Researches in colour vision and the trichromatic theory / by Sir William de W. Abney.
- William de Wiveleslie Abney
- Date:
- 1913
Licence: Public Domain Mark
Credit: Researches in colour vision and the trichromatic theory / by Sir William de W. Abney. Source: Wellcome Collection.
69/452 page 49
![lated, and the spectrum will then be “ scaled,” and the colours passing through the slit for any scale number will be known. The following is a table of wave¬ lengths for the different Fraunhofer lines and for the lithium lines :—■ Fraunhofer and Bright Lines. Colour in Bright Spectrum. A Wave- Length. Seale Number adopted in the book. i A . . . Dark red 7594 B . . . 6867 6L3 Li . . . Red 6705 59-8 C . . . Scarlet 6562 58 1 Na . D . . . Orange } Yellow j 5892 50-6 E . . . Green 5269 39'8 LM f . 5183 37-7 F . . . Blue-green 4861 30-05 Li . . . Blue 4603 22-8 G . Violet 4307 11-2 li . . . Dark Violet 3968 5-5 The visible spectrum is divided by these lines fairly equally along its total length. The difference in these scale numbers by no means corresponds with the difference in wave-length. If it be required to know the wave-length of any scale number, it can be ascertained with great accuracy by calculation. The squares of the reciprocals of wave-length (i) will lie very closely in a straight line if the scale numbers are used as abscissse. [it is useful to have a chart made on a large scale and to read off the wave-lengths from the curve.] The Production of Images in Monochromatic Light. The colour patch apparatus has a further use,1 which arises from the fact that on the screen we have a patch 1 See Paper No. 18. D](https://iiif.wellcomecollection.org/image/b31350574_0069.jp2/full/800%2C/0/default.jpg)
