The Art of Illumination

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McGraw, 1902 - Electric lighting - 345 pages
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Page 166 - A considerable amount of light is absorbed by the material used for the construction of shades. Table 10 shows the approximate amount absorbed by some materials. Of the great number of styles of shades and reflectors in use, only a few of the more important will be considered here. TABLE 10. Per Cent Clear glass 10 Alabaster glass 15 Opaline glass 20-40 Ground glass 25-30 Opal glass 25-60 Milky glass 30-60 Ground glass 24.4 Prismatic glass 20.7 Opal glass 32.2 Opaline glass 23.0 Fig. 47. One of the...
Page 269 - Contracts for arc lighting should never be drawn on the basis of a nominal candle-power. They should clearly specify the kind of arc to be installed, the amount of energy to be taken in each arc, and the kind of shades to be used. The nature of the fixtures should be specifically designated, whether pole tops, brackets, mast arms, or cross suspensions.
Page 36 - ... is best to consider the purpose for which the room is to be used, and match the colors under the same light conditions that will prevail in the finished room. Deep, full colors are less affected by the shadings in artificial illuminants than lighter tones of the same color. ILLUMINANT. COLOR. Sun (high in sky) White. Sun (near horizon) Orange red. Sky light Bluish white. Electric arc (short) White. Electric arc (long) Bluish white to violet. Nernst lamp White. Incandescent (normal) Yellow-white....
Page 269 - ... kind of arc to be installed, the amount of energy to be taken in each arc, and the kind of shades to be used. The nature of the fixtures should be specifically designated, whether pole tops, brackets, mast arms, or cross suspensions. These and the location of the lamps should be designated by some one familiar with practical street lighting, following the general line of the data which have here been given. The hours of lighting should be distinctly stated, with rebates for failure to provide...
Page 52 - Yellow painted wall 40 Light pink paper 36 Yellow cardboard 30 Light blue cardboard 25 Brown cardboard 20 Plain deal (dirty) 20 Yellow painted wall (dirty) 20 Emerald green paper 18 Dark brown paper 13 Vermilion paper 12 Blue-green paper 12 Cobalt blue paper 12 Black paper 05 Deep chocolate...
Page 62 - This was a spermaceti (whale oil) candle weighing one-sixth of a pound, and burning at the rate of 120 grains per hour.
Page 6 - If the intensity (candle power) of the light from an electric lamp is 4 at a distance of 150 yd., what is its intensity at a distance of 25 yd. ? 2. According to the first sentence of Exercise 1, how much farther from an electric light must a surface be moved to receive only...
Page 167 - Smith. The experiments covered more than twenty varieties of shades and reflectors, and both the absorption and their distribution of light were investigated. One group of results obtained from 6-inch spherical globes, intended to diffuse the light somewhat without changing its distribution, was as follows, giving figures comparable with those just quoted: Per cent. Ground glass 24,4 Prismatic glass 20.7 Opal glass 32.2 Opalescent glass 23.0 Arc I-amps in Foreign Cities.
Page 314 - British standard candle is denned as a spermaceti candle, seven-eighths of an inch in diameter, weighing one-sixth of a pound, and burning at the rate of 120 grains per hour. The...
Page 265 - ... little or nothing from the diffusion that is so important a factor in interior lighting; and in many instances the streets are so thickly shaded by trees that the problem of adequate lighting is very difficult and one for which local data is necessary for its solution, if it is to be done properly. The amount and distribution of streets and the needs and distribution of the population are the controlling factors in the matter and obviously these vary greatly from place to place. It is interesting...

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