Trough Compass

Size : stander

origin  : India

The trough compass is  used for marking the magnetic north line on the drawing sheet of the plane table. In this case, the magnetic needle point to 0° – 0° of the graduated scale and a line drawn parallel to the edge of the trough compass is along the magnetic meridian.

This trough compass is placed on the plane table to help in aligning the table accurately with north-south and east-west directions. Surveyors use it to sight distant objects with known azimuths, aiding in orienting the plane table precisely.