Navigation

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.

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.
Description
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.
Location
Currently not on view
date made
ca 1894-1936
ID Number
MA.333663
accession number
300659
catalog number
333663
To determine where one is going, it is necessary to know where one is currently located. Beginning in the 17th century, navigators combined multiple triangulations to ascertain the position of their ships.
Description
To determine where one is going, it is necessary to know where one is currently located. Beginning in the 17th century, navigators combined multiple triangulations to ascertain the position of their ships. With a sextant and a station pointer, sailors in the 19th century could plot locations from three data points as long as they were within view of land.
Navigators employed a sextant to measure the angles between their position and each of three known landmarks. They then placed the station pointer on their chart and set its arms to the observed angles. The center of the protracting circle on the station pointer would then show the position of the ship. Station pointers were also useful for surveying the geographical features of coastlines, either from the water or on land, in order to create accurate maps.
This station pointer consists of a brass circular protractor divided by single degrees and marked by tens from 0° to 180° to 0°. Three black-coated anodized brass arms meet in the open center, which has a brass pricker for positioning on the chart. Three brass and blackened anodized brass legs are screwed to the center piece by rings on one end of each arm. Each leg has a thumb screw for tightening in position and an arrow for pointing to the angle measurement. The number 602 is engraved near the top of the center leg.
The rectangular wooden case has wood built-ins and green fabric lining to support and cushion the instrument. The case is fastened with two brass hooks. It is cracked in the left front corner, and there are several dirt and paint marks. This station pointer was probably mainly used for charting a ship's position, since it lacks the verniers that were typically found on the arms of station pointers employed in surveying.
Ursula N. Forbes donated the instrument in 1986.
Compare this station pointer to ID Number MA.333663.
References: National Maritime Museum, "Charting Instruments—Station Pointer," http://www.nmm.ac.uk/collections/search/listResults.cfm?name=Station%20pointer&category=90488; William John Macquorn Rankine, A Manual of Civil Engineering, 5th ed. (London, 1867), 120–121.
Location
Currently not on view
date made
20th century
ID Number
1986.0316.07
accession number
1986.0316
catalog number
1986.0316.07
This clear Perspex (acrylic glass) square protractor is divided by single degrees and marked by tens in the clockwise direction from 010° to 350°. A red arrow points to the origin. The marks for 090°, 180°, and 270° are replaced by the compass points E, S, and W, respectively.
Description
This clear Perspex (acrylic glass) square protractor is divided by single degrees and marked by tens in the clockwise direction from 010° to 350°. A red arrow points to the origin. The marks for 090°, 180°, and 270° are replaced by the compass points E, S, and W, respectively. Diagonal lines to the four corners of the protractor are marked with the compass points NE, SE, SW, and NW. A pinhole is at the center of the protractor.
The interior of the protractor is marked with a grid. Tick marks (four per square) appear along the X and Y axes and around the outside edge of the grid. The top is labeled (in red): MACLEAN PROTRACTOR. Maker's marks are at the bottom: REGD. TRADE MK. AIRNAVA; J. D. MACLEAN ∙ Co. LONDON W.C.2. The protractor is stored in a tan cardboard case, which is printed with instructions for using the instrument. Marine and aviation navigators could employ it as a parallel rule, station pointer, and plotter. John Donald Maclean patented a rectangular protractor and parallel rule in the United States. No record of a trademark for "Airnava" was found in the United States or in Great Britain. This form of protractor is standard and is sometimes called a Douglas type of square protractor. Weems & Plath manufactures similar protractors in the 21st century.
Reference: Journal of Navigation 15, no. 4 (1962): front matter.
Location
Currently not on view
date made
1950s-1960s
maker
J. D. Maclean Co.
ID Number
1987.0788.05
accession number
1987.0788
catalog number
1987.0788.05
This white plastic circular protractor is mounted on a clear plastic square plotting board with green grid lines. The board bears a white arc for correcting against compass errors of VARIATION, divided to single degrees and marked by tens from 30 to 0 to 30.
Description
This white plastic circular protractor is mounted on a clear plastic square plotting board with green grid lines. The board bears a white arc for correcting against compass errors of VARIATION, divided to single degrees and marked by tens from 30 to 0 to 30. The letters E and W are printed above the 25° points. The protractor is divided by single degrees and marked by tens from 0° to 350°. A compass rose, with an arrow at North and the letters E, S, and W inside triangles, appears inside the degree circle.
An extending arm is affixed to the center of the protractor. The end of the arm on the protractor is marked with +2 (in black), +4 (in green), and +1 (in black). The arm also bears an arc for correcting against compass errors of DEVIATION, divided by single degrees and marked by tens from 20 to 0 to 20. The letters E and W are printed above the 15° points.
The part of the arm that extends for 9-3/4" beyond the protractor is divided by tenths and labeled for NAUT[ICAL] MILES. Markings by ones from 1 to 5 are for a scale of 1:40,000 n.m.; markings by ones (in green) from 1 to 10 are for a scale of 1:80,000 n.m.; and markings by ones from 1 to 2 are for a scale of 1:20,000 n.m. The arm is marked with instructions for use: Set 0 on compass circle to variation on square base. Align arm with course. Align cross lines on base with any meridian or parallel on chart so arrow on base points north. Read compass course on compass circle opposite deviation on arm. Deviation may be marked inside compass circle.
A sheet of instructions is also provided with the instrument and its clear plastic sheath. The arm is marked with the object's name—DE LUXE COURSE PROTRACTOR (/) PAT. PENDING—the Danforth/White company logo—the letters DW with the slogan, THE MARK OF SAFETY AFLOAT—and the maker's mark: DANFORTH/WHITE (/) PORTLAND, MAINE (/) ©1959, by R. S. Danforth. Felsenthal Instruments Co. manufactured this protractor for Danforth/White, which made well-regarded nautical compasses in the 1960s. Since the 1980s, the company has sold weather stations and instruments under the name Maximum Inc. For Felsenthal, this protractor was product number FDD-7.
See also 1977.1141.01, 1977.1141.02, 1977.1141.03, 1977.1141.05, 1977.1141.08, 1977.1141.09, 1977.1141.10, 1977.1141.11, 1977.1141.12, 1977.1141.18, 1977.1141.19, 1977.1141.20, 1977.1141.21, 1977.1141.22, 1977.1141.23, 1977.1141.24, and 1977.1141.30.
Location
Currently not on view
date attributed by donor
1969
maker
Felsenthal
ID Number
1977.1141.39
accession number
1977.1141
catalog number
336423

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