Piece of mahogany, small brass swivel handle attached

Watt, James

1 Piece of mahogany 8½” x 1½” x ⅜” small brass swivel handle attached

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.

This appears to be part of a dioptrical paradox, an optical instrument using a lens with facets ground into its surface. This is used to view an image with its component parts at a distance apart - when seen through the lens, they are brought together to create a new image. These sorts of instruments were quite popular amusements for those interested in science during the eighteenth century. Either Watt had one for himself, or he was interested in making them, in which case this item may date to Watt's early career as an instrument maker in Glasgow.


James Watt's Garret Workshop
Object Number:
brass (copper, zinc alloy) and mahogany (wood)
Major J.M. Gibson-Watt