Accession No

3795

Brief Description

direct-vision spectroscope, by J. G. Hofmann, French, 4/4 19th Century

Origin

France; Paris

Maker

Hofmann, J. G.

Class

optical

Earliest Date

1875

Latest Date

1900

Inscription Date

Material

metal (cast iron, brass, oxidised brass, at least two white metals); glass

Dimensions

length 465mm; breadth 280mm; height 350mm

Special Collection

Provenance

Purchased from Sotheby’s, London, England, 03/10/1988.

Inscription

‘SPECTROSCOPE-HOFMANN
Construit à l’Institut d’Optique
du Dr. J.G. Hofmann, à Paris’ (main body)

Description Notes

Table-top direct vision spectroscope in brass and oxidised brass. Gold-painted cast iron tripod stand supports brass pillar on which the spectroscope is mounted in an altitude-adjustable mount. Telescope with eye-end adjusted by knurled screw; pushfit eyepiece; angle of telescope can be adjusted slightly by means of a spring and screw at the side of the main body. Collimator carries slit which can be adjusted slightly from the vertical; also a small prism which can be introduced in front of the slit to introduce light from a second, comparison, light source. A short tube mounted at right angles to the main body allows the introduction of a micrometer image onto the final image.

Condition good; complete.

References

Events

Description
Spectroscope
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.

18/10/2002
Created by: Saffron Clackson on 18/10/2002

FM:45523