Author describes, at first, the brief sketches of the method of color analyais, laying stress upon the spectrophotometry, monochromatic analysis and trichromatlc analysis. He then states his experiment on the trichromatic analysis of various electric incandescent lamps, the sun and blue sky, colnparing his results with those of another authors. Finally he checked his results by the use of transmission curves of the color filters used and the luminosity curve of these illuminants.

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We have limitted the extent of the glare sensation which is whitten in this paper, by classifying it into four kinds physically thus explaining each of them by the theory of Dr. Ettle (English) special explanation on the automobile head-light and street lighting is made though these are a part of above four.
At the end, we have described the eliminating methods of glare for a natural and artificial light sources, considering the harmful influence of it for our bodies.

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The blackening of the ordinary lamp occurs due to following causes: -
(1) Disintegration of the filament due to chemical action between incandescent filament and residual gases which adhere to the surface of the glass or are occluded in the filament.
(2) Disintegration of the filament due to electrical action of residual gases.
(3) Disintegration of the filament due to thermal evaporation of the filament.
It is well known fact that of residual gases, water vapour is the only onewhich causes the blackening of the bulb due to first reason. We can easily. and perfectly eliminate this by heating the bulb at high temperature during exhaust, and by using P₂ 0₆ which is formed by the red phosphorus in the lamp.
The presence of the residual gases even without water vapour causes the Edison effect and a rapid blackening of the bulb due to second reason but these gases, except argon, disappear electrically or chemically by the incandescent filament, and amount of argon in ordinary lamp after exhaust is too small to measure, therefore blackening due to second cause is not large amount. These are prevented by placing the conductors near the filament, and appling the electric field between them.
The conclusion to be drawn from above mentioned facts is that blackening of the bulb of ordinary well made lamps is not caused by residual gases. Main cause of the blackening in well made lamps is the evaporation of the filament. And this evaporation is reduced by filling the inert gas in the bulb. For this purpose we must investigate loss due to convection and coma current through the inner gases as a function of the pressure of the gases in the bulb and then we must determine the b, st pressure.

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