Precision clinometer with spirit-level for measuring angle of plane to horizontal

摘要

The instrument has a frame (1) with a plane base (2) supporting the protractor (4) which has a spirit-level (6) aligned with the zero of its scale (7). The spirit-level is carried by an inverted-T tube (5) with a lens (12) at the top of its upright (11) for visual enlargement of the bubble. The optical axis (10) of the lens is perpendicular to the spirit-level and passes between its reference marks. The protractor is rotated by means of a screw (15) in mesh with a ring of teeth (17) on the back of the protractor near its rim.