Accession No

2120

Brief Description

prism

Origin

Maker

Class

optical

Earliest Date

Latest Date

Inscription Date

Material

glass; metal (brass)

Dimensions

length 185mm; breadth 135mm; height 100mm

Special Collection

Provenance

Transferred from Institute of Astronomy, University of Cambridge, Cambridge, England, 10/1975. Transferred from Solar Physics Observatory, South Kensington to Institute of Astronomy, Cambridge, unknown date.

Inscription

‘AST.LAB. 55’ [crossed out]
‘S.P.O. 6’

Description Notes

Large brass-cased 90˚ glass prism. Case of brass plates held together by screws. Oxidised interior. 2 plates of right angle have circular apertures. End plates tapped for mounting. Back plate has crown surmounting crest of initials.

Condition

References

Events

Description
Prism
A prism consists of a translucent piece of glass or crystal, usually triangular in cross section, which is used to separate light into a spectrum of its separate colours.

The instrument works because different wavelengths of light are refracted (bent) by different amounts as they enter and leave the prism; the shorter wavelengths (towards the blue end of the spectrum) are refracted by the greatest amount, and the longer wavelengths (towards the red end) are refracted the least. This spreads out normal white light, which is a mixture of all the different colours, into its constituent parts and produces the rainbow effect of a spectrum.

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

FM:43406