Portrait of a gentleman, half-length, in a red robe and green cap, with an Ellis aquatic microscope

The present portrait shows a naturalist or botanist with British scientist John Ellis's (1710-1776) aquatic microscope. Ellis's microscope, invented in 1752, and developed from an earlier design by John Cuff, was used to study small aquatic organisms and pond-life, the free movement of its lens making it easy to scan the subject, its large circular stage accommodating a wide spectrum of samples. The pattern was very influential in the development of many later microscopes, and was illustrated and expounded at length in 'Essays on the Microscope' by George Adams (1750-1795), instrument maker to King George III.