Paper, 'On the colours of sky light, sun light, cloud light, and candle light' by William de Wiveleslie Abney

Description

Abney writes: 'The author has made several comparisons of the above lights throughout the different parts of their spectra, and has been able to verify their correctness by means of templates rotating in the spectrum of electric light, as described in Part II, “Colour Photometry,” ‘Phil. Trans.,’ 1889. It seemed, however, that it would be useful if the colours of these lights could be expressed in single wave-lengths, together with the amount of added standard white light, the latter being expressed in terms of the luminosity of the dominant colour, in accordance with the method brought before the Royal Society in ‘Proc. Roy. Soc.,’ 1891. When measuring light from the sky, a beam from the zenith or other desired part was reflected through a blackened tube into a darkened room in which the colour patch apparatus (“Colour Photometry,” Abney and Festing, 1886) was placed, and the image of the end of the tube was focussed on to the front surface of a cube, the front surface of which was coated with zinc white, its background being black velvet.'

Annotations in pencil and ink.

Subject: Optics

Received 9 May 1893. Read 1 June 1893.

A version of this paper was published in volume 54 of the Proceedings of the Royal Society as 'On the colours of sky light, sun light, cloud light, and candle light'.

Reference number

PP/22/1

Earliest possible date

1893

Physical description

Ink and graphite pencil on paper

Page extent

6 pages

Format

Manuscript