This is a portable Gregorian reflector telescope by Francis Watkins, an instrument maker based in Charing Cross, London, from 1746-1782. The expedition by Captain James Cook to view the 1769 transit of Venus from Tahiti included a Gregorian telescope by Watkins of 18-inch focal length among its equipment. However, this type of instrument was also sought-after by wealthy individuals with an interest in astronomy.

The telescope's barrel is made of brass and has a smaller sighting telescope on the top. There are primary and secondary specula within the tube, with the latter focused via a screw thread and rod attached to the side of the barrel. The telescope is mounted on a brass pillar and has three collapsible claw legs, and has adjustable inclination and rotary movement.