The Simplon Tunnel.” by Francisfox, M

Home , Diveria, Simplon Pass, Simplon Tunnel, Wasenhorn

Proceedings. J ELECTIONS. 61

Associate Members-continued. CHARLESWILLIAX HARRIS. WILLIANGEORGE NELVIN. JOHNEDWARDHENSXAN, B.A.(Madras). ALFREDWILLIAM OKELL, B.A. (Can- DANIELPETER HONELLS. tab.) HERBERT RICHARD HYATT. ARTHURPOPE. EDWARDROBERT HOULTON JACKSOX, ROBERT SIYOND RAXKEN. Stud. Inst. C.E. DOUGLAS HENRY RENFRT. COSMO REYNOLDJOSES. THOMAS CASSELLSRow. THOYASJOHN RANSOY KIERNAX, B.Sc.ALFRED ERNEST RUFFHEAD. (Engineering) (Load.), Stud.Inst. WILLIAMHAMILTON SHORTT, Stud. Inst. C.E. C.E. FREDERICKOSCAR KIRBY, MSc. (Han- HENRYJOSEPH TRIVEBS SXITH. chester and Leeds), Stud. Inst. C.E. GEORGE HIAM WHITEHOUSE. CHARLES DELACOUR LE MAISTRE. EDWARDPARNELL WIDDICOXBE, B.A. JAMESLUSK, B.A. (Cantab.) (Cantab.) NORMANROWE LYTH. WILLIAMROWANWILSON, B.Sc. (GZas.) JOHNMCLEAN. JOHNWOOD. HAROLDBERTXUI MATHEN, Stud. HERBERTJAMES YOtESG. Inst. C.E. Associates. LYNDENLITINCSTOS MACASBEY,M.A., JOHNMACAWLAY. LL.D. (Dubl.) I

(Paper No. 3651.)

“ The Simplon Tunnel.” By FRANCISFox, M. Inst. C.E. THErouteover the Alps, by way of the Simplon Pass, has existed in one form or other since time immemorial ; and, although it originally consisted only of a footpath, yet there are remains of Roman culverts and bridges. Documents dating from the thirteenth and fourteenth centuries show that a toll-bar and a hospice were in existence in those days ; but up to the end of the eighteenth century the road was neither safe nor convenient. In March, 1801, soon after the battle of Marengo, the present roadway was commenced by order of Napoleon, and it was finished in September, 1805. The length of the highway is 37& miles, andits construction necessitated the building of 611 bridges and culverts, together with seven galleries for protection from avalanches, or through rock. The costwas 2303,000, in addition to the compulsory labour, or “ CorvQes,”of about 700 peasant,s. Between the years 18521 and 1893, no less than thirty different proposals for traversing the Simplon by railway were put forward. Of these, two were designed to scale the mountainswithout sub-

terranean work ; and the remaining twenty-eight proposed tunnels of various altitudes andlengths. In 1891 the Jura-SimplonRailway Company brought forward their project, and subsequently, in 1893, the one which has now been completed, namely, a low-level line with easy gradients, as being the only rational method of enabling them to compete with other Alpine railways, and affording a prospect of a return upon the capital required. Plan.-By adopting thelevel of the railsof the existing railway at Brigue, all expense of heavy approach-lines and helical tunnels on the Swiss side is avoided ; and the railway enters the mountain a few feet above the level of the Rhone. It passes infour places beneath the Simplon roadway, one being under the picturesque village of Berisal ; after which point the gallery attains its greatest elevation at about 9 * 1 kilometres (5 ~65miles) from the northern entrance, between the Wasenhorn and the Furggenbaum Pass, and goes through rock and under glaciers at a depth of 2,100 metres (6,888 feet). The greatest depth below the surface attained is 7,005 feet, namely, beneath the slopes and crags of Monte Leone, the highest mountain of the Simplon range, 3,561 metres (11,684 feet) above sea-level : this is by far the greatest depth to which man has ever been below the surface of the earth. After passing under the Lake d’Avino, it proceeds to its southernportal at Iselle, a distance of 19,803 metres (21,657 yards, or 12 miles 537 yards). This length includes two short curves, one at each end ; but the “gallery of direction,” which for triangulation purposes is driven in a straight line from end to end, is 19,729 metres (21,576 yards) long. The following Table gives the comparative lengths and altitudesof the Alpine tunnels :-

1 Mont Cenis. ! St. Gothard. 1 Arlberg. 1 Simplon. 1 12 819 m. I 14,981 m. I 10,240 m. 19,803 m. . ‘((14,b52 yds.)(16,387 yds.)(11,199 ycls.)(21,657 yds.) Altitude of the highest 1 1,294 m. 1,151 m. ’ 1,310 m. 705 m. point above the sea .]l (4,245 ft.) 1 (3,786 ft.) I (4,299 ft.) 1 (2,313 ft.) Maximumthetunnel gradieut . . 1 in45 i”)i 1 in172 1 in 66 1 1 in 143 1

Not only is the Simplon the longest tunnel in the world, but it is also the lowest in altitude of these four. The position of the entrance onthe southside was determiced by two things, namely, the dimate, and theextremely narrow characterof the valley of the River Diveria. As regards the climate, it was well known that sleighs could reach Iselle erery winter, the depth of snow up to

that point not being formidable, whereas a short distance higher up the valley becomes impassable. With reference to the width of the valley, this increases somewhat at Iselle, and although the valley is still very narrow, and consequently inconvenient, it was found possible toarrange there the various buildings and installations necessary at .the terminationof the tunnel. Gradients.-The position of the portals having been thus fixed, the gradients also were practically settled. It wasobvious, from the experience of previous tunnels, that the gallery must be driven on an ascending incline from both ends, so that the water might flow away by gravitation. In the Mersey tunnel a minimum gradient of 1 in 500 was found to give the water a sufficient flow. In 1893 the same gradient of 1 in 500 was adopted for the northern half of the Simplon. tunnel, involving agradient of 1 in 143 for the southern half, and a length of 526-9 metres (577 yards) has been provided in themiddle, for the passing and shuntingof trains, by the construction of two complete single tunnels (Fig. 1, Plate 3). At the point of culmination, however, the Brigue gradient of 1 in 500 has been connected with the Iselle gradient of 1 in 143 by a vertical curve of 10,000 metres (497 chains) radius for a length of 80 metres (87.5 yards). Cross Secfion.-Instead of making one tunnel for a double line of way, as in the St. Gothard and Mont Cenis tunnels, two single-line tunnels, 17 metres (55 8 feet) apart between centre-lines, with cross oblique passages connecting them at every 200 metres (218- 7yards), were designed. It was arranged that one tunnel only should be built at first, witha rarallel gallory, and thisgallery is to be enlarged for the second tunnel when, according to the internationalagreement between Switzerland and Italy, the gross receipts exceed 23,218 per mile per annum. Each tunnel was designed to have a minimum internal area of 23 20 square metres(249 73 square feet), witha width at rail-level of 4-50metres (14 feet 9 inches), and at the carriage-windows of 5 metres (16 feet 5 inches), the height above rails being 5-50 metres (18 feet 3 inch) : thus ample space has been given on both sides and above thetrain for air, and1 for carrying out repairs when necessary (Figs. 2, 3 and 4, Plate 3). The importance of providing two single-line tunnels in this case cannot be over-estimated, and experience hasfully justified their adoption. In fact,the Author has no hesitationin saying that had not thisbeen arranged originally, the work would hare proved impossible to carry out, and mould have had to be abandoned for reasons given later on. Galleries.-Two galleries were excavated, No. 1 forming the present tunnel, cnd No. 2 being parallel to it, and the latter was

used as the“ in-bye ” for the fresh air from the outside, which blewthe vitiated air from the workings through the last transverse gallery (Fig. 5, Plate 3). Each of the previous “ cross cuts ” was provided with double doors, so that the air-currentscould be regulated in any way desired ; but it was found that so mach air escaped through them that they have been closed by masonry, with the exception of one such gallery at each kilometre, where a door is provided of sufficient size to allow one man at a time to pass. It was only the most advanced transverse passage that was left open for the air to circulate freely, thus securing good ventilation. These galleries formed the bottom heading, and were kept 500 to 1,000 yards in advance of the“break-ups ” andtop headings. The second gallery now provides for one of the channels for conducting the water from the springs to the outside of the mountain, and also for the pipes and conduits ; and it served for transporting material during construction(Fig. 6, Plate 3). Wheneverrepairs may require to be executed in the arching of the work without stopping the traffic, they can be far more easily effected in the case of two single-line tunnels than in one of double line ; for the trains would be diverted forthe time being, andthus the timbering for the repairs would not have to be so arranged as to allow traffic to pass. In the event of derailment of a train, the passing vehicles would not be exposed tothe danger of collision ; and, finally, where great pressure comes on tothe lining of the work, it would be far less in a single-line than in a double-line tunnel, a matter whose great importance has been proved by actual and very anxious experience. In fact, it is the opinion of those connected with the work that it would otherwise have been practically impossible to make the lining strongenough to resist such pressure as was encountered at a point about 4.4 kilometres (2 miles 1,292 yards) from the south entrance. The tunnel is lined throughout with masonry, as it was deemed undesirable to run therisk of any such occurrence as the fall of a block of rock on to the line during traffic. Four different sections of masonry are shown in Figs. 2,3, and4, Plate 3 ; but during the execution of the work far greater thicknesses were found to be necessary, that at 4.4 kilometres (2 miles 1,292 yards) from Iselle attaining 5%feet of granite blocks (Fig. 14, Plate 3). On the west side of the tunnel, thatis, on the right-hand side entering from Brigue, a small safety manhole 7 feet wide is provided at every 50 metres ; whilst at every 200 metres the transverse gallery serves as a refuge. In the length of the tunnel, four large rooms are built for the use of the workmen andtheir tools, trollies, etc. : these rooms are 4 metres (13.12feet) wide, 3.10 metres (10.17feet) high, and

Downloaded by [ UNIVERSITY OF OXFORD] on [13/09/16]. Copyright © ICE Publishing, all rights reserved. Proceedings.] FOX ON THE SIMPLON TUNNEL. 65 6 metres (19.68 feet) long. On the east side, at every kilometre (1,094 yards), a small room, 3 metres (9 - 84 feet) each way, is provided for signals, and for the junction of the electric cables : it is at these points that by means of electric light the number of kilometres is indicated for the information of the locomotive-drivers. The Author is strongly of opinion that every tunnel exceeding a $ mile inlength ought to be constructed witha room for the men, furnished with a cooking-stove and seats, in order that they may be able to heat their food, and have their meals, protected from the draught andsmoke of the tunnel. Programme.-On the 20th December, 1890, an association represented by Messrs. Sulzer of Winterthur,and Messrs. Brandt, Brandauand Co.of Hamburg, as contractors, presented tothe directors of the Jura-Simplon Railway Company the project for piercing a tunnel of low altitude, and in July, 1891, the railway- company handed to the Federal Government definite plans for its construction.Doubts, however, were cast by certainengineering authorities upon the possibility of constructing thetunnel; and, in consequence of this,the Swiss Confederation requested the Governments of Italy, Austria, and England each to nominate an engineer having experience of tunnelling, to form a “ commission of experts,” whose business it would be to examine the programme and proposals, and theplans and estimates, and to report to the President of the Swiss Confederation. The Government of Italy nominated the Hon. Giuseppe Colombo,Member of the Senate, andafterwards Minister of theTreasury; Austria appointedMr. C. J. Wagner, Chief Government Inspector of RailwaysinVienna, and thecelebrated engineer of the Arlbergtunnel, whilst theBritish Government nominated the Author. These three engineers satat Berne for some time considering the plans and estimates, and going into every detail;the proposed systems of drilling and ventilation were laid before them, and, after examining the site of the tunnel and the proposed entrances, they drew up and presented a report to the President and the Swiss Federal Council in July, 1894. Upon this programme of the engineers and contractors, confirmed bythe report of the committee of experts, thetunnel has now, notwithstandingits unique and unprecedented difficulties, been successfully constructed; and it is interesting to find that all the various methods which were devised and proposed for carrying out this work have been employed with the greatestsuccess. Mr. Brandt, whose lamented death occurred soon afterthe commencement of the works, had had a wide experience on the St. Gothard tunnel, which enabled him to devise and introduce many improvements in [THE INST. C.E. VOL. CLXYILI.] F Downloaded by [ UNIVERSITY OF OXFORD] on [13/09/16]. Copyright © ICE Publishing, all rights reserved. 66 FOX ON THE SIMPLON TUNNEL. winutes of the machinery and installations. His placewas taken by Colonel Locher-Freuler, of Zurich, the celebrated engineer who constructed the Pilatus railway, the most daring piece of work of its day: he planned and constructed all the installations at Brigue and Iselle. Considering its importance and magnitude, this work was done with a rapidity which has never been equalled, forthe line of access at Brigue was executed in 1 month, and 250-HP. engines were in operation in 3months, whilst the hydraulic machinery at Brigue and Iselle, aggregrating 4,185 HP., was ready in14 months. Messrs. K. Brandau, Edward Sulzer and Locher-Freuler formed a remarkable combination of financial and mechanical skill and dogged determination, which absolutely refused to admit defeat where so many pronounced the difficulties encountered to be insuperable. Hence it is that Switzerland is proud of the men who have successfully carried through this work, and has conferred upon them, as also upon Mr. Zollinger, Mr. Pressel, Baron von Kager, and Pro- fessor Rosenmund, the well-merited degree of Doctor honoris causa. Mr. Sulzer has stated in public that, had the geologists been quite accurate in their preliminaryinvestigations and reports, and had they truly and correctly anticipated the dangers and obstacles which were eventually met with in soft rock, the “ Great Spring,” or river of cold water, the hightemperatures andhot springs, andthe “ creep ” or lifting of the floor, no one would have dared to undertake the contract, and the tunnelwould never have been constructed. On the 25th November, 1895, the Jura-Simplon Railway Company, then represented by its President,the late Mr. Ruchonnet, and by Mr. Dumur, signed a convention forthe Simplon tunnelat Rome with the Italian Government, and in December of the same year it was ratified by both countries. Theestimated cost was 76,010,000 francs (%3,040,400),and towards this the Swiss Federal and Cantonal Governments, withother contributions, subscribed 16,260,000 francs (&3550,400), to which must be added contributions from the Italian Government, the Provinces of Milan and Genoa, Novara and Alessandria, and various cities, amounting to 4,000,000 lire (X160,000), thus making a total free gift of 20,260,000 francs (g810,400). Contract.-Under the contract, dated 15th April, 1898, the first tunnel was to be completed in 5 years and 9 months, a further 4 years being allowed for the enlargement and completion of Gallery No. 2 into a second tunnel ; but alterations were made, both in the time, which was extended by 12 months, andin the amount of the contract, whichwas raised to 78,000,000 francs (Q3,120,000). The specification stipulated for excellent ventilation in all the working-

places inthe tunnel, and the maintenance of atemperature not exceeding 25' C. (77" F.), the necessary conditions to be obtained by theaid of jets of sprayed water:further, a good supply of drinking-water in all the working-places was to be provided, together with free baths for the workmen, whilst healthy lodgings and good food at low prices were to be placed within their reach. When it is remembered that this specification was in large measure drawn up by the contractors, it can safely be said that the solicitude and care evinced for their workmen has been an object-lesson to the world. It WAS intended that half of the tunnel should be built from the Brigue entrance, and the other half from Iselle, so that all the work should bedriven on an ascending gradient. Accordingly, the machinery installed at each placewas laid out with this object in view;but eventuallyvery considerable modifications had to be introduced. On the 12th August, 1898, the Jura Simplon Company notified Messrs. Brandt,Brandau and Co. of their acceptance of their contract, and next day the necessary land was placed at their disposal. Geology.-The rock consists chiefly of gneiss, mica-schist, and on the Italian side of antigorio gneiss, but in some places, particularly about 4.4 kilometres (2-73 miles) from Iselle, limestone was encountered. It is lustrous in appearance, commonly known as "sugar marble," and highly charged with springs of cold water, having a temperature of 11" to 17" C. (52" to 62.6' F.). In the vicinity of this marble the stratification revealed a soft, easily disintegrated micaceous rock, which under the action of water worked intoslurry ; and it was inthis that some of the worst trouble was experienced. So long asthe Brandt perforators hod good hard rock in front of them, they made splendid progress ; but when soft rock was reached, necessitating timbering, the advance naturally fell off, andin some cases excavation by hand had to be adopted. Great pressure was encountered in places where the geologicalbeds were horizontal, and much heavy timbering was required. Triangulation.-A survey had been made in 1878 in connection with the proposal of thatdate, and it sufficed for the first few kilometres ; but the actual triangulation was entrusted to Mr. Max Rosenmund, Engineer of the Federal Topographical Department, and since Professor of Geodesy at the Federal Polytechnic School of Zurich ; and it is due to this gentleman that both levels and lines of this great tunnelhave proved to be so accurate. The plan of triangulation comprised Monte Leone, 3,561 metres (11,670 feet) above sea- level, and there were in addition ten other stations, including t8he F2

Downloaded by [ UNIVERSITY OF OXFORD] on [13/09/16]. Copyright © ICE Publishing, all rights reserved. 68 FOX ON THE SIMPLON TUNNEL. pinutes af two axis-points ; and it was necessary that three of these should be visible from any point of observation. The survey was linked up to the Wasenhorn-Faulhorn line of the geodetic survey, which connects the Simplon astronomical station with the most important points of the Swiss measurement of the degree. This acted as a base-line for the calculation of the length of thetunnel; and it was not re- measured, asthe maximum error whichwas expected was not greater than 0.8 metre (31 5 inches). The measurement of the angle occupied 41 days, the instrument used, made by Messrs. Kern & Co. of Aarau, having a horizontal circle, 21 centimetres (8t inches) in diameter, and a vertical circle of 16 centimetres (64 inches). One division of the micrometer- drum represented 4 seconds; andthe vertical circle gave direct vernierreadings of 10 seconds. The average closing-error of the triangles was 3.1 seconds ; and the maximum, which occurred in the steepest sight of 23" 40', was 8 -5 seconds. By introducing corrections for the action of the mountain masses, the mean closing- error of the triangles was reduced to 1*7 second. For the purpose of setting out, an observatory was built at each end near the axis- points ; and permanent levels and lines were checked twice a year, the entire work of the tunnel being suspended during 24 to 32 hours for the purpose. A beam of light was projected into the gallery ; and the ventilation was so good that it could be seen by the naked eye more than 5 miles " in-bye."Owing to the difference in the refractive power of the cold air outside and of the warm air of the tunnel, the beam of light, which came through a vertical slit in the lamp-screen, was bowed over at the top in theform of a portion of an arch. Final 3leasurements.-The following are the final results of the actual measurements. The axis from thenorth end deviated 110 millimetres (43 inches) towards .the west; and the axis from the south end deviated 92 millimetres (3; inches) towards the east. This gave a total divergence of the two axes of 8 inches, or a maximum from the true line of 43 inches. The difference in levels proved to be 87 millimetres (34 inches). The total length was found to be 79 centimetres (31 inches) less than was anticipated, or almost precisely the error that was expected. In all the Alpine tunnels except the Mont Cenis thelength proved to beless than was calculated, namely, theSt. Gothard, in 15 kilometres (9 3 miles), 7 * 6 metres (24.93 feet) shorter ; the Arlberg, in 10 kilometres (6 * 36 miles), 3 metres (9 84 feet)shorter ; and the Simplon, in 20 kilometres (12.26 miles), 0.79 metre (2.59 feet) shorter ; whereas the Mont Cenis tunnel (13 kilometres, op

7-98 miles), proved to be several metres in excess of the calculated length. Water-Power.-Itwas intended thatthe installations inthe valleys of the Rhone and the Diveria should eachbe of sufficient magnitude to deal with one half of the tunnel ; but owing to great delay, caused chiefly by the above-mentioned dangerous ground at 4.400 kilometres (2.73 miles), it was eventuallyfound necessary forthe work, asfar as 10.376 kilometres (6.448 miles) from Brigue, to be executed from that end. Full particulars of the water-supply and channels, as also of the Brandt drill and method of working, have been given in a Paper 1 by the Author’s son, Mr. Charles Beresford Fox, Assoc. M. Inst. C.E., and it is therefore unnecessary to repeat what is there described except very briefly. At bothends of the tunnel, steam installations of three semi- portable engines and boilers were provide,d, each giving 250 to 300 HP., which were used to work the drills at the earliest possible moment. They commenced operations at Brigue on the 22nd November, 1898, and at Iselle on the 21st December, 1898. The hydraulic power from the Rhone and the Diveria was put in operation in the autumn of 1899; and from that time the steam- engines only worked occasionally, for a few hours or a few days as required. In 1904 a locomobile was taken to Iselle, and was fixed at 4.4 kilometres to work the pumps for refrigeration. Thewater for the hydraulic pumps at Iselle was obtained from apure springup the mountain side, whilst at Brigue it was taken from the Rhone. Owing,however, to a considerable quantity of quartz coming with the waterfrom the river during the summer, the water had to be filtered through sand and gravel. Inthe Brigueinstallation, the riverwater wasconveyed by gravitation through a ferro-concrete aqueduct, 3,200 metres (3,500 yards) in length from the village of More1 to Massaboden. Thence it was carried throughwrought-iron pipes, 1 60 metre (5.25 feet) in diameter,under pressure, tothe turbine-house, having a head of 44.5 metres (146 feet), and furnishing aneffective force of 2,225 HP. On the south side the works were very similar : a pressure-main, 0.90 metre (35 -43 inches) in diameter, extended for a distance of 4,210 metres (2.62 miles). Of this length 1,160 metres (1,269 yards) were of cast, iron, and 3,050 metres (3,335 yards) of steel. They took

-. ~ ~ ‘‘ The Construction of the Simplon Tunnel.” Minutes of Proceedings Inst. C.E., vol. cnl, p. 249.

Downloaded by [ UNIVERSITY OF OXFORD] on [13/09/16]. Copyright © ICE Publishing, all rights reserved. 70 FOX ON THE SIMPLON’ TUNNEL. minutes of 1 146 cubic metre per second (15,130 gallons per minute) from the river with a head of 177 metres (580 feet), and developed 1,960 effective HP. in the turbines. The turbines worked the pumps, which delivered their water at 100 atmospheres pressure, into thehydraulic main traversing thegalleries, and up to theadvance headings in which the Brandt drills worked, the available pressure at thepoint of attack being 76 to 90 atmospheres, according to circumstances. Thus the total available power, north and south, was 4,185 effective HP. The Brandt drill consists of a stretcher-bar (itself an hydraulic ram) mountedon a portable carriage, and provided withthree hydraulic engines each actuating adrill. This is 2% inches in diameter, and can be worked in any direction ; it can be advanced or withdrawn at anydesired speed, and the changing of the tool can be effected in 10 seconds, Thedrill is rotatory in its action and non-percussive, being kept up toits work with apressure of 10 tons ; and as the discharge-water is delivered through the centre of the tool to the cutting edges, the dust produced is at once turned into mud, and at thesame time the steel is kept cool. Sanitary Arrangements.-The sad experience of the St. Gothard tunnel called attentionto the great necessity forameliorating the conditions of the employees. In carrying outthat work, between 1872 and 1880, no less than 800 of the workmen died, including both the contractor andthe engineer, andthis enor- mous death-roll was essentially due to defective hygienic conditions, tothe high temperatureand small supply of air inthe interior of the galleries, to the severity of the climate, and to the sudden transition from heat to cold. In addition to these muses, were the want of proper provision for changing the wet garments of the men, andthe dust produced by the drilling-machines. A special disease called miner’s anaemia,now better known as “ anchylostomiasis,” which is characterized by the presence of a small worm, “ dochmius duodenalis,” in the intestines, propagated itself with terrible rapidity in the St. Gothard tunnel-works. In the Simplon tunnel, whichwas eminently favourable to the disease, it was absolutely unknown. Excellentarrangements were made for the complete ventilation of the innermost workings and the most advanced galleries, and for every cubic foot of air which was blown into the St. Gothard tunnel, twenty-five were supplied to the workmen inthe Simplon. Not only did the ventilating-fans keep up it steady current of air along one gallery and back by the other, but, by an ingenious system of aspirators, a large volume of fresh air was blown into the dead ends of the galleries, which were thus kept perfectly fresh, and the current was strong enough to

blow a man's hat off. In fact, such a thing as vitiated air was unknown throughout the work, and would have been regarded as a slur on the management. The primary ventilation was effected by fans driven by hydraulic turbines at 380 revolutions per minute, which delivered as much as 8,600,000 cubic metres (303,723,000cubic feet) of airin about 24 hours, equivalent to 210,920 cubic feet per minute.The secondary ventilation from the aspirators was accomplished in the following manner. From the high-pressure main in Gallery No. 2, conveying water to the drills, a small pipe was led into the open end of a light sheet-iron tube, 15 inches in diameter, and a jet of water, -& inch in diameter, was directed along this tube, thereby not only drawing in a large volume of fresh air circulating in the primary ventilation from the fans in the tunnel, but also cooling that air very considerably. One of these tubes was found to convey as much as 1,000 cubic feet of air per minute through a length of 160 yards. In an experiment at Winterthur, a similar jet, at a pressure of about 8 atmospheres, was found to cool air, initially heated to 65" C., down to 15" C., afall of no less than 50" C. (90" F.). Besides the aspirators, a system of water-sprays was established at various points in the tunnel, throwing a spray of cold high-pressure water (10 to 25 atmospheres) entirely across the passages, and these had excellent effect in cooling the air (Figs. 7, 8 and 9, Plate 3). The Author desires to urge strongly the immense importance, for the progress of work, forthe health of the staff and workmen, and for financial interests, of supplying every working-place in a tunnel with an ample volume of freshair. Much more work is done, the health of all is preserved, and themany indirect economies result in reduced cost. Notwithstanding all his efforts, he has never known the working-face of a "tube" railway, and very seldom that of anordinary tunnel, to be properly ventilated. He, however, desires to mention the excellent ventilation provided in the wses of the Greenwich Footway tunneland of the Blackwall, Rotherhitheand other tunnels drivenunder compressed air,in which a very large volume was forced in between the air-locks and the working-face. Nextin importance to good ventilation were the excellent arrangements for enabling men to change their clothing. At each end of the tunnel, and connected with it by a covered line of railway,was a large building fitted with dressing-rooms and hot and cold douche baths. Fromthe roof of the building, which was heated by steam-pipes, hung 1,500 ropes passing over pulleys, each with its padlock. On the other end of each rope was a hook upon

Downloaded by [ UNIVERSITY OF OXFORD] on [13/09/16]. Copyright © ICE Publishing, all rights reserved. 72 FOX ON THE SIMPLON TUNNEL. [Minutes of which the owner could hang all his things, and then, hauling them upto the roof, he left them thereduring his absence in the galleries. On his return from work, he entered a cubicle where he had his bath, and,having lowered his day clothes, he attached his wet mining garments to the hook and hoisted them to the roof adjacent tothe hot pipes, to findthem dryand warm onhis returnto work next day. If his clothes were torn or soiled, they were sent to the laundry on the premises. After changing from hismining into his day clothes, he passed into a restaurant, where he could obtaina substantialhot meal for 4d., and, if he desired, could obtain board and lodging for Is. 2d. per day. An excellent hospital was provided at each end of the tunnel, fitted with every requisite, and these establishments were generally empty. Good arrangements for " Grst aid " were also organized. Welfare of the Workmen.-The Italian miner, even when called upon to work under less favourable conditions, is extraordinarily resistant, owing to his sobriety, his simple life, and, above all, the good qualities of his race. The doctors reported how quickly the miners recovered from injuries andwounds, and the fact thatevery man was medically examined as to his fitness for the special conditions of his work led in time tothose satisfactory results. Protestant and Roman Catholic places of worship and day and Sunday schools were also established. Discipline.-The discipline among the workmen was of the highest order, nearly all of them being Italians, and having been through the Army ; and so long as they were not interfered with by paid agitators, no difficulty from strikes was encountered, and no malingering or shirking of work occurred. They worked in three shifts of 8 hours each, and as no man stopped work until his successor actually stepped into his place, the boring-machines never ceased operations. Ib?nperature.-Judging from the experience of former Alpine tunnels, it was anticipated that considerable heat wouldbe encountered. In the St. Gothard, the maximum temperature of the rock being 31'C. (87" F.), the temperature of the air was 33" to 34" C. (91' to 94" F.), butthis, owing tothe stagnation of the air, was insupportable ; whereas in the Simplon, although the temperature of the rock was 54" to 56" C. (129' to 133" F.), that of theair did not exceed 32" C. (89" F.). This was in no way unbearable, in consequence of the large volume of fresh air travelling along the galleries, and the use of the spraying-devices already mentioned. In order toobtain the best resultsin refrigeration, it was necessary that the water should be as cold as possible, and conse-

quently the pipes had to be lagged in order to exclude the heat of the gallery. The insulation of 10-inch pipes for a distance of 5 to 6 miles involved a difficult problem. The husk of rice was for a time used as a non-conducting material, but, owing tostray grains of rice germinating, it had to be roasted. Thenthe customs-authorities, finding this worthless material was being used, charged a high rate upon it coming from Italy, and it had to be abandoned. Finally, charcoal was employed with excellent results, the water being delivered atits destinationwith a rise intemperature of only 4" C. (7.2" F.), During the advance of the galleries, horizontal holes, If metre .long, were drilled inthe side walls at intervals of 1,000 metres (1,094 yards), a,nd in these thermometers were placed for registering the temperature of the rock. To avoid breakage from the blasting, these holes were necessarily a little in rearof the actual face, and to this extent an element of error was introduced ; but this has been corrected as far as possible in Fig. 10, Plate 3, in which the temperature-curve is given below the section of the Alps, with the corresponding curve for the St. Gothardtunnel. The temperature of the rock gradually falls as soon as the excavation has passed any given point, as shown graphically by the dotted curves of the two series of observations on each side of the centre, of March 1903 and 1904. The maximum temperature was 56°C. (133' F.), in proximity to the maximum depth of tunnel (7,005 feet). At the southernor Iselle side of the Alps, the temperatureof the rock followed approximately the section of the mountains until a distance of about 2,200 metres (2,406 yards) was reached. Then, as the tunneladvanced, the rock-temperature began to diminish, and in the region of 4,000 metres (4,374 yards) it fell rapidly, until at 4,400 metres (4,812 yards) it attained the lowest reading recorded. At this point the " Great Spring " was struck, havinga flowof 800 litres per second (10,564 gallons per minute), and it was evidently owing to this volume of cold water that the temperature fell. Thefirst outburst of water was at a very high pressure, estimated at 42 kilograms per squarecentimetre (600 lbs. per square inch). Now, however, it issues at atmospheric pressure, andhas a temperature of about 18' C. (64" F.) The conditions inthe advanced headings, where hotsprings were encountered, produced highertemperatures of theair and watertravelling down the galleries from the feeders. Thus the dottedline giving the temperatures of March, 1904, on the northern section shows a retardation of the cooling of the rock between 2 * 6 kilometres

and 8 kilometres, and between 1 kilometre and 2 * 6 kilometres ; and,as shown in the diagram, the instruments registered higher readings than was initially the case (Fig. 10, Plate 3). A similar result occurred on the southern section, between the entrance and 4 * 4 kilometres. Obviously, when studyingthe depth-temperature curve of the earth's surface, the phenomena at 4,400 metres from theItalian entrance must be neglected, on account of the exceptional agencies producing the result. The deductions are influenced by many other disturbing factors which modify the results more or less, such as the inclination of the strata, and the natureof the rock. Assuming, however, that ata depth of 10 metres below the snow-clad summits of the high Alps a uniform temperature of zero C. (32" F.) may be expected throughoutthe year; then, out of a total depth of 2,135 metres (7,005 feet), 2,125 metres correspond with a difference of temperature of 54.3' C. (97.9 F.). This represents a temperature-gradient of 1" C. per 39 metres (1" F. for each 71-5 feet).l Probably the observations between 8 kilometres and 13 kilometres furnishthe most trustworthy average of the results ; and this selection gives a relation between depthand temperature of 37 metres per degree Centigrade, or 67 * 5 feet per degree Fahrenheit. The Advance.-Fig. 11 shows the rate of progress, both in driving the galleries and incompleting the masonry. It was anticipated that the completion of the masonry would be approximately 1 kilometre inrear of the advanced headings, andthat the piercing of the Alps wouldbe accomplished about November, 1903, whereas it really took place on the 24th February, 1905 ; and that the arching wouldbe completed about March, 1904, the actual date being September, 1905. The diagram shows that excellent progress was made inthe gallery on the Brigue side, andthat the middle of the tunnel was reached nearly 6 months ahead of the programme ; but, from that point onwards, difficulties and delays occurred, chiefly due to hot springs and from having to drive down-hill. On the Iselle side, work went well until 4,400 metres (2.734 miles) was reached. Before this it was noticed that the temperature of the rock hadrapidly fallen from 33" C. (91.4O F.) to 13" C. (55.4" F.) ; and suddenly, and without warning, the " Great Spring" was metwith. This stopped the advance forabout 6 months, up to March, 1902, by which date the soft ground at this point had been traversed, andhard rock again reached. Again good progress was made until September, 1904, when hot springs

Proceedings Inst. C.E., vol. lviii, p. 392.

were encountered at 9,110 metres (5.659 miles), having a temperature of 45 *4' C. (113 * 7" F.). In order to suppress the heat, a pumping installation was established inthe tunnel at 4,400 metres (2 * 734 miles) ; and pipes were laid along the gallery, by whichcold water was forced upthe gradient to the hot region. For working these pumps, a small turbine, driven by the water supplying the drills at a pressure of 100 atmospheres, was at first employed ; but as the quantity of water was insufficient for both purposes the locomobile referrcd to on p. 69 was installed. Jets Fiq. 11.

25Tp JANUARY,1906 COMPLETION OF PERMANENT WAY. JOT* MAY, 1906 TUNNEL OPENED BY PRESIDENT OF THE SWISS REPUBLIC. 1906 7-

1905

- f- +l304 l903 4- 1902

l901

l900 e *less vi i i i i i i i ijiii , i i i 1 i 1 ~lsse L. O123456789OIDS8765~32IOK?n l?TAUGUST 1898. COMMENCEMENT OF WORKS. 22-ONOVEMBER.1898. COMMENCEMENT OF MECHANICAL BORINC. elm DECEMBER, me. -PROORESS OF ADVANCE GALLERY. ----COMPLETION OF MASONRY. TOTAL LENGTH OF TUNNEL19,803.1 K' - 12 M. 537 Y91 DIAGRAMSHOWIXG PROGRESS OF ADTAKCEGALLERY, AND CONPLETION OF MASOXRYFOR TUNNELNO. 1. of cold water were then thrown into the fissures from which hot water was escaping, whereby the temperature was lowered to such a point that the miners were able to stand it. Springs.-Fig. 12 shows by afull line the flowof cold springs into the workings from September, 1901, to December, 1905, and, by a dotted line, the inflow of hot springs. The maximum discharge of cold water was 1,294 litres per second (17,081 gallons per minute), and the maximum discharge of hotwater 328 litres

Downloaded by [ UNIVERSITY OF OXFORD] on [13/09/16]. Copyright © ICE Publishing, all rights reserved. 76 FOX ON THE SIMPLON TUNNEL. minutes of per second, (4,330 gallons per minute). The maximum flows of cold water occur at the times of melting of the Alpine snows. The volume of 1,149 litres per second (15,158 gallons per minute) in November, 1901,was doubtless dueto the first tapping of the underground reservoirs. Analyses.-The water was frequently analysed by chemists on the spot;and samples taken from a hot spring situated at a point between 9 1 and 9 -4 kilometres from the Italian end were analysed in England. This spring discharged water at the rateof 230 litres per Fig. 12.

i- I l

DISCHAILGEOR HOT AND OF COLDSPRIKGS.

second (3,036 gallons per minute), having a temperature of 45 * 9" C. (114'6" F.), The mineral constituents were as follows :- Grammes per Litre. Grains per Gallon. Silica . . , . . . . , . 0.0132 0.71 Aluminaand ferric oxide . . , . 0.160.0022 Calciumoxide . . . . . , . 0.4910 34.37 Strontium oxide ...... 0.0030 0'21 Magnesium oxide , . . . . . 0.0655 4-59 l'otassium oxide . . . . , . 0.0050 0.35 Sodiumoxide . . , . . . . 0.600.0086 Carbondioxide (combined) . . . 0.0267 1.87 Sulphurtrioxide ...... 0.8000 56.00 - _.- 1.4122 98-86 Combined water and loss . . 0.1098 7-68 - - 1.5220 106.54

A trace of lithium was also present. No barium, csesium, or rubidium could be detected with the spectroscope. An examination of the gases expelled by boiling the water, showed it to contain only the ordinary constituents of the atmosphere. The complete absence of chlorine is believed to be unique, and seems to indicate that the water waspossibly entirely plutonic, havingnever beenon the surface of the globe. To provide for the escape of the water from the springs, a culvert, lined throughout with masonry or concrete, has been made in Gallery No. 2, the depth being 0.50 metre (19.68 inches) and the width 0 * 60 metre (23 * 62 inches) ; and in Tunnel No. 1, in order to provide for the“Great Spring,” theordinary drain has been enlarged from the point where the spring was encountered, 4,400 metres (2.734 miles), to the outlet at Iselle, the size being 0.70 metre (27.56 inches) in width, with a depth of 0.80 metre (31.5 inches). Excavation of the Rock.-The actual commencement of excavation was made by miner’s pick at Brigue on the 1st August, 1898, and at Iselle on the 16th August, 1898, the Brandt drill being started at Brigue on the 22nd November, and at Iselle on the 21st December, 1898. Thesouthern end of thetunnel was 12 miles from the railway, up a steep roadway ; and all appliances and materials had to be brought this distance. Themeeting of the galleries took place on the 24thFebruary, 1905, thus giving a total of 2,392 days. Without making allowance for Sundays,saints’ days, and holidays, norfor those occasions on which work was suspended for verification of the axis, or by accidents or strikes, the average daily advance at eachface was 4.175 metres (13 69 feet), including several months of hand-drilling. Allowing only for the actual days on which the boring-machines worked, the progress was 5-32 metres (17-45 feet) per day at each face, a result never attained on anyother tunnelling work in the world. The Brandt boring-machines used a maximum of 1,000 drills in a day, the number of hand-drills in the same time being 10,000, with a consumption of 760 kilograms (1,675 lbs.) of dynamite, and an output of 450 cubic metres (589 cubic yards) of rock. Up to the dateof the meeting of the galleries, the amount of material excavated was940,000 cubic metres (1,229,500 cubic yards). The number of holes drilled by the machines was 140,000, aggregating in length ZOO kiIometres (124 * 3 miles) ; and the number of holes drilled by hand was 3,600,000, with a consumption of 2,000,000 drills. Thetotal quantity of dynamite usedwas 1,520,000 kilograms (1,496 tons), all of which had to be carried from the

Downloaded by [ UNIVERSITY OF OXFORD] on [13/09/16]. Copyright © ICE Publishing, all rights reserved. 78 FOX ON THE SIMPLON TUNNEL. [Minutes of dynamite-trains upto the working-faces onmen’s backs, with innumerable precautions. The two Tables in Appendix I give typical days’ work : one is satisfactory,with an advance of 10 2 metres (33 *46 feet) in the 24 hours;the second is unsatisfactory, giving a progress of only 4.3 metres (14.10 feet). The following statement of a week’s work, taken haphazard, will give an idea of the progress :- North Side from Brigue. South Side from Iselle. Metres. Feet.Metres. Feet.Metres. 1903, July 12 . . . . 6’80 = 22.30 3.10 = 10.17 ,, ,, 13 . . . . 6.30 = 20.66 4.30 = 14.10 ,, ,, ,, 14 . . . . 6.50 = 21.33 3.70 = 12.14 ,, ,, 15 . . . . 7.30 = 23’95 5.20 = 17.06 ,, ,, 16 . . . . 7.50 = 24.61 6.50 = 21‘33 ,, ,, 17 . . . . 7.20 = 23.62 7.40 = 24.28 ,, ,, 18 . . . . 8.50 = 27‘89 7.30 = 2595 __ -- -- Total. . . 50.10 164.36 37.50 123.03 Pressure of the Roe1c.-In November, 1901, the advanced gallery on theItalian side entered, at 4.422 kilometres (2 748 miles), a formation consisting of calcareous mica-schist entirely decom- posed ; the drills had to be withdrawn, andthe work proceeded by hand. Heavyand close timbering of theentire gallery, on both sides, as well as on roof and floor, had to be done immediately;and although whole timbers were used they were completely crushed, and for thetime the heading was lost. The miners were withdrawn, and a fresh start was made by inserting heavy, rolled steel beams (16 inches deep) bolted together,with balks of pitch-pine 20 inches by 20 inches between them;but the pressure deformed this girder-work,shearing the bolts, and crushing the timber into splinters. As a last resource, the space between the beamswas speedily rammed full of quick-setting concrete, andthis held (Fig. 13, Plate 3). The wagon-road, however, had been maintained, and access was secured for the drill to go on ahead ; and thus the advance, after a delay of 6 months, was resumed. The lining of this portion of the tunnel was a matter of the greatest difficulty ; but at last, after 18 months’ work, at a cost of %1,000 per yard, the permanent tunnel was made secure, being lined withgranite blocks throughoutthe sides, arch, andinvert (Fig. 14, Plate 3). Working Down-Hill from the Brigue Side.--In consequence of the delay caused by the difficulties described above, the Swiss headings had reached the culminatingpoint, 9,573 metres (5 miles 1,670 yards), which had always been arranged to be the extreme boundary

of the workings from that side. In order, however, to save time, it wasdecided todrive forwardas faras possible on aslightly rising gradient, until the top of the future tunnel was reached, by which a point at 9,979 metres (6 miles 350-4 yards) was attained on the 10th October, 1903, or an advance of 407 metres (445 yards) (Fig. 15, Plate 3). It was now impossible to go on further on an upward incline ; and it was decided to drive down-hill, on a gradient of 1 in 40, in order to meet the miners coming up-hill from the Italian end ; and thusthe very problem which the ascending gradientshad been planned to avoid had to befaced (Fig. 15). On insertingan arm intoa bore-hole in therock, the heat was unbearable, the maximum temperature then met withbeing 56' C. (133" F.). As the galleries were driven down-hill, the hot springs followed; and the boring-machines and miners were standing in a sea of hot water. This for a time was pumped out over the apex of the tunnel by centrifugal pumps fixed on travelling carriages ; but at last, at 10,151 metres (6 miles 541 yards), it was found impossible to continue going down-hill. Nevertheless timehad to be saved;and as the height of the finished tunnel would be about 14 feetabove the top of the gallery, it was arranged that the heading should, if possible, be continued ; and to effect this, it was driven on an ascending gradient of 1 in 1,000 (Fig. 15). Meanwhile, strongiron doors were hed in both headings at 10,129 metres (6 miles 517 yards), which could be closed in case of necessity, so asto hold back thehot water. As, however, the actual pressure which would be encountered was unknown, a relief main with necessary valves was provided, which delivered the hot water over the apex of the heading at 9,573 metres (5 miles 1,670 yards). From these iron doors the work was continued under the greatest difficulty, the hot springs in some cases accompanying the miners for a distance of 40 metres (43.74 yards) ; but with great courage and determination, a point at 10,382 metres (6 miles 794 yards) was reached, being a further advance of about 250 metres (273 yards). By means of centrifugal pumps not only was the hot water ejected from the advance heading but cold water was thrown into the fissures, The quantity of hot water amounted to 1,188 gallons per minute, and absorbed 1,350 calories per second, or 65 per cent. of the refrigeration produced. A very hot spring of 528 gallons per minute, encountered on the 18th May, 1904, combined with an accident to the water-conduits outside the tunnel at Morel, compelled the miners to retire, and the work on the north aide ceased. The iron doors were closed, and the portion south of

Downloaded by [ UNIVERSITY OF OXFORD] on [13/09/16]. Copyright © ICE Publishing, all rights reserved. 80 FOX ON THE SIMPLON TUNNEL. [Minutes of them filled with hot water ; but the bottom heading, in virtue of its rising gradient, had become a top heading. By the closing of the iron doors, work in the tunnel on the north side of these doors couldbe proceeded with; and the arching to this point was thus finished. All progress, however, in the advancement of the gallery was arrested ; and it was again prophesied, by those who had failed to realize the determination of the men who had the work in hand, that the tunnel wasnow impossible, and could not be completed. Just before this cessation of work occurred, the engineers on the Brigue side, who were verifying the axis on a Sunday morning when perfect silence reigned inthe solitude of the tunnel, heard the drilling-machines at work on theItalian side, when therestill remained 1,000 metres (1,094 yards) to be perforated. Italian Advance.-All hopes werenow centredon theItalian advance ; but although the miners had the great advantage of an ascending gradient of 7 per 1,000 (1 in 143) to free them from water by gravitation, the temperature and the hotsprings became well nigh unbearable. In Gallery No. 1, which in September, 1904, reached a point (marked E in Fig. 16, Plate 3) 9,141-4 metres (5 miles 1,197 yards) from the portal, a hot spring of 1,400 gallons per minute, at a temperature of 116-6" F., was encountered, and stopped all the work, the air of the headings being 100 * 4" F. A spray of cold water at 50" F. and of 1,056 gallons per minute was established, supplied by pumps at 4400 kilometres (4,812 yards), andthis reduced the temperature to a bearable point, The system, already described, of throwing jets ofcold water intothe fissures from which hot water wasflowing, had also been introduced, and thus a reduced temperature of the water was attained whichwould notinjure the men. The headings, which were in mica-schist, hadto be heavily timbered, andan attack was made in Gallery No. 2, with the object of taking the hot spring in the rear, where fortunately hard limestone was met with which assisted the miners (Figs. 16 and 17, Plate 3). Transverse gallery No. 45 was successfully reached, and a point at 9 183 kilometres (5.706 miles) was attained. The Brandt machine then continued to work on at the advance in Gallery No. 1, while theother two headings, marked D and E, were advanced by hand-labour, one working northward, the other southward, until a junction was effected, which enabled the advance to be pushed forward with great vigour. On the 12th February, 1905, the remaining diaphragm to be pierced was 54.6 metres (59 * 75 yards) ; and on the evening of the 23rd February this had been reduced to 5 metres, or an advance of nearly 50 metres (55 yards) in 11 days, A spring of water of 330

gallons per minuteand 112” F. was encountered on the floor of Gallery No. l from Iselle : at the same time a signal came from Brigue to the effect thatthe gauge on theiron door indicated a reduced pressure onthe imprisoned water;and the necessary arrangements were at once made to allow the escape of the coming 0ood by Gallery No. 2. On the 24th February, at 6 o’clock in the morning, the incoming shift of men, with the officials who intended to assist at the final “ holing through,” were unfortunately delayed by their train being derailed. This was announced by telephone tothe men at work at the face,who at once expressed their willingness to continue their labours. At 7.20 a.m. the final charges were exploded in the roofof the gallery, 9,385 metres from thesouthern portal, producing an aperture 2.6 metres (8.53 feet) in length and 0.80 metre (2.62 feet) in width, Mr. Bacilieri being the only official and engineer actually present. Immediately a large volume of hot water rushed out, which took fr hour to escape. It was necessary for all the men to leave the tunnel, the condition of affairs being much intensified by the stoppage of the engine pumping in cold water. This meeting of the headings at once proved the extreme accuracy with which the works had been executed, but it lacked the fervour and delight usual on such occasions, as in this case it was a meeting of minerson one side and hot wateron the other.The last 245 metres of the gallery had occupied nearly 6 months in execution, owing to the unprecedented difficulties encountered. Creeping of the Floor.-The rising of the floor occurred in several places, even in solid rock, showing the tremendous pressures existing ; and it became necessary to construct masonry inverts for a very considerable distance, which caused much delay. Quarterly &!eports.-It is certainthat such reports as those issued every 3 months have never been given on similar work before;they constitute a complete history of the technical and engineering details, and give the most minute information.The Author would refer members to these reports 1 as illustrating the carewith which every item was considered, and as showing how carefully every particular was registered for guidance and future reference. Appendix I1 is a diary of the progress of the tunnel, as gathered from these reports, twenty-nine innumber. Opening of the Tunnel.-The first train passed through on the 25th January, 1906, and on the19th Map theEing of Italy traversed the tunnel in a special train, meeting the President of

1 A cdmplete set is in the Library of the Institution.-SEC. ISST. C.E. [THE INST. C.E. VOL. CLXVIII.] (f

Downloaded by [ UNIVERSITY OF OXFORD] on [13/09/16]. Copyright © ICE Publishing, all rights reserved. 82 FOX ON THE SIMPLOS TUSSEL. [Minutes of the Swiss Republic at Brigue, who returnedthe compliment by travelling with the King toDomo d'Ossola. On the30th May three long passenger-trains, containing 850 guests, including the Swiss President, Mr. Forrer, andhis Ministers, made the passage of the tunnel, andwere received at all the stations along the route with great respect and rejoicings. On the platform at Brigue there was a Simplon Pass diligence and two snow-sleighs for luggage, with a large placard over them bearing the inscription Morituri te salutnnt. Ventilation and Temperature during trqfiic.-The trains mentioned above were hauled by steam, and as they passed through within 10 minutes of each other the conditions of ventilation could not be expected to be so good as with electric traction, especially as the spraying of the air with high-pressure water was not in operation. The volume of air blown in at Brigue was 169,000 cubic feet per minute, in addition to a further quantity of 50,000 cubic feet per minute forced in at Iselle by Gallery No. 2, and passing outby Tunnel No. 1. Theventilation was excellent, and although the temperature in the middle of the tunnel was high, as is shown by the observations given below, the air was fresh. The train from Brigue to Iselle travelled with the current, and made the passage in 20 minutes, the speed being 36 75 miles per Lour. The temperature of the air outside the tunnel at Brigue \vas 84" F., at 1 kilometre inside the tunnel 82", and at 10 kilometres 87.50, which continued to the southern portal ; whilst the temperature of the air outside at Iselle was 90". Traversing the tunnel in 22 minutes in the opposite direction against the current, and,consequently, meeting the accumulated heated air immediately on entering the tunnel, the results were as follows. The temperature in the open air at Domod'Oasola was SO", inside the tunnel at Iselle 83" F., at 1 kilometre from the south entrance go", at 7 kilometres go", at 10 kilometres 85", at 15 kilometres 75", and at l9 kilometres 65"; whilst outside the tunnel, at Brigue, the temperature was 78". Cost of Tunnel.-Though the cost of the tunnel has not yet been fully ascertained, it is believed to have been about %3,200,000, equivalent to X148 per lineal yard. Debris from the Tunnel.-It is unfortunate that no arrangement was come to between the tunnel-authorities and the Italian government for the debris to be made use of in the construction of the approach-line, for it has been tipped into a large spoil-bank on one side of the valley, while extensive quarries were excavated to supply material for the embankments of the railway. Electric Traction-The tunnel is equipped throughout for electric

traction on the three-phase system with overhead conductors, and the electric locomotives have been at work for some time, Whether from the moisture in the air resulting from the spraying of water, or from other causes, the insulation in two of the motors out of five has, unfortunately,broken down, This is being investigated, and it is expected thatthe electrical haulage of trains willbe resumed shortly. In the meantime the traffic is being satisfactorily worked by steam-locomotives. In conclusion, the Authordesires to draw attention to theexcellent order and neatness which characterized the whole undertaking. Within the boundaries of the installations at both ends of the tunnel no rubbish of any sort was allowed to accumulate. Everything was in its place, and men were constantly employed in sweeping the ground and keeping it clean and tidy. In this respect the undertaking compares favourably with many engineering works in this country ; and it constitutes, from every point of view, an excellent illustration of an engineering project efficiently carried out. In addition tothe names of Dr.Brandau, Dr. Sulzer-Zeigler, Dr. E. Locher-Freuler, Dr. Pressel, Dr. von Kager, and Dr. Rosen- mund, the Authordesires to mention Dr. Haeussler and Mr. Beissner as having been associated with them in the enterprise. The names also of Mr. Colomb, Director of the Federal Railwa.ys, and Mr. Zollinger, Chief Engineer of the Company, will ever remain connected with this great w-ork. The number of men who lost their lives in the execution of the tunnel was sixty;and to them, in May 1905, a monument was erected at Iselie, which it is impossible to read without rendering well-deserved homage to their memory.

The Paper is accompanied by thirteen drawings and tracings, from which Plate 3 and the figures in the text have been prepared.

[APPENDIXES. a2

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...M..*......

.. .h .W... .W.. l- .. .. .H .d. .d..

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SIMPLONTUNNEL. DIARY OF PROGRESS.

Date of Quarterly NO. Yorth B,outh Report. Side Bide from 1eron1 - {rigue. I--l selle. Ietres. M etres. 1 i iIn?tallations commenced on north 1 CO Dec. 31st,1898 333 slde, Aug. 1, 1898. Drillingby , Brandt drill, Nov. 22nd, 1898. 'Installations commenced onsouth 2 ,, Mar. 31st, 1899 470 1 side, Aug. 16, 1898. Drillingby

~ Brandt drill, Dec. 21st, 1898. 3 ,, June30th, ,, 490 331 4 ,, Sept.30th, ,, 544 438 Death of Mr. AlfredBrandt, Nov 5 ,, Dec. 31st, ,, 463 29th, 1899. Appointment of Col. E. Locher. 6 ,, Mar. 31st,1900 470 7 ,, June30th, ,, 482 8 ,, Sept.30th, ,, 483 376

9 ,, Dec. 31st, ,, 384 380~~ 'Permanentventilation commenced 10 ,, Mar. 31st, 1901 574 462 iJMar. 18th. 11 ,, June30th, ,, 502 367 12 ,, Sept.30th, ,, 538 420 The '' Great Spring " struck at 4,400 metres from south entrance, causing great delay ; timbers crushed, girders 13 ,, Dec. 31st, ,, 602 bent ; finally surmounted by filling the spaces withconcrete. Volume of water issuing at south end10,564 gallons per minute. 14 ,, Mar. 31st, 1902 549 15 ,, June30th, ,, 533 16 ,, Sept.30th, ,, 471 575343 l 17 ,, Dec. 31st, ,, 581 49s 1 18 ,, Mar. 31st,1903 462 471 19 ,, June30th, ,, 496 20 ,, Sept.30th, ,, 523 21 ,, Dec. 31st, ,, 194 477-. . 430 'Hot springs and hightemperatures 22 ,, Mar. 31st, 1904 33 encountered at Brigue face. 23 ,, June 30th, ,, 199 537 {l 24 ,, Sept.30th, ,, .. 391 Work suspended at Brigue face. 25 ,, Dec. 31st, ,, .. 52 Hot springs encounteredat southface. Galleries from north and south met, 26 ,, Mar. 1905 .. 191 { Feb. 24th, 1905. Tunnel traversed by Kingof Italy and 27 ,, May 19th, 1906 .. President of the Swiss Republic. Opened byPresident of the Swiss 28 ,, May 30th ,, .. Republic. 29 ,, Junelst, ,, .. Opened for public traffic. - Total length of gallery, 19,729 metres. Total length of tunnel, 19,803 metres.

PRESSURE I ,'