Lyman Protracting Trigonometer Signed Crane & Vinton

Josiah Lyman (1811–1889) patented this device on May 25, 1858 (no. 20,356) and made additional improvement no. 280 on May 15, 1860. A semicircular German silver protractor pivots on a thin metal arm (61 cm or 24 inches long) that resembles the base of a T-square. The arm is heavily tarnished. The protractor is divided by half-degrees and marked by tens from 20° to 90° to 20° and from 70° to 0° to 70°, both in the clockwise direction. The protractor is also marked for compass headings: W (at 20°), N (at 90°), E (at 20°). The protractor is slightly tarnished, and the number 30 is scratched near the 30° mark on the left side of the protractor. A vernier on the inside edge of the protractor, attached to the long arm, permits angle readings to one minute of arc. The number 89 is stamped on the front side of the housing for the screw that tightens the vernier from the back of the protractor.

There is another screw at the right side of the protractor base. The base is marked: PATENTED BY J. LYMAN. (/) MAY 25, 1858. (/) CRANE. &. VINTON. (/) MAKERS. BRATTLEBORO. VT. According to the patent, the long arm should be marked with scales—these scales are what make the instrument a trigonometer. However, this particular object is not so marked. The number 79 is stamped above the pivot on the back of the protractor. The trigonometer is stored in a fitted butternut case. The case is marked ACPL 1848 (/) 11-3-TOP, presumably to indicate the location of item number 1848 in the Amherst College Physics Laboratory, the donor of the instrument.

Lucius H. Crane (1807–1877) and John F. Vinton (1834–1889), machinists of Brattleboro, Vt., manufactured 100 protracting trigonometers for Lyman. Edwin Putnam, who worked in Crane's shop, probably made the ruling markings. Vinton's father, Timothy (1803–1889), was a prominent American paper manufacturer. Vinton served as a lieutenant in the 16th Vermont Volunteers during the Civil War. Despite testimonials from prominent professors and government surveyors, the upheavals of the war apparently prevented this device from finding a market. A 22-inch, German silver protracting trigonometer like this one was priced at $35.00 in 1862. See also 2009.0244.01.

References: Josiah Lyman, "Protractor" (U.S. Patent 20,356 filed May 25, 1858), "Drafting Plotters" (U.S. Patent 38,904 filed June 16, 1863), and "Protracting Trigonometers" (U.S. Patent 149,590 filed April 14, 1874); Peggy A. Kidwell, "Josiah Lyman's Protracting Trigonometer," Rittenhouse 3 (1988): 11–14; Robert C. Miller, "A Lyman Protracting Trigonometer Made by Heller & Brightly," Rittenhouse 3 (1989): 129–131; Walton's Vermont Register, Farmer's Almanac, and Business Directory for 1875 (Claremont, N.H., 1875), 99; Mary Rogers Cabot, Annals of Brattleboro, 2 vol. (Brattleboro, Vt.: E. L. Hildreth & Co., 1922), i:450, ii:641; "Timothy Vinton," The American Stationer 27 (1890): 80; Josiah Lyman, A Manual of the Protracting Trigonometer (New York: Sheldon & Co., 1862), v.

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