Accession No
2827
Brief Description
direct-vision spectroscope, by J. G. Hofmann, French, 1875 (c)
Origin
France; Paris; 3 Rue de Buci
Maker
Hofmann, J. G.
Class
optical
Earliest Date
1875
Latest Date
1875
Inscription Date
Material
metal (brass, steel); fishskin
Dimensions
box length 320mm; breadth 51mm; height 40mm
Special Collection
Provenance
Purchased from Christie’s, South Kensington, London, England; lot 228, 29/04/1982.
Inscription
‘I.G. Hofmann [Gothic script]
Rue de Buci, 3, Paris.’
Description Notes
Direct vision spectroscope, brass, part-covered with fish-skin. Slit with steel jaws, width adjustable by knurled brass screw. Push-focus eyepiece. Fitted box.
References
Events
Description
In 1814, Joseph von Fraunhofer noticed that the sun’s spectrum, when dispersed by a glass prism, is crossed by hundreds of fine dark lines. These lines could be used to determine the chemical composition of the sun, stars, and many other substances by spectral analysis. The first photograph of the spectrum of a star (Vega) was made by Henry Draper using a spectroscope in 1872.
There are various different forms of spectroscope, but all use a slit and collimator to make a parallel beam of light, a prism for dispersing different wavelengths, and a telescope to observe the dispersed spectrum.
Direct vision spectroscopes consist of a series of prisms of different refractive indices arranged to produce dispersion of light without deviation. This one is unusual in being bound with fish-skin, a decoration more commonly seen on telescopes.
18/10/2002
Created by: Saffron Clackson on 18/10/2002
FM:44807
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