Then the "piano box"--electro-pneumatic--was installed; 150 feet of levers was reduced to 30 feet of small handles hardly larger than faucet handles and quite as easily turned. The control of a great terminal was brought down to three towermen, acting under the direction of their chief, the shirt-sleeved keeper of the city gate. "We've got to keep them hustling," he tells you. "There's the morning express in from New York. She's heavy this morning. That train over there, coming across the swing-bridge, is the millionaire's special. She's all club-cars, comes in every mornin' from the seaside. Her wheels'll stop on the same nick as the express. Watch them both, carefully." "Isn't it quite a trick handling those trains simultaneously?" "Not much," a smile fixed itself upon the chief towerman's features, as he fingered his greasy timetable. "Here's four trains pulling out here simultaneously at 5:40. On top of that we get a Forest Hills local in at 5:39, a Hudson Upper local at 5:40, an Ogontz at 5:42, a Readville at 5:43, all incoming, and pull out two more at 5:43. Ten trains in just four minutes isn't bad, and we haven't begun to feel the capacity of this terminal yet. "That isn't all of it. We get the whole thing criss-crossed on us sometimes; and perhaps they'll put on an extra getting out of here at 5:40, and that'll bother us a little, for we have regular tracks assigned for all our scheduled trains. If they don't run in the extras on us, or we don't get a breakdown anywhere, it's pretty plain sailing. Ring off your 10:10, Jimmy." Jimmy, the assistant at the far end of the tower, touched one of the little handles, a blade on a signal bridge opposite the end of the train-shed dropped, a big locomotive caught the rails instantly and cautiously led a long train of heavy cars out through the intricacy of tracks and switches until it was past the tower, over the "throat" of the yard, and, striking on the main line, was gaining speed once more. "It's as easy for him as unbroken rail off in the country," said the chief towerman to me, as he waved salutation at the engineer passing below him. Then he fell into a detailed and wondrous explanation of the intricacies of the "piano-box" mechanism. On the lower floor of the tower were air condensers, and through the medium of electricity and compressed air heavy switches and signals a half-mile off are worked almost by finger touch. Each switch is guarded by at least one signal, possibly two--home and distant--and these blades show an open or a closed path to the engineer. They are so arranged that normally they stand at danger and in case of breakdown they return by gravity to danger. At night the blades, which in various positions show safety and danger and caution, are replaced by lights--red for danger, yellow for caution, green for safety--according to the present standard rules. * * * * *