Escalator
In 1859, the first U.S. patent for an escalator-type idea - titled "Revolving Stairs" - was issued to Nathan Ames, of Saugus, Mass. (No. 25,076). He arranged steps on an inclined, endless belt placed around rollers, so when placed in motion, the steps act as elevators saving muscular effort. When stationary, the stairs could be used in the usual way, but when in motion, a person could also walk up the steps and so ascend with increased speed. The patent showed not only two parallel sets of stairs (one up, one down), but also a triangular arrangement whereby the same endless belt would provide upward movement on one inclined plane to the apex, and from there downward motion on the second inclined plane.«