Invented in 1876 by James Thomson, the differential analyser is a mechanical analogue computer. It solves differential equations by integration, using a wheel-and-disc to perform the calculations and displaying the answers graphically on a plotting table.
Used extensively from the 1930s, to the 1950s, it performed a large variety of difficult computing tasks. However, with the development of electronic analogue and later digital computers the differential analyser eventually became obsolete.
J B Bratt at Cambridge University built MOTAT's Differential Analyser in 1935. Constructed largely from Meccano components, it is known as the Meccano Differential Analyser No. 2, in reference to the earlier machine built by Arthur Porter from which Bratt took his inspiration.
Purchased for £100, this example came to New Zealand around 1950. It was used in the construction of the Benmore Hydro Dam and by the Department of Scientific and Industrial Research, to calculate rabbit populations. It then spent several years at Wellington Polytechnic before coming to MOTAT in the 1970s.
MOTAT's machine is a complex arrangement of cogs, string and chains, used to drive a plotter (pictured). According to an article by William Irwin, in the New Zealand Federation of Meccano Modellers Magazine, the machine qualifies as a true computer because it is programmable. Control of the calculations is achieved by altering the arrangement of cogs, wheels and gears.
Specifications
| Type | Analogue Computer | |
| Manufacturer | J B Bratt | |
| Country Manufactured | Cambridge, England | |
| Date | 1935 | |
| Materials | Metal/processed materials |
