56 Mr. Edward Hopkinson [Feb. 24, 



permitting a more frequent service. We cannot expect, therefore 

 that electric traction with our present knowledge will take the place 

 of steam traction on our trunk lines ; but it has its proper function 

 in the working of the underground lines now projected for London, 

 Paris, Berlin, Brussels, and other large towns, and also I think on 

 other urban lines, for example, on the Liverpool Overhead Eailway, 

 where trains of large carrying capacity are not required, but a 

 frequent service is essential ; and finally, also on those short 

 lines, whether independent or branches of the great trunk lines, 

 where water-power is available. When I undertook the construction 

 of the Bessbrook line it was a condition that the cost of working 

 should be less than the cost of working by steam, a condition which 

 the first six months of working showed to be successfully fulfilled. 

 When Messrs. Mather and Piatt undertook the construction of the 

 electric plant for the City and South London Eailway, they guaran- 

 teed that the cost of traction for a service of 8247 miles per week as 

 actually run should not exceed 6 ■ 3d. per train mile, exclusive of the 

 drivers' wages. Their anticipations have been more than realised, 

 the actual cost being 5 -Id per train mile only. There are, 

 however, other projects, both in America and on the Continent, for 

 electric railways on which the special feature is to be an enormously 

 high speed of travel, speeds of 150 and even 200 miles per hour 

 being promised. With a steam locomotive, involving the recipro- 

 cating motion of the piston and connecting rod, such speeds are 

 probably unattainable, but they may be realised in the purely rotary 

 motion of an electric motor. But at such high speeds as these the 

 power required to overcome the air resistance is of special considera- 

 tion. Probably up to speeds of 750 miles per hour, or even to 

 higher limits still, the ordinary law of air resistance holds good, as 

 the rate of disturbance is still less than the velocity of waves in air, 

 but above these limits we leave the regions of ordinary locomotion 

 and enter rather into the field of projectiles. Assuming, however, 

 that the ordinary laws of air resistance do hold good, I calculate that 

 the power required to propel an ordinary train 200 feet long at 

 200 miles per hour against the resistance of air alone, apart from the 

 frictional resistances, would not be less than 1700 horse-power. 

 Though there is nothing to prevent the construction of electric 

 locomotives capable of developing this or even greater power, the 

 strength of the materials at present at command will set a limit to 

 the speeds which may be obtained. 



In order that the engineer may realise the imperfection of all his 

 works, it is well for him to be constrained from time to time to con- 

 template the amount of energy involved in his final purpose compared 

 with the energy of the coal with which he starts. I have endea- 

 voured to put before you to-night the losses that occur and the reasons 

 for them, in some steps of the complex machine which constitutes an 

 electric railway ; so in conclusion I will draw your attention to the 

 ultimate efficiency of the machine, starting with the coal and ending 



