Robertson-Amsler Polar Planimeter

This chrome-plated instrument has a 5" pole arm with a small cylindrical weight at the end. The 7" tracer arm is adjustable and has an L-shaped tracer point, so that the point is offset from the arm. The measuring wheel is chrome and the vernier is brass. The instrument has no registering dial. A point extending from the carriage holding the measuring wheel allows the user to turn the planimeter vertically and use the other end of the tracer point. Compare to 1981.0301.01.

Most of the leather has flaked off of the wooden case, which has green fabric on the bottom. The case is lined with burgundy velvet. The instrument resembles the Robertson-Amsler planimeter shown in Hawkins's Indicator Catechism (New York, 1903), 132. A worn instruction card (MA.302380.01) received with the object in 1972 describes it as an "averaging planimeter," which is how Robertson advertised the instrument in 1897.

Hine & Robertson of New York City made steam-engine indicators and sold planimeters from the 1880s to 1897. The firm was then renamed James L. Robertson & Sons and remained in operation until at least 1910. This device is smaller than the Hine-Robertson planimeter described by Olaus Henrici.

The instrument was received at the Museum in 1972.

References: Advertisement for Robertson-Thompson Indicator, Power 17, no. 2 (February 1897): 25; John Walter, "More Information," The Engine Indicator, Canadian Museum of Making, http://www.archivingindustry.com/Indicator/sourceinfo.htm; Olaus Henrici, "On Planimeters," in Report of the Sixty-fourth Meeting of the British Association for the Advancement of Science (London, 1894), 515–516; "Hine and Robertson's Planimeter," The Electrician 26 (February 6, 1891): 432.

Currently not on view