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Optometrist's Semi-Conical Rule, by Willesden Optical Works Ltd, English, Early 20th Century

Inventory Number 15316

Acknowledgement: © History of Science Museum, University of Oxford, inv.15316

Item type
Object
Provenance
Presented by Jeri Bapasola on 8 August 2017.
Primary inscriptions
Stamped on ivorine rule "DESIGN REGISTERED BY WILLESDEN OPTICAL WORKS LTD".
Physical material
Wood
ivory
Dimensions
Height: 104mm Width: 30mm Depth: 25mm
Inventory No
15316
Accession Number
2017-8/1

Description

Wooden semi-cone for measurements in the construction of spectacles. Curved side carries a scale 5-13mm stamped "RADIUS AT CREST OF BRIDGE"; scale on flat side is 10-28 at intervals of 2 and stamped "BRIDGE BASE". Inset intothe flat face is an ivorine rule which is marked as projecting by 10mm.

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