Portable reflector telescope

This is a portable Gregorian (reflector telescope).

Telescope: The barrel is made from brass. It has adjustable inclination and rotary movement (or altitude and azimuth movement). The pillar stand divides in two at the middle of the pillar. At the division point it rotates to give the azimuth movement. There is no fine adjustment mechanism. The altitude movement is adjusted by means of a brass semi-circle set into the top of the pillar. Again there is no fine adjustment. The barrel separates from the stand for storage purposes. Both the primary and secondary mirrors are specula metal. There is a rod on the side of the barrel for adjusting the collimation of the secondary mirror. The height to the top of the barrel is 495 mm and the diameter of the tube is 117 mm.

Stand: The telescope is mounted on a pillar stand with three folding claw legs.

Box and accessories: Accessories include one brass eyepiece about 100mm. long, and there is also an end cap for protecting the optics when the telescope is not in use. In addition, there are several miscellaneous pieces of equipment included in the telescope's storage box that do not appear to be original or intended for use with the telescope. When the screw-on eyepiece is attached the overall length of the telescope is 720 mm. The eyepiece cap is missing. The instrument is stored in a pine box, which is 745 mm long.

Object Details

ID: AST0946
Collection: Astronomical and navigational instruments
Type: Telescope
Display location: Not on display
Creator: Watkins & Smith
Date made: circa 1770
Credit: National Maritime Museum, Greenwich, London, Caird Collection
Measurements: Box: 745 cm;Weight: 8.45 kg
Parts: Portable reflector telescope
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