Maurice Davies has not identified the source of the main diagram, which does not appear in Christoph Scheiner, Pantographice, seu ars delineandi, Rome 1631,1 the first edition of which Turner could have consulted at the British Museum (since transferred to the British Library, London), where no later editions are listed.
A mathematician and astronomer, Scheiner (1573–1650)2 devised a form of pantograph (a pivoting trellis-like framework allowing the duplication or enlargement of an image through a parallel tracing process using simple geometrical relationships); the rough, smaller diagram on the present page appears to show the instrument.
Davies 1994, pp.98, 289, 310 note 78.
See Albert Van Helden, ‘Christoph Scheiner (1573–1650)’, and Richard S. Westfall, ‘Scheiner, Christoph’, The Galileo Project, accessed 28 May 2008, respectively http://galileo
.rice and http://galileo .edu /sci /scheiner .html .rice. .edu /Catalog /NewFiles /scheiner .html