Protractors - Surveying
Since the first protractors appeared near the turn of the 17th century, around the same time that the technique of triangulation was developed for surveying, their utility for this activity appeared evident from early on. Surveyors typically carried at least one protractor in their field kits. The instrument might be combined with another drawing instrument, such as a set of parallel rules. By the 19th century, makers tried to blend convenience with multi-functionality, offering rectangular protractors that fit easily in a case or pocket and that were packed with aids for reducing real-world distances to proportional scales. They also showed off their improving craftsmanship with fine objects that retained accuracy in measurement. (See also the page on Engineering & Drafting.)
"Protractors - Surveying" showing 1 items.
- This brass circular protractor was manufactured in the mid-19th century and made available for sale by the New York City firm headed by Benjamin Pike (1777–1863). Pike, a dealer of optical, mathematical, and philosophical instruments whose firm serviced the entire United States, partnered at various times with his sons, Benjamin Jr., Daniel, and Gardner. The business was called “Benjamin Pike & Son,” as is marked on the vernier limb of this protractor, between 1831 and 1841 and between 1843 and 1850.
- This protractor likely would have been of interest to surveyors and engineers. The object is divided by single degrees. It bears two sets of markings by tens in the clockwise direction: from 0° to 90° to 0° to 90° to 0°, and from 10° to 360°. Brass arms extend into the center to divide the protractor into quadrants. The arms are not placed at the 0° and 90° points, as one might expect, but rather at the 50/50, 40/140, 50/230, and 40/320 markings. There are rounded, beveled notches at the 90/90 and 90/270 markings. A round hole (5/8" diameter) is at the center. Crosshairs would typically have been placed in this hole to mark the origin point for measuring angles, but no crosshairs are present. Instead, a brass piece fills about one-third of the hole.
- An arm pivoted from the center carries a vernier, which allows the user to read off angles to 10 minutes of arc. The vernier is marked by 30s from 60 to 0 to 60. The vernier arm is marked: Benj-n Pike & Son New York. The arm extends beyond the vernier. A brass strip, fastened on top of the arm, contains a sharp metal pin that pokes through a hole near the end of the arm. The pin was used to prick, or mark, angle points.
- This protractor has some notable differences from the circular protractor depicted in Pike catalogs of 1848 and 1856: its outer edge is smooth instead of appearing to bear gear teeth; it has one vernier arm instead of two; and it has two sets of markings instead of one.
- References: Deborah J. Warner, “Browse by Maker: Pike,” National Museum of American History Physical Sciences Collection: Surveying and Geodesy, http://americanhistory.si.edu/collections/surveying/maker.cfm?makerid=22; Benjamin Pike Jr., Pike’s Illustrated Descriptive Catalogue of Optical, Mathematical, and Philosophical Instruments (New York, 1848), 43–45; Benjamin Pike Jr., Pike’s Illustrated Descriptive Catalogue of Optical, Mathematical, and Philosophical Instruments (New York, 1856), 43–45; facsimile with historical introduction by Deborah J. Warner (Dracut, Mass., and San Francisco, 1984).
- Currently not on view
- date made
- Pike, Jr., Benjamin
- ID Number
- accession number
- catalog number
- Data Source
- National Museum of American History, Kenneth E. Behring Center