surveying compass

Datecirca 1860

Inventory Number0204b

ClassificationMagnetic Compass

Subject

Maker Thomas Hall fl. 1840 - 1875

Cultural Region

Place of Origin

Dimensions4 x 13.8 x 14 cm (1 9/16 x 5 7/16 x 5 1/2 in.)

Material

DescriptionThis is a type of surveying compass that can be suspended from a wire or line by means of hooks on top of the sights. It is similar to a miner's compass, but does not have the compass set in gimbals or a built in clinometer. The sights are missing from this example. (See 1997-1-1865 for a complete compass by the same maker.)

It has an octagonal brass frame set into an oak base. The wind rose is silvered and has a bilevel scale. It has 8 points marked with initials, and a circle divided for azimuth from 0°-360° by single degrees. The compass needle has a jeweled pivot. The needle brake is missing.

SignedHall. Boston.

Historical AttributesThis magnetic compass was used with a tangent galvanometer, which was likely made by Thomas Hall of Boston. The galvanometer has a platform on which the user my place whatever magnetic device he wishes.