Object Details
- Description
- In the late 19th century, American draftsmen experimented with different designs for making protractors more versatile. For instance, the secretive machinist Samuel Darling, who operated a separate partnership with Joseph R. Brown and Lucian Sharpe of Providence, R.I., between 1866 and 1892, patented a "bevel and protractor" on July 19, 1887. This was a nearly circular protractor with an extended arm that slid along and rotated around a ruler.
- Alton J. Shaw, who apprenticed in the main firm of Brown & Sharpe, came up with a design that was less cumbersome than Darling's. Although Shaw filed for a patent one month before Darling did, Shaw's patent was not granted until August 2, 1887. His protractor consisted of a circle with an extending arm, cut from sheet steel, which fit on a groove within a three-sided square, also cut from sheet steel. An advantage of this protractor was its reversibility. Shaw assigned his patent to Darling, Brown, & Sharpe on August 19 in exchange for $75. The firm marketed the protractor for $6.50, or for $7.75 with a case. In its catalogs, Brown & Sharpe adopted the British spelling, "draughtsmen's".
- This instrument is an example of Shaw's design. The protractor is divided by single degrees and marked by fives from 0 to 90 in the clockwise direction. Thirty more unnumbered divisions extend past the 90° mark. A vernier on the frame allows angles to be measured to one minute of arc. The interior of the protractor is marked: Darling, Brown & Sharpe. (/) Providence. R.I. (/) Pat. Aug. 2. 1887. The protractor is in a wood and morocco leather case that is lined with purple velvet. The case has broken apart into at least three pieces. A worn instruction sheet (ID number MA.336072.1.1), dated August 1889, is stored with the object. The instructions indicate that a guiding lever, which was placed in two of the eleven holes at the top of the protracting circle, is missing from the object.
- Shaw later moved to Milwaukee, Wis., and then to Muskegon, Mich., where he established the Shaw Electric Crane Company. The company became Lift-Tech International in 1986. The Brown & Sharpe Mfg. Co. absorbed Darling, Brown & Sharpe in 1892. After over a century as one of the largest American machining firms, Brown & Sharpe ceased manufacturing machine tools and drawing instruments in 1991. The firm now manufactures optical measuring instruments as a subsidiary of Hexagon Metrology.
- This protractor was owned by the renowned American designer of steam engines, Erasmus Darwin Leavitt Jr. (1836–1916), and donated by his granddaughter, Margaret van D. Rice.
- See also ID number 1990.0317.02.
- References: Oscar James Beale, Practical Treatise on Gearing (Providence, R.I.: Brown & Sharpe Mfg. Co., 1886), 73-75; Samuel Darling, "Bevel and Protractor" (U.S. Patent 366,651 issued July 19, 1887); Alton J. Shaw, "Protractor" (U.S. Patent 367,673 issued August 2, 1887); Amy Ackerberg-Hastings, "The Brown & Sharpe Draftsmen's Protractor," Rittenhouse 15, no. 1 (2001): 31–38; Henry Dexter Sharpe, A Measure of Perfection: The History of Brown & Sharpe (North Kingston, R.I.: Brown & Sharpe, 1949), http://www.roseantiquetools.com/id44.html.
- Location
- Currently not on view
- Data Source
- National Museum of American History
- inventor
- Darling, Samuel
- maker
- Darling, Brown & Sharpe
- date made
- 1889-1892
- patent date
- 1887
- Credit Line
- Gift of Margaret van D. Rice
- Physical Description
- velvet (overall material)
- morocco leather (overall material)
- sheet steel (overall material)
- Measurements
- overall: 2 cm x 27.2 cm x 17 cm; 25/32 in x 10 23/32 in x 6 11/16 in
- Object Name
- protractor
