Watt's end measuring machine

James Watt's end measuring instrument with micrometer screw,1776; probably the first screw micrometer made.

This instrument is intended to measure items very accurately by placing them between the two anvils and then advancing one using a fine micrometer screw until both are in contact with the object, the distance between them being precisely recorded on the two dials. The micrometer became an essential tool for precision enginering work. However, there are doubts as to whether this instrument was in fact made by James Watt. There is a distinct possibility that it was manufactured not c.1776 but rather closer to 1876, when it was placed in that year's Special Loan Exhibition of scientific instruments, which took place in South Kensington.