Ten cylinders papered with figures, a crude calculating machine

Watt, James

1 Box of 10 cylinders papered with figures, 2 papers loose, ? calculating machine

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 is a crude apparatus for aiding multiplication, comprising a set of rollers marked out in a manner similar to Napier’s Rods. A deal case, lined inside and out with paper, is fitted inside with softwood battens to form a frame within which ten softwood rollers are carried on brass spindles. One long broad face opens on brass hinges to allow the faces of the rollers to be seen, and the adjacent long narrow face opens on similar joints to give access to wing terminals on the spindles by which the rollers are rotated. Each roller was covered with paper ruled into squares, on which was laid out a multiplication table in a manner similar to that found on Napier’s Rods: multipliers and multipicands from 0 to 9 run along and around each roller, and the products are written into the corresponding squares with diagonal divisions to separate units from tens. Inside the larger hinged cover is written, in ink: “James / James …[indecipherable]”. This instrument has the appearance of having been a youthful essay. Watt's interest in mathematics went back to an early age: Richard Hills notes that his father inherited portraits of John Napier and Isaac Newton. And others told stories of Watt doing calculations in chalk on his bedroom walls because he'd left his slate in school.


James Watt's Garret Workshop
Object Number:
brass (copper, zinc alloy), paper (fibre product) and softwood
Major J.M. Gibson-Watt