Amsler Type 6 Polar Planimeter Sold by Crosby Steam Gage & Valve Co.

This German silver instrument has a 6-1/2" pole arm and an adjustable 10" tracer arm with white celluloid measuring wheel, vernier, and registering dial. The tracer arm is marked for the following settings: 19.568/100 [square] cm, 19.632/0.1 [square] f[oot], 21.245/10 [square] inches. The pole arm is marked in script: Crosby Steam Gage & Valve C^o Swiss Manufacture. Underneath the pole arm is a serial number: 39707. Part of the serial number is repeated underneath the tracer arm near the point: 707. The pole weight is missing.

A wooden case covered with black leather is lined with black velvet. The top of the case is marked: CROSBY STEAM GAGE & VALVE Co. BOSTON. (/) Swiss Manufacture. A handwritten paper label is pasted inside the lid: PRICK POINTS ON PLANIMETER WHEN (/) SET FOR LENGTH OF CARD, GIVE MEAN (/) EFFECTIVE PRESSURE DIRECT FOR (/) 40 SCALE. The label also has a table of factors, from 10 = 1/4 to 100 = 2-1/2.

This is a Type 6 polar planimeter from the workshop founded by Jacob Amsler in Schaffhausen, Switzerland, in 1854. Using the serial number, planimeter scholar Joachim Fischer dated the instrument to about 1910. The Crosby Steam Gage & Valve Company made pressure gauges, indicators, and other equipment related to steam engines in Charlestown, Mass., from 1875 to the 1940s. To measure the diagrams produced by its indicators, Crosby imported and offered Amsler planimeters. This model sold as No. 3 and cost $30.00 from 1888 to 1907 and $42.00 sometime after 1907. See 1999.0250.02 for instructions. On Crosby and planimeters, see also 318485.

The instrument was received at the museum in 1975.

References: Joachim Fischer to Peggy A. Kidwell, October 19, 1992, Mathematics Collection files, National Museum of American History; Crosby Steam Gage & Valve Co. Catalogue (Boston, 1888), 104–109; Crosby Steam Gage & Valve Co. Catalogue (Boston, 1900), 170–176; Crosby Steam Gage & Valve Co. Catalogue (Boston, 1907), 203–210; Crosby Steam Gage & Valve Company, Practical Instructions Relating to the Construction and Use of the Steam Engine Indicator (Boston, 1911), 43–46, 83–86; Crosby Steam Gage & Valve Company, Catalogue 32: Indicators and Appliances (Boston, n.d.), 8; Craig Bliss, The Crosby Steam Gage & Valve Co., http://www.crosby-steam.com/index.htm.

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