As noted in the Introduction, the earliest use of protractors was probably in navigation. Protractors assisted with laying out angles to indicate the actual or desired direction of a ship. Makers might have also marked protractors with additional scales to be employed in computing a ship’s speed or direction, such as rhumbs or seconds. When coastal surveying projects were conducted in the 19th century, navigators used substantial protracting instruments called station pointers both to ascertain their position along a coastline and to record the topographical measurements of that coastline. In the 20th century, protractors were also utilized in aviation navigation.
"Protractors - Navigation" showing 1 items.
- This station pointer was designed for surveying coastlines. It consists of a brass circular protractor with a German silver inlay that is divided to half-degrees and marked by tens from 0° to 350°. Five brass arms meet around the open center. Three of the brass arms are screwed to German silver legs (1/2" wide and 14-1/2" long). The two outer legs are movable and have verniers that permit readings to one minute of accuracy. Each vernier is adjusted with two thumbscrews. Three additional German silver legs in the case may be attached to each leg with thumbscrews. This extends to 27" the leg length. The legs and extensions are matched with numbers (1, 2, 3) engraved near the end of each leg and on the top back of each extension.
- The rectangular hardwood case also contains two brass center pieces. One has a glass bottom for viewing the center point, and the other is a solid cylinder with a thumbscrew on the top and a pinpoint on the bottom for accurately marking the center point. The case is fastened with two metal hooks and lined with black velvet. A nameplate on the case is engraved: U. OF MO. (/) 1804. The number is probably an item number assigned by the manufacturer or by the Department of Civil Engineering at the University of Missouri-Columbia, which previously owned the instrument.
- There is otherwise no maker's mark, but the station pointer resembles instruments advertised by Keuffel & Esser (K&E) between 1906 and 1936 and by Dietzgen between 1902 and 1921. K&E indicated it had copyrighted and begun to sell its station pointer in 1894 at the behest of the U.S. Navy. This design may have pre-dated 1894, as it is shown (without magnifying glass) in William Ford Stanley, Mathematical Drawing and Measuring Instruments, 6th ed. (London, 1888), 268–269. K&E offered a smaller and coarser station pointer in its 1890 catalog.
- The magnifying glass depicted in the K&E and Dietzgen advertisements is not present on this station pointer, but there is a casing for the screw which would have held the magnifying glass near the center of the protractor. However, the K&E and Dietzgen station pointers were both described as being numbered in both directions, while the protractor on this station pointer is numbered only once. K&E sold its station pointer for $90.00 ($160.00 with the case).
- The instrument is probably older than station pointer 1986.0316.07.
- References: J. A. Bennett and Olivia Brown, The Compleat Surveyor (Whipple Museum, 1982), 24; Catalogue and Price List of Eugene Dietzgen Co., 6th ed. (Chicago, 1902), 161; Catalogue and Price List of Eugene Dietzgen Co., 11th ed. (Chicago, 1921), 106; Catalogue of Keuffel & Esser Co., 21st ed. (New York, 1890), 110; Catalogue of Keuffel & Esser Co., 32nd ed. (New York, 1906), 180; Catalogue of Keuffel & Esser Co., 38th ed. (New York, 1936), 196.
- Currently not on view
- date made
- ca 1894-1936
- ID Number
- accession number
- catalog number
- Data Source
- National Museum of American History, Kenneth E. Behring Center