An early, large and elegant brass spherometer by Lecomte in Paris, circa 1840

An early, large and elegant brass spherometer by Lecomte in Paris, circa 1840

350 euros

Circa

1840s'

Country of manufacture

France

Categories: Physics & Chemistry, Scales Weights & Measures

Description

A very elegant French brass spherometer signed on the circular disk “Lecomte à Paris”. The instrument can be dated from circa 1840s’. Lecomte was a maker of physical and measuring instruments.

The present example of spherometer is a large example (around 20 cm height and 19 cm between each leg) but with a very elegant shape because of its curved long curved legs.

 

Rare early example.

 

“Spherometers are used to measure the radius of curvature of the surface of a lens. If the radii of both surfaces of the lens and the index of refraction of the glass are known, the focal length can be found using the Lens-Maker’s Equation.

   When the three outer legs are placed on a flat surface and the central leg screwed down to touch the surface, the zero reading is obtained. The vertical scale reads in millimeters, and the scale around the edge of the circular disk may be divided into as many as 1000 graduations. The design dates from 1810 and is due to Nicolas Fortin and made for him by the French optician Robert-Aglaé Cauchoix.”

For some late examples see the link here :

http://physics.kenyon.edu/EarlyApparatus/Optics/Spherometer/Spherometer.html

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FR Le Zograscope

Established by Alexandre Piffault in 2014 and based in Paris at 5 rue de Condé, 75006, very close to Odéon, Le Zograscope specializes in antique and rare books in Science, Medicine and Technology, and rare antique instruments in the same fields. We have especially a strong interest in early and continental microscopy, early and special mathematical/drawing instruments, medical and surgical instrument, and rare technology.

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