| 摘要 |
<p>A plate (11) shaped as a sector of a circle is graduated in degrees and may be rotated about an horizontal rod (50) with a knurled screw fixing (15). An optical sight (60) in a cradle (21) may be rotated parallel to the plate about an axis (Z) which is orthogonal to the plate and at the centre of the circle. The optical sight assembly includes a measuring arm (23,24) and a vernier scale (25) to read the plate graduations.</p> |
