This is a framed pen and ink drawing entitled 'A machine for shewing the Motions of the Earth and Phases of the Moon' by the instrument-maker, author and lecturer James Ferguson (1710-1776). A date appears under the title on the left hand side which appears to read June 8 1746. The drawing shows the terrestrial sphere and the geared mechanism of the instrument, a tellurium, and there is a lengthy text giving a key to the diagram down the right hand side.

Ferguson was known as a maker of globes (including GLB0057), orreries and astronomical clocks and for using his instruments to illustrate his popular lectures on astronomy and mechanics. He was born in Scotland and, after beginning his career as a miniature portraitist, he followed his scientific interests to London in 1743. He was made a Fellow of the Royal Society in 1763. PAJ4016 is a mezzotint of Ferguson published in the year of his death.