Related Object Info
secondary mirrors for Gregorian telescope
A tin box with a hinged lid has a corroded exterior and shiny interior. It has two sets of copper tracks on opposite sides of the box. These are designed to hold two secondary mirrors for the four-foot Short telescope (0001a).
Each mirror is concave and made of speculum metal, which has been attached to a brass disk on a stalk that is attached to a brass base. The base has four slits and serves as a slider in the tracks. The metal fittings to be exposed in the tube are painted black, except for the mirrors' front surfaces. Three, brass, fine-adjustment screws are on the backside of each mirror for collimation.
One secondary is currently inside the tube of 0001a. The one in the box has a diameter of 2.8 cm.