The caller tells the engineer and fireman to report at the roundhouse at 5:45 A. M. At that hour the hostlers have made the 1847 fit for service. Her tender has been filled with coal, her tanks with water, even her sand is packed aboard the box that stands upon the boiler and is ready to help on slippery rail and upgrade. The engineer makes keen inspection of the 1847 before he moves her a single inch, makes sure with his keen and practised eye that she is quite fit for service, pokes here and there and everywhere with his long-spouted oil-can. At a minute or two after shop whistles have shrieked "six o'clock" he pulls the 1847 out from the shadows of the roundhouse. He gets an open signal and switch to the main yard and finds waiting on a siding in that great place, the trail of freight cars and the caboose that are going with him to make Third-118. Now come back for a moment in your thought. While we were still scurrying down to the grimy yard, the despatcher was creating Third-118. On his desk were car reports, showing what had been received and sent out, and there was enough accumulation of stuff in the yards last night to justify a Third-118. Because good railroading means yard-sidings cleared, and standing cars and freight, like passengers, kept constantly moving, he did not hesitate at ordering her out. He found that there would be 32 cars between tender and caboose, weighing approximately some 1200 tons, and so he ordered from the roundhouse an engine of a class which the mechanical department guaranteed capable of pulling from 1,000 to 1,500 tons, gross weight. [Illustration: _Courtesy of the "Railroad Age Gazette"_ THE ELECTRO-PNEUMATIC SIGNAL-BOX IN THE CONTROL TOWER OF A MODERN TERMINAL] [Illustration: THE RESPONSIBLE MEN WHO STAND AT THE SWITCH-TOWER OF A MODERN TERMINAL: A LARGE TOWER OF THE "MANUAL" TYPE] [Illustration: "WHEN WINTER COMES UPON THE LINES THE SUPERINTENDENT WILL HAVE FULL USE FOR EVERY ONE OF HIS WITS"] [Illustration: WATCHFUL SIGNALS GUARDING THE MAIN LINE OF A BUSY RAILROAD] The yardmaster had given the numbers of the cars that were to make Third-118, just as he received them from one of the despatcher's assistants, to a switching foreman, who arranged them, with the quick facility that comes from long practice, into an order that would permit them to be set off at various points up the line, with the least possible amount of switching. That practical sequence worked out in pencil and paper, a stubby switch-engine effected in reality. The cars and the caboose, in proper order, were ready, with the crew, and inspected when the 1847 backed to them and Third-118 came into her being.