The fireman on a fast locomotive is kept extremely busy, for he must
keep the steam-pressure up to the required standard--150 or 200
pounds--no matter how fast the sucking cylinders may draw it out. He
kept his eyes on the steam-gage most of the time, and the minute the
quivering finger began to drop, showing reduced pressure, he opened the
door to the glowing furnace and fed the fire. The steam-cylinders act on
the boiler a good deal as a lung-tester acts on a human being; the
cylinders draw out the steam from the boiler, requiring a roaring fire
to make the vapour rapidly enough and keep up the pressure.

Though the engineer seemed to be taking it easily enough with his hand
resting lightly on the reversing-lever, his body at rest, the fireman
was kept on the jump. If he was not shovelling coal he was looking ahead
for signals (for many roads require him to verify the engineer), or
adjusting the valves that admitted steam to the train-pipes and heated
the cars, or else, noticing that the water in the boiler was getting
low--and this is one of his greatest responsibilities, which, however,
the engineer sometimes shares--he turned on the steam in the injector,
which forced the water against the pressure into the boiler. All these
things he has to do repeatedly even on a short run.

The engineer--or "runner," as he is called by his fellows--has much to
do also, and has infinitely greater responsibility. On him depends the
safety and the comfort of the passengers to a large degree; he must
nurse his engine to produce the greatest speed at the least cost of
coal, and he must round the curves, climb the grades, and make the
slow-downs and stops so gradually that the passengers will not be
disturbed.

To the outsider who rides in a locomotive-cab for the first time it