. The American railway; its construction, development, management, and appliances . are believed to bethe steepest grades worked by ordinary locomotives on smoothrails. Another American invention is the switchback. By this plan USES OF THE SWITCHBACK. 9 the length of line required to ease the gradient is obtained by run-ning backward and forward in a zigzag course, instead of goingstraight up the mountain. As a full stop has to be made at theend of every piece of line, there is no danger of the train runningaway from its brakes. This device was first used among the hillsof Pennsylvania over fo
. The American railway; its construction, development, management, and appliances . are believed to bethe steepest grades worked by ordinary locomotives on smoothrails. Another American invention is the switchback. By this plan USES OF THE SWITCHBACK. 9 the length of line required to ease the gradient is obtained by run-ning backward and forward in a zigzag course, instead of goingstraight up the mountain. As a full stop has to be made at theend of every piece of line, there is no danger of the train runningaway from its brakes. This device was first used among the hillsof Pennsylvania over forty years ago, to lower coal cars down intothe Nesquehoning Valley. It was afterwards used on the Callao,Lima, and Oroya Railroad in Peru, by American engineers, withextraordinary daring and skill. It was employed to carry thetemporary tracks of the Cascade Division of the Northern PacificRailroad over the Stampede Pass, with grades of 297 feet permile, while a tunnel 9,850 feet long was being driven through themountains. With the improvement of brakes and more reliable means of. A Switchback. stopping trains upon steep grades, came a farther development ofthe above device, which was first applied on the Denver and RioGrande Railroad in Colorado, and has since been applied on agrand scale on the Saint Gothard road, the Black Forest railwaysof Germany, and the Semmering line in the Tyrol. This device isto connect the two lines of the zigzag by a curve at the point lO THE BUILDING OF A RAILWAY. where they come together, so that the train, instead of going al-ternately backward and forward, now runs continuously on. Itbecomes possible for the line to return above itself in spiral form,sometimes crossing over the lower level by a tunnel, and some-times by a bridge. A notable instance of this kind of location isseen on the Tehachapi Pass of the Southern Pacific, where the line ascends 2,674feet in 25 miles,with eleven tun-nels, and a spi-ral 3,800 feet PLAN. SfLVDlPlUMI
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