184 REPORT 1861, 



mankind. Consef[uently at no former period of the world's liistory liave the sub- 

 jects to which this Section is devoted assumed such magnitude and importance as 

 they now do. And those wlio devote themselves to these subjects may rest assured 

 that they labour iu a field which is practically without limits, and in a soil tliat 

 can suffer neither from exhaustion nor over-cultivation. Tliey who have lived 

 through the last thirty years have witnessed triumplis of ingenuity far surpassing 

 those of the past, but which, in like manner, may be surpassed by the future. I 

 am proud to belong to this Section, and deem it an honour to be called upon to 

 preside over its sittings on this occasion. The papers read here treat of subjects 

 which, from their nature, cannot be amongst the most popular, but they ai-e second 

 to none in utility. One of the objects of the British Association is to encourage 

 and stimulate scientific pursuits ; and stimulus is sometimes wanted even to the 

 working qualities of Englishmen. We must take care not to fall behind other 

 countries. We cannot forget that for some years we have had to go to Prussia for 

 the steel tiers of our locomotive engines, and that lately we have had occasion to 

 seek locomotive boiler-plates in France. It is plain we cannot rest in our wonted 

 superiority, and slacken and gi-ow idle. Even in Russia it is now proposed to put 

 up works for the manufacture of steel with machinery, which is intended to surpass 

 our own. We shall not, however, unless we become supine, suffer from the 

 advancement and improvement of other countries, and the British Association is 

 large enough in its sympathies to take pleasm-e in the advancement of science and 

 art in every part of the globe. 



On tJie Poiuer required to overcome tJie Vis Inertice of Railway Trains, with 

 a Description of a Machine to propel Trains between Stations at frequent 

 Intervals withont Locomotives. Bj Peter W. Barlow, C.E., F.R.S., F.6.S. 



The attention of the author was first directed to this subject on the opening of 

 the North Kent Railway, in 1850, when the loconrotive engineer reported that a 

 much larger consumption of coke ensued than on the main line of the South-eastern 

 Railway with similar trains. Upon iu^-estigation of the cause of this diflference, 

 by experiments on the atmospheric railway and on locomotive trains, it became 

 apparent that the increase arose from the power required to overcome the vis inertice 

 of trains, more frequently occun-ing from the greater number of stations. The 

 remedy then applied by his advice was locomotives of more tractive power, thus, 

 however, adding to the weight of the engine and to destruction of the permanent 

 way. The tractive power has been gradually increased with increased traffic to 

 such an extent that in some instances tlie author recently observed that a speed of 

 twenty miles is now frequently reached before the last carriage leaves the platform — 

 a speed which would cany the train above half a mile by its own momentum or 

 vis viva ; and it then occurred to him tliat if by a local tractive power, applied 

 during the length of the platform, a velocity of thirty- four or thirty-five miles 

 could be given, railways ha^'ing frequent stations could he worked by stationary 

 power, at a small comparative cost, and the e^ils of locomotives (particularly in 

 underground railways) could be avoided. The author explained, by experiments, 

 that the economy of stationary power arose not only from its usual economy over 

 locomotives, but that, by the law of accelerating forces, a train that wo\dd be pro- 

 pelled at a given velocity for a given distance would be propelled at a much greater 

 velocity by four times the power applied one-fourth of the distance. The pro- 

 pelling power suggested to be employed is that on Mr. Armstrong's hydraulic 

 principle ; and the author estimates that a tractive force of 8 tons (equal to that 

 of three locomotives) applied for 300 feet at a station will propel a train of 60 tons 

 for one mile at gi-eater velocity than if one locomotive worked the whole distance. 

 It was also explained that such mode of applying stationarj' power would not 

 interfere with the use of locomotives for special purposes ; and that although sucli 

 propellers as the author advocated were especially adapted to lines having frequent 

 trains, yet they would be very valuable on railways generally, particulaiiy at sta- 

 tions at the foot of inclines, where at present much time is frequently lost in getting 

 hea'S'y trains into motion. 



