Burt's Solar Compass.
Engraving, sheet 140 x 225mm. 5½ x 8¾". Trimmed to platemark top and bottom.
The Solar Compass used to survey lands in Wisconsin, USA, and surrounding areas during the 1840s and 1850s. In 1834, while surveying and subdividing the layout of thirteen townships in land that would one day become northern Wisconsin, government surveyor William Austin Burt of Michigan came to a key realization. High levels of iron ore in the region were disturbing Burt's magnetic compass and garbling readings from the earth's magnetic field, making it difficult to determine north-south survey lines. After a year of experimentation, Burt devised a solution to this problem by inventing a solar compass that did not depend on magnetic readings. It was an innovation that would soon become the standard for surveying in areas with high concentrations of iron ore all over the country. U.S. Army Colonel John Garvin Clark used the compass featured here to survey land in what is known today as Wisconsin, Minnesota, Iowa, and Missouri during the 1840s and 1850s, including the establishment of the Iowa-Missouri line in 1852. Made of brass, the solar compass used by Clark was built in the 1840s by William J. Young, an instrument maker from Philadelphia, Pennsylvania.
[Ref: 9539] £45.00