ALTERNATING MOTORS FOR RAILWAY WORK. 197 
The station generating apparatus has the same cost as be- 
fore. The reducing transformers may be taken at $4000. 
The whole feeder system would be at high tension, and 
there would be no need for raising transformers, since the 
fairly large station generators could well give 5000 volts 
and be overcompounded for, say, ten per cent loss in the 
line. The cost of machines for such voltage might be 
slightly higher, perhaps $rooo on the plant. A like 
amount should be added for high tension switchboard and 
extra appliances. Now the total energy in this case is 
transmitted an average distance of 34,000 ft., as in the 
booster distribution. Using the same formula as in the 
preceding case we have, allowing ten per cent line loss, 
and fifteen per cent extra current to compensate for lag, 
L 4463 X 138 X 1150 
500 
of copper, costing $6312. It is but fair at present to as- 
sume an extra cost of fifty per cent for the car equipments, 
say, $500 per car for fifteen cars, in all $7500. 
We may now gather these data as follows : 
W = 42,078 1bs. 
Cost of Cost of Cost of 1o on 10%on Extra  Sum of 
Case. copper. Extra 2,000,000 copper., extra labor for these 
apparatus. kwh, app. working., anuual 
charges. 
L $24,276 $35.000  $2,427 $37,427 
EE 72,628 ' $ 2,500 30,000 7,262 $ 250 37,512 
EEL 32,288 14,600 30,000 3,228 Y400 $2,560 - 37128 
IV. 6,312 13,500 30,000 635¢ 1,750 31,981 
These figures speak for themselves. In reality IIT is, 
under the assigned conditions, decidedly inferior to the 
others in efficiency, as already indicated. It can only be 
used economically under rather rare conditions, and then 
only in default of a proper alternating motor system. I 
and II are almost exactly epuivalent, and very small differ- 
ences in cost of power generation would throw the advan- 
tage one way or the other. IV is easily the best, and 
would still hold its position of superiority in the face of a 
considerably larger allowance for lagging current than that 
here made. With a smaller permissible loss of energy than 
fifteen per cent, the booster system would drop rapidly to 
%