image x40_21_plate 2
Image number: RS.10046
Credit: © The Royal Society
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The Sun, observed through a prism




James Sowerby (1757-1822, British), Naturalist

Object type

Library reference





height (print): 258mm
width (print): 208mm


   > Optics


Colours produced by sunlight observed through a prism.

The author and illustrator described his projected observations: “I found it might give much satisfaction if I were to examine the light from the full sun’s rays, as an original source, in the open air. I therefore took the usual three-sided prism, and was highly gratified by observing white in the refracted reflexion of the sun, as seen in the oval form, light on the face of the prism, and the three primitive tints, a fine yellow, a rich red, and a light blue (see Tab.2 fig. 1 and 2) and I found, by turning the prism, very beautiful phenomena took place within it...At the same time as the above, may be seen refracted immediately from the sun’s most brilliant rays, upon any object within a few inches, a fine image of the prism bordered lengthwise, by the same three tints (see Tab 2 fig.3).”

Plate 2 from the monograph A new elucidation of colours, original prismatic, and material; showing their coincidence in three primitives, yellow, red and blue..., by James Sowerby (London, Richard Taylor and Co., 1809). Inscribed “Tab.2” top right and “Nov..1.1807.Publish’d by Jas. Sowerby London.”

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