Portable reflector telescope

This is a portable Gregorian (reflector) telescope. It is signed JAMES SHORT EDINBURGH 1734.3.27 referring to the date it was made.

Telescope: The barrel is made of brass and painted black. It is a Gregorian of 76.2mm (3 inch) aperture and about 457.2mm (18 inch) focal length. An Huygen's eyepiece is used. It has adjustable inclination and rotary movement (or altitude and azimuth movement). The azmiuth movement is adjusted by a handle at the base of the pillar. The altitude movement is adjusted by means of a brass semi-circle set into the top of the pillar. There is a screw-on eyepiece with its cap missing. The object end has a screw-on brass cap. Within the barrel are primary and secondary specula (mirrors). There is a screw thread for focusing which is done by moving the secondary mirror by a rod attached to the side of the barrel. The length of the telescope with the eye piece and object cap is 625 mm. The paint on the brass tube is in bad condition.

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

Object Details

ID: AST0958
Collection: Astronomical and navigational instruments
Type: Telescope
Display location: Not on display
Creator: Short, James
Date made: 1734
Credit: National Maritime Museum, Greenwich, London
Measurements: Overall: 505 mm x 460 mm x 300 mm
Parts: Portable reflector telescope