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absorption actinic amongst angle appear artificial beam beautiful becomes blue blue-green bluish bluish-green brightness calorescence change of hue chatoyant chlorophyll chromatic circle coal-tar colour-sensations coloured light colouring matters combination complementary colours compound constituents contrast of tone copper dark decorative disc dull effect emerald green employed enamels example fibrils film fluorescence gamboge glass gold gradation greenish greenish-yellow harmonies heat-rays illuminated kind lapis-lazuli large number layer less light reflected luminosity luminous lustre medium metallic mingled mixed mixture nearly neutral element neutral grey normal obtained opaque optical orange orange-red orange-yellow painted pairs pale paper particles phosphorescence piece pigments prism produced Prussian blue pure purity purple rays refraction refrangibility retina rotating sectors sensation shades silver simultaneous contrast slit solar spectrum solution spectral substances surface theory three primaries tinctured tints tion translucent transmitted transparent turquoise ultramarine vermilion vibrations violet visible wave-length waves white light yellow yellow film
Page 55 - ... by the addition of black. Tones belonging to any of the above series are commonly spoken of as shades; but it is better to limit, the use of this term to admixtures with black. A scale is a regular series of such tones as those which have been defined above. So each hue admits of three scales : (1) The reduced scale — that is, the normal hue mixed with increasing amounts of white, thus forming tints.
Page 5 - ... bodies by the aid of the light which they reflect irregularly, or scatter ; a perfectly regular reflection gives, on the contrary, an image of the source of light, not of the object illuminated. It is only light which is regularly reflected which can be shown to obey the great law of reflection, which is this : — -The angle which an incident ray of light makes with a perpendicular to the reflecting surface, is equal to the angle which the reflected ray makes with that perpendicular ; in other...
Page 133 - CONTRAST. 1. The Harmony of Contrast of Scale is produced by the simultaneous view of two or more distant tones of the same scale. 2. The Harmony of Contrast of Tones is produced by the simultaneous view of two or more tones of different depths belonging to neighbouring or related scales. 3.
Page 55 - ... regular series of such tones as those which have been defined above. So each hue admits of three scales. 1. The reduced scale — that is, the normal hue mixed with progressive increments of white, thus forming tints. 2. The darkened scale — that is, the normal hue mixed with progressive increments of black, thus forming shades.
Page 4 - We said above that bodies differ not only in the amount but in the quality of the light which they reflect. Now one of the chief differences as to quality of light is the difference of colour. Powdered vermilion reflects...
Page 53 - Rood, for a prismatic spectrum divided into 1,000 parts between the fixed lines A and H. Rood, moreover, has named the several coloured regions, so that with these two data (of spaces and luminosities) he has been able to construct the following Table showing the Amounts of Coloured Light in 1,000 Parts of White Sunlight.
Page 97 - ... are most contrasted in tone, and the others less so in proportion to their distance from the line of contact. The experiment should now be repeated with a background of black velvet, and again with a background of gray paper lighter in tone than either of the strips.
Page 62 - Imligo-blue : a d.irk blue, with black' and green. 9. Duck-blue : blue, with a great deal of green and a little black. 10. Sky-blue : a bright, rather greenish blue. Now there is scarcely a single description amongst these hues which does not challenge criticism, even apart from the general lack of orderly sequence and of precision which they exhibit.
Page 53 - Red, 54 ; Orangered, 140 ; Orange, 80 ; Orange-yellow, 114; Yellow, 54 ; Greenish-yellow, 206; Yellowish-green, 121 ; Green and blue-green, 134; Cyan-blue, 32; Blue, 40 ; Ultramarine and blue-violet, 20 ; Violet, 5.
Page 73 - ... of three orders, what we may call red fibrils being particularly acted upon by such long light waves as those in the red, but being also stimulated in a minor degree by the shorter waves in the green, and still less by those in the blue, the green fibrils will respond most actively to green waves, and in some measure also to red and to blue waves ; while the blue fibrils will be most excited by blue waves, though not uninfluenced by green and even by red waves. It follows that when all three...