AO Additive Effective Power Phoroptor
 Catalogue Number: 3776 AO Additive Effective Power Phoroptor Category: Equipment Sub-Category: Refractor Phoropter Phorometer Corporation: American Optical Co Year Of Publication/Manufacture: c1934 Time Period: 1900 to 1939 Place Of Publication/Manufacture: USA Publisher/Manufacturer: American Optical Co Description Of Item: Black enamelled instrument (phoropter or refractor head) with fitting to mount on an arm of an instrument stand. Each side has inbuilt options of pinhole, plus and minus 0.12DS, red filter, prisms of 6 PD vertically, 10 PD BI, 15 PD BO and an occluder. Each side also has externally mounted clear Maddox rods and variable (Risley) prisms. Plaque on front reads 'AO ADDITIVE EFFECTIVE POWER PHOROPTER/ MADE IN U.S.A./UNDER ONE OR MORE OF U.S. PATENTS Nos 1,409,680/ 1,423,091/ 1,455,457/ 1,483,786/ 1,611,167/ 1,794,571/ 1,887,049/ AMERICAN OPTICAL COMPANY/ U.S.A.' Also black cotton storage bag. Size: 260mm W x 270 mm H x 70 mm D. Historical Significance: The last of the listed US patent numbers, 1,887,049 , was granted on November 8 1932. How Acquired: Donated by William Law Optometrist Date Acquired: October 2019 Condition: Very good Location: Archive room. West wall. Unit 1 Drawer 4 |