Whitworth's workshop length measuring machine for measuring to an accuracy of 1/40,000 inch.

Whitworth’s 'Millionth Measuring Machine’ was unsuitable for ordinary workshop use and instead this model was used, which could measure accurately up to 1/40,000 inch. It is a good example of the importance Whitworth placed on accuracy in the workshop and the 'end measurement’ technique, essentially measuring by touch rather than by sight as was the old technique of measuring with calipers and a rule.