It was not by any means the first time that Allan West had sat watching this fascinating scene, but it had never grown uninteresting and he had never ceased to wonder at it. “I used to think train-dispatching was a pretty nerve-racking business,” he remarked, after a while, “but it’s child’s play compared with this.” “Well, I don’t know,” said Jim, his eyes on a through train threading its way cautiously out of the terminal and over the network of switches. “We don’t have to worry about big accidents up here—the interlocking takes care of that. We can’t have a head-end collision, for instance—at least, not while the signals are working properly. What we’ve got to look out for is tangles. If we have to hold one train two or three minutes, that means that two or three other trains will be held up, and before you know it, you’ve got a block ten miles long. Then’s when somebody up here has to do some tall thinking and do it quick. The only way to keep things straight is to keep ’em moving. Sixteen,” he added to his assistants, as the overhead bell rang. They watched the train as it rolled in, saw it disgorge its load of passengers, saw the baggage and express and mail matter hustled off, saw the yard-engine back up and couple on to the rear coach, and slowly drag the train out from under the train-shed. “I never watch that done,” added Jim, as the train disappeared down the yards, “but what my heart gets right up in my throat. You don’t know what a way those pesky little yard-engines have of jumping switches. Open sixteen, Sam,” he added, as the big engine which had brought the train in rolled sedately down the yards on the way to the round-house, to be washed out and raked down and coaled up. “Ring off thirteen, Nick,” he said, and Nick touches one of the little handles, a blade on a signal bridge opposite the end of the train-shed drops, there is a sharp puff, puff, of a locomotive, and another train starts slowly from the train-shed on its journey east or west, north or south, as the case may be. Meanwhile, the little switch-engine has set its train of coaches in upon one of the innumerable sidings away down the yards where passenger cars are stored—and one would scarcely believe how many miles of such storage track every great terminal requires—has uncoupled and started back toward the train-shed for another load—her movements, by the way, as well-known to and thoroughly understood by the chief towerman as are those of the most glittering through train. Already the train of coaches is in the hands of the cleaners and stockers, for it will start out again presently upon another trip. Modern passenger cars represent too much money to be allowed to repose on a siding a minute longer than necessary.