Signed by James Kynvyn
Dated 1595; London
Brass; 660 mm in length
The two arms of the folding rule are connected by a flat, 3-leaf hinge, incorporating a slot for a now missing clamping mechanism. The hinge has a semicircular degree scale on both faces 0 to 180, divided to 10, subdivided to 5 and to 1, numbered by 10. Each arm has a linear scale on the recto side 0 to 770, divided to 20, subdivided to 10, to 2, to 1 and to 1/2, numbered by 10. Signed on this side: 'Iacobus ? Kynuyn ? fecit ? 1595 London'.
The reverse has a line on each arm with 2 sector scales whose positions are marked by dots. One pair run outward 20 to 2 by 1, non-linear increasing; the second set of dots are on the same lines and are circled to distinguish them, running outward 20 to 3 by 1, non-linear increasing. Where a dot serves both scales (6 / 19, and 2 / 6) it is marked by a circle with points, like a star.
Two subsidiary arms are stowed in the inner edges of the principal arms. They can be folded out and fixed together to form a geometrical quadrant, with an inner scale of degrees 0 to 90, divided to 5, subdivided to 1, numbered by 5, and an outer geometrical quadrant scale 0 to 300 to 0, divided to 5, subdivided to 1, numbered by 5, as well as a shadow-square scale 0 to 12 to 0, divided to 1, numbered by 1. These scales are repeated on the other side of the subsidiary arms.
Istituto e Museo di Storia della Scienza, Firenze
Inventory no. 2516
© Istituto e Museo di Storia della Scienza, Firenze. All rights reserved. Information and images provided here may not be reproduced in any form or by any means without the prior written permission of the museum.
Basic URL: http://www.mhs.ox.ac.uk/epact/catalogue.php?ENumber=69822