r’roccedin,ns.] HOPEINSON ON ELECTRICAL RlILWhYS. 200 14 February, 1593. HARRISON HAYTER, President, in the Chair. (Paper No. NGG.) ‘‘ Electrical Railways : the City and South London Railway.” By EDWARDHOPKISSOX, M.A., D.Sc., M. Inst. C.E. FIVEyears have elapsed since the Author had the honour of describing before the Institution the electrical system of tractios adopted on the Bessbrook and Newry Tramway,’ at that time the only line in the United Kingdom upon which the operation of trains as distinguished from individual tramcars had been carried out electrically. The line has been worked since October, 1885, with perfect regularity,and at accst satisfactory to the pro- prietors. A Table showing the traffic upon it in successive years, and the cost of haulage, is given in the Appendix. In the course of the discussion upon the Paper alludedto, it was shown that the United States were conspicuously in advance of this country in the application of electrical traction to street tramways. At the present time, in almosfi every town in America, horse-traction has been either wholly or in part superseded by electrical traction ; and it was stated,during the last Session of Parliament, in evidence before aJoint Select Committeeof both Houses, appointed to consider theElectric Railway schemes proposed withinthe Netropolis, that in the year 1892, the number of electric tram- ways in the UnitedStates was 436, with 3,532 miles of track, an& 5,851 motor cars, travelling in theaggregate 50,000,000 miles, andcarrying 250,000,000 passengersannually. Although the advance on the Continent has not been so marked as in the United States, still many important city tramwaysystems are now worked electrically. On the other hand, during the past fiveyears, the 8British and Irish electricaltramways, aggregating 22 miles of track, have been reduced by three, on account of the abandon- ment of electrical working on those lines, whilst only 6 new lines havebeen added to the list, making 33& miles of track in all. Such a disparity as this is indeed difficult of explanation. In the use of accumulatorsfor tractive purposes, the experience of all Minutes of Proceedings Inst. C.E., vol. xci. p. 193. [THE INST. C.E. POL. CXII.] P Downloaded by [ Syracuse University] on [13/09/16]. Copyright © ICE Publishing, all rights reserved. 210 HOPEINSON ON ELECTEICAL RAILWAYS. [Minutes of countries has been equally discouraging, and on few of the lines upon whichthe system had been triedhas it come intoper- manent use. Theadvantages of sucha system areuniversally recognized, but repeated and protracted experiments have proved that, with the types of accumulators at present generally avail- able, the cost of maintenanceisprohibitive; and that the several presentwell-known forms of accumulators, whichare doing excellent service in connection with electric lighting, must be greatly improved before they canbe generally adopted for tractive purposes. Many improvements have recently been intro- duced, tending to diminish thedepreciation to which the plates of accumulators are subject when employed under the difficult con- ditions obtaining in tramway work, and there can be no doubt that success will be ultimately achieved. Again, -in conduit systems, IittIe more has been done abroad than in England. The line constructed at Blackpool, in 1886, still remains the onlyone of thattype in England; on theContinent there are but afew examples of the system-the Buda Pesthtramways, which are on an extensive scale and are worked with great success, being the most notable of them ; whilst in the United States,9fr miles of tramway, out of the total of over 4,000 miles worked electrically, are on the conduit system. Probably the considerable first cost of construction is the chief cause of the slow progress made in thisdirection. In theUnited States, electrical traction has become general entirely with overhead systems of conductors, whilst in England exist only the two working examples of the short line at Leeds, comprising 2 miles of double and 15 mile of single line on the Thomson-Houston system, opened for traffic in October, 1891, and the recently-opened line of theSouth Staffordshire Tramways Company, 73 miles inlength. It is generallystated that the reason for overhead systems failing to find a footing in English towns, is the objection on the part of municipal authoritiesto the more or less unsightly erections involved thereby in the streets. Thisexplanation has not been refuted, and no better one has been offered; and it is to some extent substantiated by the fact that, only comparatively recently,Boston, with one of the largest tramway systems in the world, adopted an overheadconductor, whilst Philadelphia and New York are still without this form of electricaltraction on their extensivelines. Theline at Leeds will be useful in testing the realityof this apparently unsatisfac- tory explanation. If, however, in street tramways, Englishpractice has fallen short of American practice, in another directionit has advanced much further than anything that has been attempted Downloaded by [ Syracuse University] on [13/09/16]. Copyright © ICE Publishing, all rights reserved. Proceedings.] HOPKINSOX ON ELECTRICAL RAILWAYS. 211 inother countries. Atthe conclusion of the discussion on his Paper on “the Bessbrook andNewry Tramway,” the Author expressed an opinion that enough had been shown to prove that the system of electrical traction with a continuous conductor was applicableto the great schemes of overhead andunderground railways in our large towns. An opportunity for a practical test soon afterwards presented itself. In the session of 1884, the City of London and Southwark Sub- way Company obtained Parliamentary powers for the construction of a subway from King TYillianl Street in theCity, to the Elephant and Castle in Southwark. Mr. J. H. Greathead was the engineer of the undertaking, and Sir John Fowler and Sir Benjamin Baker were the consul.ting engineers. In pursuance of theoriginal intention, contracts had been arranged for working the lines on the cable system, but the success that hsd attended the Bessbrook and Newry line, and the progress made in electrical traction in the United States and on the Continent, induced Messrs. Mather and Platt, of Rfanchester, to make definite proposals to thedirectors of the Company, for working the line electrically, and to submit designs and estimates. After a most careful investigation of the whole subject, during which various schemes of electrical working were considered, their plan of electrical working was adopted, and a contract wasmade with them in January,1889, for its execution. This contract provided for the supply of 14 locomotives to draw trains consisting of three carriages accommodating 100 passengers, andweighing 44 tons each, and thegenerating-plant was to be sufficient for working aservice of 20 trainsper hour. The contractors further undertook to work the line for a term of two years, or to guarantee the cost of haulage for a similar period, at the option of the Company. In October, 1889, a locomotive, the design of which is described below, was run experimentally on a short section of the line; and a few months later a second loco- motive of a different type was experimented with-the original design being finally adopted. The works were formally opened by H.R.H. the Prince of Wales, accompanied by H.R.H. the late Duke of Clarence, on the 4th of November, 1890; and on the 18th of December, the line was opened for public traffic. It is no part of the Author’s intention to refer to the details of design of the City and South London line, except to such extent as may be necessary to explain the electrical working ; much less to deal with the system of constructing the tunnels, which has made the formation of such a railway possible ; but he proposes to describe as briefly as possible the electrical plant adopted, for the r2 Downloaded by [ Syracuse University] on [13/09/16]. Copyright © ICE Publishing, all rights reserved. 212 HOPUSON ON ELECTRICAL RAILWAYS. [Jfinutes of design of whichhe was responsible, andthe results obtained in working it. The line consists of two independent tunnels,formed of cast-iron rings.The sleepers are transverse, restingdirectly upon these rings,and the rails are spiked thereto, and leave a minimum headway of 9 feet from the rail-level to the highest point of the tunnel. Fig. I, Plate 5, showsa section of the tunnel and the space available. Where the linepasses under the Thames between Great Dover Street and Eing William Street, there is on the up- line o down-gradient of 1 in 30 for a distance of 264 feet, and an up-gradient of 1 in 30 for 462 feet, and on the down line a down-gradient, with the trafic, of 1 in 14, followed by an up- gradient of 1 in 30. Atother points of theline the gradients arenot severe, theprincipal being an up-gradient of l in l00 approaching St.ockwel1 Station.The total length of theline is 3 miles 270 yards. There are four intermediate stations. GENERATOR-STATION,FIG.2, PLATE5. Thegenerator-station is situatedat Stockwell, at a distance of about 500 feet from that terminus. There were originally 6 boilers of Lancashiretype, each 28 feetlong and 7 feetin diameter, fitted with Vicar’s automatic stokers. The boiler-floor is 12 feet ci inches below the ground-level, and the boiler-house is roofed over exceptimmediately above the stoke-hole, so as to provide room for a fuel store. By this arrangement the fuel can be shovelled direct into the hoppers of the stokers. Two similar boilers have subsequently been added. The steam-pressure at the boilers is 140 lbs. per square inch. In addition to prdviding steam for the electric generating-engines, theboilers are requiredfor pro- ducing steam for the powerful hydraulic plant, and the auxiliary engines for the repairing-shop, the compressed-air pumps, and the hauling-engine for drawing the loco~notives and carriages up tllc inclined way connecting the Stockwell terminus with the depdt.