As the train gathered speed the engineer pulled the throttle open wider and wider, the puffs in the short, stubby stack grew more and more frequent, and the rattle and roar of the iron horse increased.

Down in the pit of the engine-cab the fireman, a great shovel in his hands, stood ready to feed the ravenous fires.  Every minute or two he pulled the chain and yanked the furnace door open to throw in the coal, shutting the door again after each shovelful, to keep the fire hot.

[Illustration:  “FIRING” A FAST LOCOMOTIVE An operation that is practically continuous during a fast trip.]

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 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