Menu
478 of 520
Previousnext
FirstLast
Sorted by:
Instrument type
Maker
Place
Date
Overview
Details
 Catalogue


Surveying Instrument
Unsigned
16th century; Italian
Brass; 180 mm in radius

A plate comprising the eighth of a circular disc has an alidade pivoted at its apex and a fixed sight on each straight edge. The limb has an inner degree scale 0 to 40, divided to 5, subdivided to 1, numbered by 5, and on the outer side of the scale a diagonal scale with lines running in alternate directions, divided to 20 minutes by concentric arcs and to 4 minutes by dots. The plate has a right-angled isosceles triangle with its hypotenuse on one edge of the octant, and the two smaller sides with scales 0 to 100, divided by 5, subdivided to 1 with dots, numbered by 5. From the 5 divisions parallel lines are drawn across the triangle in a sinecal arrangement, and the dotted subdivision is continued on these parallels. The alidade has slit and pinhole sights and a small handle, and a scale 0 to 140 with the same unit as the scales on the triangle, divided to 5, numbered by 5.

The reverse of the octant plate has a cylindrical bar fitting into a sleeve mount in which it rotates and can be clamped by a screw. The sleeve is set on a compass mount above a cylinder, thus forming a universal mount.

Jim Bennett

Istituto e Museo di Storia della Scienza, Firenze
Inventory no. 20

© 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=52492

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