Peaucellier Straight Line Linkage

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The Peaucellier linkage transforms a rotary input motion into an exact straight line output motion. During the Industrial Revolution, mechanisms for transforming rotary motion into linear motion were an area of intense research. Applications for these mechanisms included guiding pistons of the early steam engines and manufacturing precision parts. The first attempts to solve this problem included Watt's linkage, which only approximates a straight line, and the Sarrus linkage, which does not operate in a single plane. The Peaucellier linkage generates a perfect straight line by geometrically inverting a circular curve. Upon seeing a model of this mechanism, Lord Kelvin is reported to have claimed that "it is the most beautiful thing I have ever seen in my life." A detailed history and explanation of this linkage can be found at: http://en.wikipedia.org/wiki/Peaucellier%E2%80%93Lipkin_linkage