Solar Compass

Solar Compass

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William J. Young mentioned this instrument in a letter that he sent to the inventor, William A. Burt, on June 14, 1848: "On the 21st of April I sent to Mr. John Ferris of Pauline, Dutchess Co. N.Y. one Solar Compass." A Ferris descendant gave it to the Smithsonian. The horizontal circle is silvered, graduated to 30 minutes, and read by opposite verniers. A telescope is mounted at one side of the compass, and a counterweight is mounted on the other. With the telescope is a vertical circle that is graduated to 30 minutes, and read by vernier to single minutes. The inscriptions read: "Burts Patent" and "Made by Wm. J. Young Philada."
A solar compass is a railroad compass with a solar attachment that allows surveyors to find north by reference to the sun rather than by reference to the magnetic needle. The form originated with William Austin Burt, a United States Deputy Surveyor who began surveying government lands in Michigan in 1833. In 1835, while working in an area of Wisconsin where there were large deposits of iron ore, Burt experienced great difficulty in using his standard vernier compass. By December he had roughed out his ideas for a solar compass, and asked William J. Young to make a model that he could submit to the Patent Office. Burt received a patent (#9428) the following year, and the Franklin Institute awarded him the Scott’s Medal for this "ingenious" instrument. But, as the solar compass was not yet serviceable, Burt went back to the drawing board. In 1840, confident that he had solved all the problems of his design, Burt asked Young to produce solar compasses. In 1850, the year that Burt’s patent expired, the General Land Office adopted the solar compass as a standard instrument for all major boundary lines in regions of magnetic disturbance, and demand rose accordingly. Claiming that he had never received even $300 "for his right in said invention," Burt petitioned Congress to renew his patent, but to no avail.
Burt’s solar apparatus has three arcs: one for setting the latitude of the land to be surveyed; one for setting the declination of the sun; and one for setting the hour of the day. In the latter half of the 19th century, several instrument makers offered solar attachments of this sort that could be used with transit instruments.
Ref: William A. Burt, Description of the Solar Compass (Detroit, 1844).
William A. Burt, A Key to the Solar Compass, and Surveyor’s Companion (Philadelphia, 1855).
John Burt, History of the Solar Compass Invented by Wm. A. Burt (Detroit, 1878).
Currently not on view
Object Name
Solar Compass
Young, William J.
Burt, William A.
place made
United States: Pennsylvania, Philadelphia
overall: 9 in; 22.86 cm
telescope: 12 in; 30.48 cm
vertical circle: 4 in; 10.16 cm
overall in case: 7 3/8 in x 15 1/4 in x 9 7/8 in; 18.7325 cm x 38.735 cm x 25.0825 cm
ID Number
accession number
catalog number
Credit Line
Conrad S. Ham
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Surveying and Geodesy
Data Source
National Museum of American History
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