… oceanographic, hydrological, meteorological or geophysical instruments and appliances, excluding compasses; …
Explanatory notes
… above or below some horizontal reference level; and for all similar measurements in constructional work (building roads, … transits, gyrotheodolites, compass‑clinometers, sighting clinometers for use in survey or artillery, etc. … (to obtain accurate information in respect of the shape, size and co-ordinates of objects in the image or …