FAST AND HEAVY RAILWAY SERVICE. 249 
track gives nearly the equivalent of a perfectly grounded 
circuit. 
Let us assume a line one hundred miles long connect- 
ing two cities, and six trains in regular service. Using 
transformers on the motor cars the whole transmission 
problem works out in a singularly simple manner. Using 
12 as our track constant and taking 10,000 volts as 
terminal voltage with 2000 volts extreme drop, a single 
power station in the middle of the line would do the work 
very easily. Applying our usual formula for 1000 k. w. 
delivered 
Y2 100 968 600 
i T 
Hence a No. ooo wire over each track would do the work 
easily with not more than 714 per cent average drop. The 
total amount of copper would then be about 270 tons, cost- 
ing, say, $75,000. The transformer capacity should beat a 
maximum about 1000 k. w. per train, normally not over 
8oo k. w. 'This would add a weight of not over eight to 
ten tons, which can easily be spared from the 140 allowed 
for. 
The copper for a polyphase system would probably be 
in excess of that just figured, but would not vary materi- 
ally for the purpose in hand. 
If the distribution were effected by delivering power 
to transformers along the line the cost of the conducting 
system would evidently be much increased, tor the primary 
feeding line could not be decreased while retaining the same 
loss and the secondary working line would have to be of at 
€1, = 159,000. 
least the same size to carry the necessary working current. 
For the same total loss the cost of copper would be more 
than doubled, and the transformer capacity when distrib- 
uted along the line would also have to be nearly or quite 
doubled. In point of total cost there is no comparison be- 
tween the systems, and it is likely that the maintenance 
of the former would also be considerably less, thus giving a 
double advantage. Speaking broadly, omne may at the 
present time say with certainty, that a maintained speed of