Before the engineer can run his train, the way must be cleared for him,
and when the train starts out it becomes part of a vast system. Each
part of this intricate system is affected by every other part, so each
train must run according to schedule or disarrange the entire plan.

[Illustration: TRACK TANK]

Each train has its right-of-way over certain other trains, and the
fastest train has the right-of-way over all others. If, for any reason,
the fastest train is late, all others that might be in the way must wait
till the flyer has passed. When anything of this sort occurs the whole
plan has to be changed, and all trains have to be run on a new schedule
that must be made up on the moment.

The ideal train schedules, or those by which the systems are regularly
governed, are charted out beforehand on a ruled sheet, as a ship's
course is charted on a voyage, in the main office of the railroad. Each
engineer and conductor is provided with a printed copy in the form of a
table giving the time of departure and arrival at the different points.
When the trains run on time it is all very simple, and the work of the
despatcher, the man who keeps track of the trains, is easy. When,
however, the system is disarranged by the failure of a train to keep to
its schedule, the despatcher's work becomes most difficult. From long
training the despatchers become perfectly familiar with every detail of
the sections of road under their control, the position of every switch,
each station, all curves, bridges, grades, and crossings. When a train
is delayed and the system spoiled, it is the despatcher's duty to make
up another one on the spot, and arrange by telegrams, which are repeated
for fear of mistakes, for the holding of this train and the movement of