For a period during the 1960s and 1970s, every larger Colchester lathe was issued not only with a standard inspection form (shown at the bottom of the page) but a certificate showing the results of testing a turned sample on a Talyrond machine. This ingenious device (one of several types of high-precision testers made by the Taylor-Hobson Company and widely used throughout industry) was able to produce a trace that depicted, using an exaggerated scale, any deviation from true roundness to an accuracy of one-hundredth thousandth of an inch..

A Ferranti visual tester being used to check inner plates for flatness of a sample from a production batch of screwcutting gearboxes

Inspecting the roundness of a Mascot spindle with a tester that produced a vertical linear read-out.

The Rank Talyrond roundness tester in action and a sample of the read-out chart.