Page:Popular Science Monthly Volume 37.djvu/398

384 much more lightly and hence much more cheaply than if stiff rails were used. On curves, sidings, and sections for loading and unloading, however, it is found better to employ the stiff rails, which are supported by posts thirteen feet apart. The form of



switch which has been devised for telpher lines consists of a hinged stiff blade of steel, which allows a train to run off on to a stiff siding, when it is lowered so as to rest on the main line.

At intervals along the line straining-posts are placed, each of which acts as an abutment for a number of spans on one side, and carries a compensation gear, by which an equal number of spans