A plane table compass, sometimes referred to as a trough compass, used by surveyors and artillery crew to accurately establish magnetic north.
The compass is precision machined of brass material with a long needle to ensure accuracy. The compass scale is marked with a centre zero (for magnetic north) and graduations indicating plus and minus five degrees. The compass is housed in a protective wooden case with a sliding lid. The lid has a brass slide which locks the compass needle during periods when the compass is not in use.
The compass is precision machined of brass material with a long needle to ensure accuracy. The compass scale is marked with a centre zero (for magnetic north) and graduations indicating plus and minus five degrees. The compass is housed in a protective wooden case with a sliding lid. The lid has a brass slide which locks the compass needle during periods when the compass is not in use.