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acuity altering amounts appear applied artificial blue blue-green brightness CHAPTER color colored light combination compared considerable considered contrast curve daylight depends desired direct disk dyes effect energy equal experiments fact field filters flicker given glass grating gray green illuminant illustrated importance indicated influence instance intensity interest latter less lines manner means measurements mercury method mixing mixture monochromatic object observers obtained ordinary owing painting photometer photometry pigments placed plate position possible practically preference present principle prism produced purple radiation range rays readily reflected relation relative represent respectively rotating satisfactory saturation screen seen sensation Showing shown in Fig simple slit solution spectral character spectrum sunlight surface Table theory tint tion transmission transmitted tungsten lamp usually values various varying viewed violet visible vision visual wave-length waves white light yellow
Page 285 - Its soul is the spirit of light — of sunlight, of moonlight, of starlight — which plays ceaselessly across the face of the landscape, veiling it at night in mystery and shadow, painting it at dawn with the colors of the pearl-shell, and bathing it at mid-day in a luminous glory.
Page 143 - If any part of the retina is excited by intermittent light, recurring periodically and regularly in the same way, and if the periods are sufficiently short, a continuous impression will result, which is the same as that which would result if the total amount of light received during each period were uniformly distributed throughout the whole period.
Page 189 - In the impulse itself we have the physiological basis of the sensation of light, and in the quality of the impulse the physiological basis of the sensation of colour. The impulse being conveyed along the optic nerve to the brain...
Page 77 - I'll be hanged if I can describe this red — it's not Turkish and it's not Roman and it's not Indian, but it seems to partake of the two last and yet it can't be either of them because it ought to be able to go with vermilion. Ah, what a tangled web we weave — anyway, with what brains you have left choose me and send me some — many — patterns of this exact shade.
Page 188 - ... and a photograph is formed. The decomposition of the visual purple by light chemically stimulates the ends of the cones, and a visual impulse is set up which is conveyed through the optic nerve fibres to the brain. I have examined the retinas of several monkeys after they had been kept in a dark room, and found that the visual purple was to be seen in the yellow spot, but situated between, and not in, the cones.
Page 77 - Perhaps in the same way it might amuse you to send us any pattern of wall paper that might strike you as cheap, pretty and suitable for a room in a hot and extremely bright climate. It should be borne in mind that our climate can be extremely dark too. Our sitting-room is to be in varnished wood.
Page 77 - ... wall paper that might strike you as cheap, pretty and suitable for a room in a hot and extremely bright climate. It should be borne in mind that our climate can be extremely dark too. Our sitting room is to be in varnished wood. The room I have particularly in mind is a sort of bed and sitting room, pretty large, lit on three sides, and the colour in favour of its proprietor at present is a topazy yellow. But then with what colour to relieve it? For a little work-room of my own at the back I...
Page 189 - that the quality of the impulse is perceived by a special perceptive center in the brain within the power of perceiving differences possessed by that center or portion of that center. According to this view the rods are not concerned with transmitting visual impulses, but only with the visual purple and its diffusion.
Page 77 - Our sitting-room is to be in varnished wood. The room I have particularly in mind is a sort of bed and sitting room, pretty large, lit on three sides, and the colour in favour of its proprietor at present is a topazy yellow. But then with what colour to relieve it? For a little work-room of my own at the back I should rather like to see some patterns of unglossy — well, I'll be hanged if I can describe this red. It's not Turkish, and it's not Roman, and it's not Indian; but it seems to partake...
Page 137 - Le Courrier du Livre reported the legibility of various combinations for reading at a considerable distance, the most legible print being black on a yellow background. The order of merit was found to be as follows: 1. Black on yellow 8. White on red 2. Green on white 9. White on green 3. Red on white 10. White on black 4. Blue on white n. Red on yellow 5. White on blue 12. Green on red 6. Black on white 13. Red on green 7. Yellow on black " It is noteworthy that in this list the customary black-onwhite...