102 POWER DISTRIBUTION FOR ELECTRIC RATILROADS.
high speeds the author prefers a decidedly heavy trolley
wire and would not hesitate in this case to employ No. ooo
or No. oooo trolley wire, putting the remainder of the cop-
per in two cables of about 450,000 c. m. each.
These feeders may be well arranged as shown in the
dotted lines of Fig. 59, one of them being carried righton
to B the other being tapped into the trolley wire at a few
points, ‘The station A is capable of taking care at the in-
creased voltage on a long stretch of the trolley wire with-
out any taps from the feeder, since a No. oooo wire has
high carrying capacity. ‘Transposing one of our stock
formulee
c.m. E
A5G
and assuming one hundred volts drop, a No. oooo wire can
carry one hundred amperes a distance of over three miles
unaided. ‘T'he main precaution that has to be taken is to
make sure that when a load at B is forcing the boosting
system to its full voltage, a car may not be caught on a
dangerously high voltage near the station. Perhaps the
simplest way of avoiding this contingency is to cut the
trolley wire at some point like*C and feed the section next
the station direct from the generator without the inter-
vention of the booster. If the conductivity of the trolley
wire is needed up to this point for the general transmission
it is easy to reinforce the feeders between A and C by an
equivalent amount. The exact treatment of such a case
must be determined by the relative amounts of true inter-
urban and terminal traffic.
If the problem we have been considering had not in-
volved considerable local work at B, but only interurban
work up to that point, it perhaps would have been better to
operate the line at 1000 volts, using two motors in series.
This procedure would have been feasible if there were, as
often happens, an independent railway system at B. It
probably would not be often desirable to continuea 1000 volt
system through a city for general service, and in the ab-
sence of a substation or a local system there is no good
