Mining Instruments are some of the most interesting and collectible surveying instruments ever made. Mine surveying sometimes required looking down a deep shaft. Regular compasses and transits weren't up to the task (the telescope on a transit, for example, could only tilt down so far until the scope would be blocked by the base of the transit). So makers developed specialized instruments that could tilt downward into mine shafts.

Most of the mine surveying instruments involved two telescopes - a regular telescope that could be used for normal surveying operations and a second scope that could tilt down all the way into the mine shaft. Two scope surveying instruments are very cool, super collectible, and fairly rare. Mining transits with only a single scope typically featured significantly included standards, which are pretty rare and super collectible as well.