[CHAPTER XV.]

Persistence of Images on the Retina—The Use of Coloured Discs p. 179

[CHAPTER XVI.]

Contrast Colours—Measurement of Contrast Colours—Fatigue of the Eye—After-Images p. 196

LIST OF ILLUSTRATIONS.

FIG.PAGE
Colour-patch apparatus[Frontispiece]
1.Spectrum of sunlight[18]
2.Carbon poles of an electric light[20]
3.Curve for converting prismatic spectrum into wave-lengths[28]
4.The thermopile[35]
5.Heating effect of different sources of radiation[38]
6.Colour-patch apparatus[42]
7.Rotating sectors[45]
8.Spectrum of Carbon Sodium and Lithium[48]
9.Interference bands[60]
10.Absorption of rays by the atmosphere[68]
11.Luminosity curve of spectrum of the positive pole of the electric light[79]
12.Rectangles of white and vermilion[82]
13.Arrangement for measuring the luminosities of pigments[83]
14.Measurement of the intensity of rays reflected from white and coloured surfaces[88]
15.Intensity of rays reflected from vermilion, emerald green, and French ultramarine[92]
16.Method of obtaining two patches of identical colour[95]
17.Absorption by red, blue, and green glasses[99]
18.Light reflected from metallic surfaces[100]
19.Intensities of vermilion, carmine, mercuric iodide, and Indian red[101]
20.Intensities of gamboge, Indian yellow, cadmium yellow, and yellow ochre[101]
21.Intensities of emerald green, chromous oxide, and terre verte[103]
22.Intensities of indigo, Antwerp blue, cobalt, and French ultramarine[104]
23.Method of obtaining a colour template[104]
24.Template of carmine[106]
25.Template of luminosity of white light[108]
26.Absorption of transmitted and reflected light by Prussian blue and carmine[107]
27.Collimator for comparing the intensity of two sources of light[109]
28.Spectrum intensities of sunlight, gaslight, and blue sky[109]
29.Comparison of sun and sky lights[111]
30.Slide with slits to be used in the spectrum[113]
31.Screen on which to match gamboge[116]
32.Diaphragm in front of prism[128]
33.Curve of sensitiveness of silver bromo-iodide[136]
34.Curves of colour sensations[139]
35.Kœnig's curves of colour sensations[151]
36.Maxwell's colour-box[152]
37.Maxwell's curves of colour sensations[154]
38.Chromatic circle[168]
39.Disc to cause alternate opening and closing of two slits[179]
40.Disc painted blue and red[181]
41.Electro-motor with discs attached[183]
42.Method of cutting disc to allow an overlap of a second disc[184]
43.Arrangement to find value of gamboge in terms of emerald green and vermilion[188]
44.Disc arranged to give approximately all the spectrum colours[192]
45.Method of showing contrast colours[196]

COLOUR MEASUREMENT

AND