seems as if the engineer settles down to his real work with a sigh of
relief when the limits of the city have been passed; for in the towns
there are many signals to be watched, many crossings to be looked out
for, and a multitude of moving trains, snorting engines, and tooting
whistles to distract one's attention. The "runner," however, seemed not
to mind it at all. He pulled on his cap a little more firmly, and, after
glancing at his watch, reached out for the throttle handle. A very
little pull satisfied him, and though the increase in speed was hardly
perceptible, the more rapid exhaust told the story of faster movement.
As the train sped on, the engineer moved the reversing-lever notch by
notch nearer the centre of the guide. This adjusted the "link-motion"
mechanism, which is operated by the driving-axle, and cut off the steam
entering the cylinders in such a way that it expanded more fully and
economically, thus saving fuel without loss of power.

When a station was reached, when a "caution" signal was displayed, or
whenever any one of the hundred or more things occurred that might
require a stop or a slow-down, the engineer closed down the throttle and
very gradually opened the air-brake valve that admitted compressed air
to the brake-cylinders, not only on the locomotive but on all the cars.
The speed of the train slackened steadily but without jar, until the
power of the compressed air clamped the brake-shoes on the wheels so
tightly that they were practically locked and the train was stopped. By
means of the air-brake the engineer had almost entire control of the
train. The pump that compresses the air is on the engine, and keeps the
pressure in the car and locomotive reservoirs automatically up to the
required standard.

Each stage of every trip of a train not a freight is carefully charted,
and the engineer is provided with a time-table that shows where his