Scientific Instrument Society 25th Anniversary Exhibition
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26 Ophthalmic Slide Rule
This possibly unique slide rule was devised by the noted ophthalmologist Dr. Emile Javal (1839-1907) and was used for calculating the prescribing of spectacle lenses. It was made by A. Cretes, 66 rue des Rennes, Paris, in wood, brass and glass with printed-paper scales, and instructions on the reverse.
Javal is considered the father of orthoptics and, although trained as an engineer, he later became the Director of the Ophthalmic Laboratory of the Sorbonne, Paris. He had many famous pupils, including Dr George Joseph Bull (1848-1911) who developed, in 1887, an ophthalmometer which was promoted by Javal and the construction of which was clearly based on this instrument. Also studying under him were Edmund Landholt (1846-1926) and August Schiotz (1850-1927); both went on to develop many popular ophthalmic instruments.
French, ca.1875.
Collection: Peter Delehar, London
Objects lent by Peter Delehar, London:
08. Circular Slide Rule on a Snuff Box, by Hoyau, Paris, 1816
11. Reversible Circular Slide Rule, English, c.1840
25. Slide Rules - a Selection of the Original Pocket Calculators
27. Triangular Slide Rule with Four Sliders, by Elliott, London, c. 1870
28. Oil Calculation Slide Rule Designed by Forrest M. Towl, New York, c. 1889
29. Master Rule and Gauging Slide Rule, by Dring & Fage, London, 19th Century
30. Anderson Celluloid Gridiron Slide Rule, by Casella & Co, London, c. 1903
31. Slide Rule in a Drawing Scale, by J. Casartelli, Manchester, c. 1870
32. Circular Slide Rule, by Joseph Lamb, London, c. 1827
33. Roubicek Circular Slide Rule for Surveying, by Neuhöfer & Sohn, Vienna, c. 1870
34. Annular Slide Rule, by Elliott Brothers, London, c. 1875
36. Box Sextant with Integral Slide Rule, by Troughton & Simms, London, c. 1870