Vannevar Bush's Profile Tracer

This experimental instrument for land surveying consists of a mechanism in a wooden box that is suspended between two wooden wheels with rubber tires. The wheels are aligned as in a bicycle, with the box in between. There is a roll of paper mounted on top of the box. If one runs the wheels over a surface, the combined action of a servo-mechanism and an integrator produce a profile of the land traversed which is plotted on the paper. The engineer Vannevar Bush received a patent for this instrument in 1912, and it was the subject of the master's degree dissertation he wrote at Tufts University the next year. Servo-mechanisms, integrators, and the graphical display of results played a major role in several computing instruments Bush later designed. He also is remembered for ideas about information retrieval that inspired later thinkers to develop what is now called hypertext.

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