SWITCHBACK  , a

form of pleasure railway, built over alternate descents and ascents, the train or car first gathering momentum by running down an incline, and surmounting by means of this a lesser ascent . Switchbacks were originally merely an imitation, using cars upon wheels, of the sledge-coasting courses of Russia, and were indeed named by the French montagnes russes . They were introduced in Paris in 1816, but soon disappeared in con-sequence of several serious accidents . About 188o they again became popular both in Europe and America . A variation of the switchback, though lacking its essential principle of climbing by means of momentum, is the water-chute, an imitation of the Canadian toboggan-slide, in which cars built in the shape of boats glide down steep inclines into artificial lakes at their bases . This is popularly called " shooting the chutes." A further variation is " looping the loop," in which a heavy car on wheels, or a bicycle, starting at a considerable altitude, descends an incline so steep that sufficient momentum is accumulated to carry it completely round a track in the form of a perpendicular loop, in the course of which journey the occupants or rider, while crossing the top of the loop, are actually head downwards . Later it was made even more dangerous by taking out part of the top of the loop, so that the car or bicycle actually passes through the air across the gap .