Evans' Grasshopper Linkage - Steam Engine Straight-Line Desk Kit

Oliver Evans, the American steam pioneer, needed a piston rod to move straight in his 1805 Columbian engine, without the heavy guides of the day. His answer was the grasshopper beam: a long swinging leg holds one end of a short beam, a crank holds its middle, and the far end moves up and down in a near-straight line. The leggy look gave the engine its name. Slide the red knob and it follows its short straight groove in the walnut-style base, while the long rocker leg swings far below. Engraved…

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