FUNDAMENTAI, PRINCIPLES. 27 
power at some distant part of the system. Such shifting 
of the load occurs in nearly all cases of linear distribution, 
and has already been noted, but it also occurs on all sorts 
of systems, and is the more serious as it is less to be regu- 
larly expected. A single blockade may fill a limited dis- 
trict with stalled cars, and when at last it is broken the call 
for power is of a most abnormal kind. It does not appear 
strongly marked on the load line, but shows in the shifting 
of load from one feeder to another. On systems of moderate 
size this shifting of load may be very serious. Forexample, 
through the baseball season many roads will find nearly 
their full output demanded at the ball park once or twice 
a week. The next maximum output may be at the other 
end of the system, to accommodate some special celebration. 
FEven in a large network, at certain hours, during, and just 
before, maximum load, the bulk of the load will be within 
a small district, and within the same district only when the 
same causes produce the shifting. 
This wandering of the main load over the system 
is one of the most exasperating factors in the design of the 
conductors. It may easily amount to the concentration of a 
quarter or third of the total load at some quite unexpected 
point. It can be dealt with only by a minute study of the 
local conditions, which generally will furnish some clue to 
the probable magnitude and position of such wandering 
loads. Whatever may be the general conditions of drop, 
the conductors must be so distributed as to prevent the sys- 
tem breaking down when loaded in some abnormal man- 
ner at some unusual point. No theory can take account 
of such occurrences; their ill effects can be obviated only 
by good judgment, which is of more value than many 
theories.