All Cassens & Plath sextants are equipped with a vernier, which enables a reading accuracy of one tenth of a degree or minute. The following example explains how to read the sextant's vernier correctly (larger images can be opened on the right side):
0° position | |
1° position after an exact 360° turn of the vernier | |
Example for 0°39,7' | |
The upper line (with a dot) of the right-hand scale indicates the whole minute of the left scale. In this example 39'. The decimal value is read from the right-hand scale where both scale lines form a line (in this example 7). |