Mathematical instruments, 1747.
© Science Museum / Science & Society Picture Library
Coloured frontispiece showing a number of mathematical instruments. At the top are three proportional compasses, beneath and to the right are several drawing instruments and a compass. In the middle and bottom are a plane scale, protractor & parallel ruler and two sectors. 'Made & contrivd by Tho. Heath in the Strand, London' is written above the upper sector. Illustration from 'A treatise of such mathematical instruments, as are usually put into a portable case' by John Robertson (1712-1776), published in London 1747.