338 



NA TURE 



[September 9, 1922 



particularly to the tone and purport of the introductory 

 matter which prefaces the several volumes, and for 

 which they are solely responsible, that exception is 

 chiefly to be taken. 



At the same time there is an element of unconscious 

 humour about the whole production. In view of the 

 hardihood with which they reproduce, for the benefit 

 of German readers, the many strictures on German 

 commercial methods with which they have been visited, 

 one is tempted to suggest that their knowledge of our 

 national literature might have disposed the editors 

 to prefix as a motto on their title-page the lines : 



O wad some power the giftie gie us 

 To see oursels as others see us ! 

 It wad frae monie a blunder free us 

 And foolish notion. 



But possibly these strictures are really considered by 

 them as implying a compliment to what they regard 

 as their business acumen, but what other people are 

 apt to characterise as " slimness." 



Railway Electric Traction. 



Railway Electric Traction. By F. W. Carter. Pp. 

 viii + 412. (London: E. Arnold and Co., 1922.) 

 25s. net. 



THE problems of electric traction on railways 

 deserve special study at the present time. In 

 the past, electrification has been adopted, as a rule-, 

 only when abnormal difficulties, such as the existence 

 of a long tunnel, busy urban traffic, very steep gradients, 

 or a very high price for fuel, had to be overcome. It 

 will be remembered that, largely as the result of a 

 tunnel accident attributed to an accumulation of 

 noxious gases, the New York authorities insisted that 

 practically all lines entering the city should be electri- 

 fied. The underground railways of London, the 

 Simplon tunnel, and the Belt line tunnel of the Balti- 

 more and Ohio Railway, electrified so long ago as 1895, 

 are further examples. The Norfolk and Western 

 Railroad, a heavy goods line, was electrified because 

 of its long and steep gradients. For the same reason 

 the Chicago Milwaukee and St. Paul Railway, which 

 crosses the Rocky Mountains, had to electrify several 

 of its sections. The development of electric railways 

 in Switzerland, in Sweden, in Bavaria, and in Italy 

 is mainly due to the high price of fuel in these countries. 

 It does not follow, however, that electric traction 

 should be used only when special difficulties have to be 

 overcome. When steam operation is a commercial 

 .success, the justification of electrical operation must 

 be that it provides increased transport facilities with 

 NO. 2758, VOL. I lOj 



no increase in the rates. With steam operation in- 

 dividual power generation is employed, whereas with 

 electrical operation the power is developed in bulk at 

 central stations. In the electrical system a break- 

 down at a vital point may stop traffic over a wide area, 

 and to obviate this risk a large amount of capital has 

 to be expended in stand-by plant. In several cases, 

 however, it is more advantageous for the railway to 

 purchase its power from a " bulk supply " station. A 

 disadvantage of a steam locomotive is that it consumes 

 fuel so long as it is in commission ; whether it is inside 

 or outside the shed, and whether it is at rest or in motion. 

 Tube-cleaning, oiling, and overhauling also occupy a 

 considerable time. The electric locomotive, on the 

 other hand, takes power only when running, and the 

 time spent in inspection, overhauling, and cleaning is 

 insignificant. Experience shows that for a given 

 service the number of electric locomotives required is 

 less than half the number of steam locomotives, but 

 to make the comparison fair it has to be remembered 

 that each electric locomotive must be debited with its 

 share of the working costs of the central station. 



The advisory committee of the Ministry of Transport 

 has decided in favour of the direct current system, 

 with a line pressure of 1500 volts, but multiples or 

 submultiples of this pressure may be used. The 

 French, Belgian, and Netherlands governments have 

 come to a like decision. There are, however, thoughtful 

 advocates of single-phase and polyphase systems. 

 Luckily the difference in cost of the various electric 

 systems does not exceed about one, or at the most 

 two, per cent, of the total cost of running the railway. 

 Although from many points of view standardisation 

 of systems is desirable, yet we think that at the present 

 time the carrying out of the single-phase system adopted 

 by the London and Brighton Railway and the direct 

 current system of the North Eastern Railway will be 

 for the benefit of the country. 



In the volume under notice the author gives an 

 excellent discussion of the mechanical and electrical 

 problems which traction engineers have to consider. 

 He points out that the bad riding qualities of a loco- 

 motive are due to one or both of two general causes, 

 namely, the constraint of the wheels to follow other 

 courses than those towards which they naturally tend, 

 and the setting up of resonant oscillations under the 

 control of the springs. The phenomena of "nosing " 

 and " rearing " he ascribes to the former cause, and 

 those of " rolling " and " pitching " to the latter. 



The book can be recommended to the traction 

 engineer, who will find not only a good account of the 

 most modern practice, but also many original dynamical 

 discussions which have a direct bearing on his every- 

 day work. It will well repay study. 



