Eden's Screw diameter measuring machine; floating head type, 2" capacity with a pair of 14 t.p.i. needles.

This machine was made by Taylor, Taylor and Hobson Ltd. to a design produced by Mr. E. M. Eden in 1915 to allow rapid and accurate measurement of the screw gauges required during the First World War (1914-18). Two carriages running on balls in V grooves allow free axial movement for the measuring head, whilst it is always held at right angle to the work. Two wires of a size to suit the thread to be measured are suspended from the arms provided and the micrometer head is used to measure across these to determine the effective diameter.