Protractor for marking up ophthalmic lenses

Catalogue Number: 2219
Protractor for marking up ophthalmic lenses
Category: Equipment
Sub-Category: Dispensing tool
Corporation: Cahn-Standard Optical
Year Of Publication/Manufacture: c 1910
Time Period: 1900 to 1939
Place Of Publication/Manufacture: Los Angeles, USA
Publisher/Manufacturer: Cahn-Standard Optical Co
Description Of Item: Protractor for marking up ophthalmic lenses prior to cutting and shaping the lenses and fitting them in a spectacle frame, metal with folded sides so the protractor sits on an incline with two slots for measuring lens thickness, yellow enamel with a 360 degree protractor, several other special purpose scales and four aide de memoir data lists. Back fold bears the words 'CAHN'S PROTRACTOR / CAHN-STANDARD OPTICAL CO / LOS ANGELES'. Decorative design on the two folded down sides.
Historical Significance: This a dispensing aid commonly used in the 20th C to mark lenses so they are correctly centred and oriented when fitted to a spectacle frame after the lenses have been cut to shape and edged, The Cahn-Standard Optical Company is listed in the Los Angeles City Directory for 1908 and is identified in a photograph taken about 1910 as a tenant in the Guarantee Building in downtown Los Angeles.
How Acquired: Donated by Bruce Dudon, Spectacle maker, Woodend
Date Acquired: April 2013
Condition: Fair. Enamel damaged in places, some rust
Location: Archive office. East wall shelves unit 3. Drawer 9

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