Related Object Info
object glass micrometer for Cassegrain telescope
This split object glass micrometer (or heliometer) is made of brass. It is designed to fit on the end of the Cassegrain reflector by James Short (0053) and was sold together with it. There are also holes on the sleeve of the micrometer, where screws could be inserted to fix it to the telescope tube into whose end it slid. These holes match up with those on the telescope.
The longitudinal motion of the objective halves are controlled by dials and a knurled screw. Turning the screw moves (a) a pointer on a scale concentric to it; and (b) a scale in a window. Scale (a) is divided [0]-5-10-15-20 [=0], every 1 unit. Scale (b) is divided [0]-5-25 [=0], every 1 unit.
Another screw (its key missing) rotates the optical assembly around the tube axis. A scale on the circular limb is divided 90°-0°-90°, every 1°.
The original mahogany box is fitted to hold the instrument and has a sliding cover. The box lid has black stamped numerals: 9 142.