Related Object Info
spare secondary mirror for Gregorian telescope
This spare secondary mirror is concave and made of speculum metal. It is attached to a brass disk on a stalk that is set at right angles to a base, which is designed to slide in a track inside the telescope tube. There is an upright pin at the end of the slider. Exposed surfaces are painted black, except, of course, the front surface of the mirror.
The tin box has a pressure-fitting lid. The lid has a diagonal-cross ornamentation. The exterior is corroded; the interior is shiny. There are two brass tracks inside the box to secure the spare mirror in place.
This is a spare secondary mirror for the James Short Gregorian reflector of two-foot focal length (0002).