280 of 520
Sorted by:
Instrument type

Geometrical Square
16th century; Italian
Brass; 220 mm in height

The open square has an inscribed quadrant and a diagonal bar incorporating a central compass ring arranged to graze the inside of the quadrant arc. A universal compass mount beneath the magnetic compass carries the instrument on a brass cylinder head now set on a wooden display stand. The pivot for an alidade is set at one corner, where the square is shaped to accommodate it. Two sides of the square have geometrical quadrant scales 0 to 60 [actually marked '90'] to 0, divided to 15, subdivided to 5, to 1 with alternate hatching, and to 1/2, numbered by 5, marked 'VMBRA VERSA' and 'VMBRA RECTA'. The inscribed quadrant has a degree scale 0 to 90, divided to 5, subdivided to 1 with alternate hatching. The compass mount is marked with 16 divisions and 32 subdivisions, the four cardinal points being marked with abbreviated names, 'SPT', 'OR', 'MI', 'OC'. Beneath a glazed cover is a magnetic needle over a blue and gold representation of the sky, sun and stars, and a target meridian line. The pivoted alidade has two sights, each being a rectangular plate with a circular hole containing an upright pierced by a pin-hole. The pinholes are aligned with the fiducial edge of the alidade. The reverse of the square has a pivoted mount for a plumb-line.

Jim Bennett

Istituto e Museo di Storia della Scienza, Firenze
Inventory no. 121

© 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:

|| Introduction || Essay || Museums || Bibliography || Conventions || Credits || Privacy || Help ||
|Catalogue entries |Handlist || Makers || Places || Articles || Glossary || Search || Home ||