Amsler Type 2 Polar Planimeter

This German silver instrument has a 6-1/2" arm with tracer point and 6-1/2" pole arm. The arm lengths are fixed. The tracer arm and pole arm are connected by a hinge and form a circle around the white plastic measuring wheel, vernier, and registering dial when the instrument is closed. The pole weight is missing. The top of the tracer arm is marked in script: J. Amsler. A serial number is marked underneath the tracer arm and the weight: 67925.

A wooden case is covered with black leather. The corner of a label attached to the bottom of the case is missing. The remaining part reads: SA ROSENHAIN (/) S. Bento, 60 – S. Paulo (/) [illegible] 2. 260$. The symbol has two vertical lines to denote the Brazilian real. The distributor was probably Casa Rosenhain, an importer operated by a German firm, Schmidt & Company, and located adjacent to the Rua São Bento park in São Paulo in the early 20th century. The donor, Sebastian J. Tralongo (1928–2007), served in the U.S. Navy during World War II and then worked for the Vitro Corporation in Rockville, Md., for 35 years. He patented a device for signaling from deeply submerged submarines and assigned the rights to Vitro. He did not report how he came to own a planimeter sold in Brazil.

This instrument is in the design invented by Jacob Amsler (1823–1912) and made by the workshop he founded in Switzerland. The material, rounded hinge, and presence of a registering dial indicate this is a Type 2 of the six versions manufactured by Amsler.(Around 1910 Amsler's firm added a registering dial to the Type 1, but began to make that version from brass instead of German silver.) The serial number and the signature, which the firm began to use after Amsler's death, indicate that this planimeter is significantly younger than MA.318485. Unlike that instrument, the arms on this object are equal in length. Planimeter expert Joachim Fischer dated this object to about 1925. For more information on Amsler, see 1987.0107.10.

According to the accession file, this instrument was received at the Smithsonian in 1984,

References: "Enemy Trading List Issued by the War Trade Board," Official [U.S.] Bulletin 1, no. 176 (December 5, 1917): 11; "Tralongo, Sebastian James 'Subby'," Hartford Courant, May 26, 2007; Sebastian J. Tralongo, "Submarine Signal Device" (U.S. Patent 2,989,024 issued June 20, 1961); "Vitro Corp. – Company Profile," http://www.referenceforbusiness.com/history2/25/Vitro-Corp.html; Crosby Steam Gage & Valve Co. Catalogue (Boston, 1888), 104–109; Joachim Fischer to Peggy A. Kidwell, October 19, 1992, Mathematics Collection files, National Museum of American History.

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