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 carriage for adjusting the tracer arm holds the metal measuring wheel and vernier. The instrument has no registering dial. A point extending from the back of the carriage allows the user to turn the planimeter vertically and use the other end of the tracer point. Compare to MA*333766.
A wooden case covered with black leather is lined with light blue silk. The top of the case is marked: ME 4P5. A brass plate on top of the case is also marked: 4P5. The number is presumably an inventory number for the Department of Mechanical Engineering at the University of Cincinnati, which donated the object. The instrument resembles the Robertson-Amsler planimeter shown in Hawkins's Indicator Catechism (New York, 1903), 132, and advertised in 1897 as an "averaging planimeter." See MA*302380.01 for instructions.
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. For other planimeters sold by Robertson, see 1994.0356.01, MA*323703, MA*323704, and MA*324247.
References: Advertisement for Robertson-Thompson Indicator, Power 17, no. 2 (February 1897): 25; John Walter, "More Information," The Engine Indicator, Canadian Museum of Making,; 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
Object Name
date made
ca 1900
James L. Robertson & Sons
Physical Description
metal (overall material)
wood (overall material)
leather (overall material)
cloth (overall material)
case: 3.7 cm x 20 cm x 6 cm; 1 15/32 in x 7 7/8 in x 2 3/8 in
place made
United States: New York, New York
ID Number
accession number
catalog number
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of University of Cincinnati Department of Mechanical Engineering
Additional Media

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