DIRECT FEEDING SYSTEMS. 79 
Obviously a maximum load at B will produce no 
trouble, so that we may pass to the section B D. If this 
be fed in the middle at & the loss in the trolley wire at 
average load is very trifling, not more than that due to the 
current for two cars over each trolley wire at a distance of 
3000 ft.—about nine volts. So far then as average loss is 
concerned we could properly allot to the feeder carrying 
ninety amperes a loss of forty-one volts.- If BD and A B 
are connected at B we can get considerable relief in ordi- 
nary states of load. The worst possible load would be 300 
amperes at B and 250 at D. ‘The drop in B D would then 
be thirty-six volts. Since with such a compound load the 
overcompounding would be up to its full amount, we can 
allow eighty to ninety volts loss between & and the station. 
If this were all in the feeder H 4, it would have to be of 
about 288,000 c. m. But onaccount of the overcompound- 
ing we can get material aid from the main line up to B, 
and so will try to make a No. oooo (211,000 c. m.) answer 
the purpose. If the line via B can be counted on for, say, 
seventy amperes, the No. oooo will take the rest. With 
370 amperes the drop from H to B is about 40 - 45 volts 
in H ¢4 and B & respectively, less the over compounding, 
while the loss in B & would be nominal. In fact a glance 
at these figures shows that a No. ooo will do admirably, for 
our line via B can evidently furnish considerably more than 
seventy amperes without too much loss. 
This settles the first two sections. As to the third, it 
is evident at a glance that it cannot be fed in the middle 
point since A B with two trolley wires could not be so fed, 
while C E has only one. Therefore a feeder should be run 
by the shortest route from the station to. CE and then 
along the line to E, for 300 amperes is too much to carry 
over a No. oo trolley wire, and that load must be dealt with 
at E. Let H ¢ be this feeder, 8ooo ft. long, 4000 ft. being 
along the line. Now if we could depend on stiff overcom- 
pounding to help us out at E, these feeders could be quite 
moderate in size. As it is however the chances are that 
the load on other parts of the system would be rather small