A rare 4th quarter 19th century 4-vane American mining circumferentor, signed by engraved script on the silvered compass face, "A. S. Aloe, Makers, No 2461 St Louis", with 4.25" needle, 7.5" exterior graduated limb, and four 5" tall sighting vanes.

A.S. Aloe was one of few Midwest makers and retailers of scientific and mathematical instruments. They seem to have assimilated some of the instrument designs of Blattner & Adam also of St. Louis, sometime early in the 4th quarter of the 19th century. This 4 sight vane circumferentor has a railroad, or improved motion, which was popular to engineers. This design was made specifically for mining (and is advertised as such); it was built in a compact and rugged form with only a 30" tall tripod (all original to the instrument). As exploration tunnels in underground mining were very small, mining surveyors typically had to survey on their hands and knees.

This compass was used in a coal mine and shows it. The tripod and case are black with coal residue, the instrument shows the hardships of it's use as well; while it is complete, it is well worn on the exterior, as is the case, which protected the instruments while the surveyors crawled through the exploration tunnels. The primary instrument operator must have assembled the instrument in the pitch black at times; there are little notches filed in the vanes and side of the limb in order to differentiate parts by feel, an interesting feature. Although worn, I believe all these characteristics enhance this compass as they truly relate its past use and the typical conditions of a 19th century underground mining surveys. A rare American mining outfit for the serious collector.

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