FAST AND HEAVY RAILWAY SERVICE. 235 
A.M. during which period six trains would be in service 
on each half of the line. Of these the outgoing trains 
would be nearly empty, but on the other hand all the in- 
going trains would be crowded, and one or two of them 
would carry an extra car. We must, therefore, allow for 
extra load, and a fair assumption would be to consider all 
the trains as three-car trains well loaded. 'This means not 
far from 120 k. w. per train, about 1440 k. w. for the full 
output of the station. 
The working voltage should be as high as feasible. 
Without any radical innovations it is quite practicable to 
allow a normal voltage of 600 at the motors. ’T'his should 
not be much exceeded, while the pressure may without 
trouble be allowed to fall ten per cent below this at the 
termini during heavy loads. Let us first examine the ter- 
minal conditions. Two trains will ordinarily be handled 
in that region, requiring by our assumption 240 k. w. To 
allow for rapid acceleration of a heavy train, fully this 
amount of power may be temporarily required, but two 
trains will not have to start together. If, following Fig.119, 
we allow 500 amperes available at the terminus we shall be 
safe so far as this point is concerned. 
As to drop, if we take ten per cent as average during 
the busy hours we shall not go far wrong, allowing twenty 
per cent at the termini during heavy loads. Even a little 
more would be safe if occasion demanded, so that if the 
dynamos gave about 600 volts overcompounded about ten 
per cent, say, to 670, the minimum pressure could be safely 
taken down 150 volts to 520. We must then have at the 
termini enough feeder capacity to give 500 amperes with- 
out dropping the voltage below 520. 
Now for such a road as we are considering the track 
should be first class, rails not less than eighty pounds per 
yard, and most carefully bonded. Four lines of eighty 
pound rails give an equivalent conductivity of about 5,120, - 
ooo c. m. Assuming that the bonding lowers the con- 
ductivity one-third, the track is equivalent to about 
3,400,000 c. m. of copper. In spite of this the heavy