We turn from the car-service men back into a department that is strictly traffic. Coal service is one of the principal sources of income for this particular railroad. It stretches some of its branches into bituminous fields, and others through the anthracite fields that Nature, in some freakish mood, implanted in just a few counties of Northeastern Pennsylvania. That entire country is comparable to a cut of beef, the coal veins resembling streaks of fat that run hither and thither. As in beef, the lean predominates. The fat streaks are the valuable coal veins, the lean the earth, slate and rock in which the coal was planted during some great convulsion of Nature in the process of the creation of the world. How it got into this particular spot science cannot tell. What it is, further than the fact that it is mostly carbon, science only guesses. It guesses that it was originally bituminous coal and that by some process of intense squeezing in an upheaval of Nature, the oil and tar and gas of the bituminous coal was squeezed out and the much more valuable anthracite deposits created. Mining consists in getting the streaks of fat anthracite out of the bulk of lean earth and rock. The veins run well down into the mountains, and, as do the little streaks of fat, lose themselves in the rock, or lean, to continue the simile. Some of the veins are but a few feet in thickness, while some run to as high as twenty and thirty feet, and, as a rule, the farther down into the earth they go the better the coal; and the farther down you go the more difficult and expensive is the mining. Now, here is a traffic that demands and receives special attention. In other days the mining of anthracite coal was, itself, merely a department of operating for the half-dozen systems that stretched their rails into that valuable Pennsylvania corner. That work has now been removed into the control of separate mining companies; but the handling of coal is a great function of not only these roads, but of the systems that reach their tendrils into the valuable bituminous fields here and there about the country. [Illustration: THE GREAT BRIDGE OF THE NEW YORK CENTRAL AT WATKINS GLEN] [Illustration: BUILDING THE WONDERFUL BRIDGE OF THE IDAHO & WASHINGTON NORTHERN OVER THE PEND OREILLE RIVER, WASHINGTON]