the centre of each vertical columns, the rear engine 6 bays in south of on east side ...... = 1 End Bay 2, ^ , , tower, at each of the vertical columns, and at the central girder. The results were : = ,, ,, on west side 14 ,, ends of each in the cantilevers, also at each end Deflection at end of south bay post Inchgarvie End of on east side = = Bay 3, lj ,, ami at the centre of the central connecting girders. cantilever, on east side ...... 7Jin. = ,, ,, on west side ...... 1A. ,, had been levelled several side ... = All stations times over, and Ditto, ditto, on west ...... 7J ,, carefully checked and plotted. On the morning of Deflection at end post of Queensferry north Sixth Position of Trains. The trains were then the inspection, and previous to any train being cantilever ...... not observed moved into the Fife north cantilever the front engii e outside the north cantilever end pier upon the via- passage at speed of heavy trains, and these agreed and terminating in the afternoon of the 3rd day in a ductthe rear engine 40 ft. short of the Fife north exactly with those obtained during the deadweight storm of sleet and rain. vertical columns. The results were as follows: trials.) The report by the Board of Trade Inspectors issued Deflection at end of bay 3 in Fife north can- For testing the deflections in the central connecting on February 24, 1890, is of a highly satisfactory . . = 1 tilever, on east side ...... in. girders two trains were made up, consisting each of three and complimentary character, and enters into every = Ditto, ditto, on west side ...... 1J ,, engines and six trucks at each end, these trains question of interest to the travelling public. After this various trials were made with the trains weighing 405 tons each, or a total weight of 810 tons On March 4, 1890, during a violent gale which running abreast at moderate speeds, and up to about upon each girder. Both in the north and south spans blew from the south west with a pressure of 20 Ib. per 20 miles per hour. During these trials observations the application of this load produced a deflection of square foot, the Prince of Wales closed the last rivet were taken of the deflections to north or south, as the slightly over li in. at the centre of the girder. in the north central girder, and from the south port case might be, of the tops of the vertical columns with The test loads applied to the 168 ft. spans of the of the south cantilever end pier declared the bridge the passage of the heavy trains. The observations approach viaducts produced deflections ranging from open. At the banquet which followed the ceremony, and were taken by means of theodolites placed on the }i in. to Jj in., or a mean of J in. to which nearly 600 guests had been invited, the Prince circular to the various Various with trains in of granite piers. Referring again special trials running opposite Wales_ announced that the Queen had conferred upon positions of the trains as above, the movements noted directions, and meeting each other at specified points, the Chairman of the Forth Bridge Company, Mr. were as follows : also took place. Matthew William Thompson, and upon Sir John Fowler, K.C.M.G., the honour of baronetcies; upon First position not observed see 6th position. Ml. Mr. Benjamin Baker the honour of K.C.M.G.; and Second Queensferry vertical columns moved towards north 2 upon Mr. William Arrol, the honour of a knight- 1 hood. Inchgarvie , south 2 Between five and six o'clock Third ,, , south the same night two 2 Fourth , north heavy goods trains passed over the bridge one from Fife south 2 north and one the Fifth , from south, and commencing from 1 of the March Sixth. . , north morning following day, Wednesday, 5th when passenger traffic between Dunfermline and From a suitable station near the old castle on Inch- The atmospheric conditions during the three days Edinburgh was established between 40 and 50 trains have been run com- s,,were .also taken of the deflections were not of the most agreeable character an extremely every day and night over the now he four free cantilevers during the cold and stiff easterly breeze blowing the whole time, peted Forth Bridge. PRINTED AT THE BEDFOKl" PRESS, 20 AND 21, BEDFORDBURY. LONDON, W.('. THE FORTH tWTH j . ftttUSftlUtt HI* Fuj I f\ SOCK ifST^j^vr! '' *" '**"" l ! '"^V^-*V I Sj.V*^!i?*ri"^ 'V?^23^^^ Central Tower Central Cross Section at Bracing at vertical column Centre of Pier. INCH-GARVIE PIER : FIFE & QUEEN il S53SD PLATE III. am aoo imtf cn/ic//vos 5 at of toy end Bay 5 at upper portion y6. oc t ween Struts a n A c / c a ietr. Struts THE FOR' 1111 iliSiiil ^ lilMSifIr t' , , if;;llfi ^.. fil ^1 GENERAL VIEW OF BKIDGE. SOUTH CENTRAL GIKDEB CONNECTJ PLATE IV. 1H BRIDGE. r&n!gRRi t, NORTH CENTRAL U1KDER NOT COMPLETED. PLATE V. THE FORTH BRIDGE. GENERAL VIEW OF SITE LOOKING NORTH-EAST. CAISSONS BUILDING ON LAUNCHING WAYS. o w I o ks Q to p c a M p M ii H THE F O R 1 H LAUNCHING OF CAISSON FOR SOUTH-WEST PIER, INCHGARVIE. BUILDING OF NORTH-EAST CIRCULAR GRANITE TIER, INCHGARVIE. PLATE VII. TH BRIDGE. GENEKAL VIEW OP SITE, WITH PIERS OF SOUTH APPROACH VIADUCT, LOOKING NORTH. CAISSON FOR QUEENSFERRY NORTH-WEST PIER. CONSTRUCTING TIMBER CASING ROUND THE TILTED CAISSON. w o Q t & PQ K h P4 O fe w K H B 9 g O a;-> 3 ga o H P 9 O61 I s THE FOR OF LIFTING PLATFORMS. FIFE PIER. EKF.CTION OF SUPERSTRUCTURE ; CONSTRUCTION PLATFORMS ABOUT 100 FT. A DOVE HWJII WATElt. FIFE FIEK. ERECTION OF SUPERSTRUCTURE ; LIFTING PLATE IX. H BRIDGE. PIER. OF SUPERSTRUCTURE RIVETTING CAGES AND HYDRAULIC RIVETTING VERTICAL SI ERECTION ; MACHINES ON COLUMN AND DIAGONAL RUT. CAGE FOR BUILDING AND KIVKTTING I'.O'ITOM MKMISKKS. > 2 H o 3 s o X E' I R I B H Oi_> PH O f. Ej 8" a g W z S3 5 1 !5 g H W K S a w 3 S o b Q m I I P4 PQ - M H P4 O fe W W H a 3 E K g A I 3 w o Q H ^ O to w a h THE FOR1 EFFECT OF SEA FOG. CENTRAL TOWERS AND SOUTH APPROACH VIADUCT. GENERAL VIEW OF CENTRAL TOWERS AND APPROACH VIADUCTS LOOKING NORTH. PLATE XIII. BRIDGE. H.M.S. "DEVASTATION" PASSING THE FIFE PIER. QUEENSFEKRY NORTH-EAST PIER. PUTTING TOGETHER UPPER BEDPLATE. w o Q i i & PQ ffi H O I aI W W H THE FOR FIFE PIER. FIRST HALF-BAY IN FIXED CANTILEVER, SHOWING LIFTING PLATFORM J'OK BUILDING THE LOWER PORTION OK BAY AND TOP MEMBER CRANE WITH PLATFORM SUSPENDED FROM IT. PLATE XV. H BRIDGE. MAKING GOOD A CROSSING BETWEEN STRUTS AND TIES IN FIRST HAY OK CANTII.KVEKS. W O Q h p^ O fe w ffi h THE FORT FIFE PIER. LOWER HALF OF FIRST BAY IN FIXED CANTILEVER. PLATE XVII. i BRIDGE. FIFE PIEK. CENTRAL TOWER AND LOWER HALF OF F11WT BAY IN FREE CANTILEVER. THE F O R 1H FIFE PIER. FREE CANTILEVER COMPLETED AND CENTRAL OI PLATE XVIII. I BRIDGE. R COMMENCED FIXED CANTILEVER NOT QUITE COMPLETED. a (jit ; THE FOR: QUEENSFERRY PIER AND INCHGARVIE SOUTH CANTILEVER, WITH PARTS OF CENTRAL GIRDEK BUILT OUT. INCHGARVIE SOUTH CANTILEVER, WITH FIRST BAY OF CENTRAL GIRDER BUILT OUT. PLATE XIX. 1H BRIDGE. CENTRAL TOWER OF INCHGAKVIE ; INTERNAL VIADUCT O1RDERS AND WI31> FENCE.