The telescope barrel is covered in rayskin (shagreen) that has been dyed green, while the four draw tubes are made of green vellum. Black stop lines on the draw tubes indicate the optimum working length of the telescope, which is over 1000 mm. The brass fittings include a sliding eyepiece cover and screw-on objective lens cover.

This is an early example of an achromatic telescope. The achromatic lens was first developed in 1757 by the London instrument maker John Dollond (1706-61).