… surveying), hydrographic, oceanographic, hydrological, meteorological or geophysical instruments and appliances, …
Explanatory notes
… or artillery, etc. (2) Optical levels (spirit, autoset, telescopic, collimator, laser, etc.), generally used mounted on a tripod. (3) Alidades (whether or not with a telescope), optical squares and cross‑staffs (whether or not … errors in perspective, etc., due to variations in the terrain. (2) Restitution apparatus (stereoplotting …