Nineteen assemblies comprising the jointed arms for the peep-sight of the Perspective Instrument

19 assemblies comprising the jointed arms for the peep-sight of the Perspective Instrument. The arm to be fixed to the case is a straight bar of mahogany, of rectangular cross-section, with the ends guarded with brass like those of a wooden rule, each drilled with a hole. The other piece. also of mahogany, is lighter and of a tee section. The two are jointed by a brass elbow-fitting. The free end of the lighter bar is fitted with a brass guard that also forms a socket for the sight vane, a leaf-shaped piece of brass with a pin to fir the socket. Each has two peep holes, of different sizes, and a small piece swinging on a rivet to cover whichever hole is not in use. One assembly lacks the sight vane [but there is one in the tall cabinet!].

This item is part of the contents of the workshop that Scottish engineer James Watt developed at his home, Heathfield, at Handsworth, Birmingham, from c.1795 through to his death in 1819. Although Watt is best known for his work on the steam engine, his workshop contains a wide variety of objects from many different projects, from chemistry to sculpture-copying.

The description of the item was written by Edward Collins, the land agent responsible for Heathfield when the workshop was given to the Science Museum in 1924. Collins could not always identify what he was looking at, but always described what he saw clearly. This has allowed his descriptions to form the basis of subsequent research.

One of his Watt’s first successful innovations was an ingenious drawing tool, to help an artist to accurately capture the perspective of a scene. The instrument came in several sizes, and he used one himself for drawing and mapping. Their manufacture involved a team of Watt’s workmen each producing different parts, which is revealed by careful study of the fragments of the apparatus in the workshop. It was an effective instrument, which was soon copied by George Adams, one of the foremost London instrument-makers.