INTERURBAN AND CROSS COUNTRY WORK. 213
must be handled at the extreme end of the section, instead
of the middle point. Since the copper required varies as
the square of the distance, this extreme position would re-
quire four times the copper called for under the original
hypothesis, but on the other hand for this abnormal load
much more than the average drop is allowable.
In this as in all other railway work the real invest-
ment in copper is determined not by the average loss of
energy that may be desirable, but by the maximum drop
permissible under the worst conditions of load. ‘T‘his con-
dition weighs heavily on interurban lines, since where a
network is possible, the various parts of it will not be
loaded simultaneously and can help each other out, while
on a straightaway line each section of conductor must act
for the most part independently.
In spite of this the copper required in the case in hand
is not very formidable. Unless the road is operated on a
regular schedule, still more copper would be required,
since if the operation of the cars is careless and irregular,
more may be massed at a single point than were allowed
for in the estimate. For economy in copper the road must
be intelligently operated as well as skillfully planned. The
same uniform schedule that secures good and regular serv-
ice throughout the line will facilitate good and economical
distribution of power. 'The only reasons for unusual
massing of cars at one point are accidents to the track or
motors or very unusual demands for car service. In the
former case, the service can be resumed on regular time
without any extraordinary demand for power, and in the
latter there will be no trouble if any extra cars that may
be necessary are run in an orderly manner, as they would
be on any well conducted railroad. Managers should bear
in mind that the operators on an important interurban line
should be picked men of more than usual skill and intelli-
gence, and that it pays to get such men. ‘They are worth
the extra cost merely as a form of insurance.
No general rule can be assigned for the increase in
feeder copper due to the demands of heavy displaced loads.
