Journal of electricity, power, and gas . , on an unclouded day, daylight is almostentirely sunlight, and at this time an unobstructed sur-face receives directly from the sun, eighty-five per centof its incident light, and but fifteen per cent from thesky dome. On such occasions, the intensity is fromeight thousand to nine thousand times greater thanthe eye needs to read ordinary print, and to use the eyes to any extent under this light is inadvisable, espe-cially for close work. Too strong a glare does not increase lightingeffectiveness, but lessens it if too great, for objectscannot then be s
Journal of electricity, power, and gas . , on an unclouded day, daylight is almostentirely sunlight, and at this time an unobstructed sur-face receives directly from the sun, eighty-five per centof its incident light, and but fifteen per cent from thesky dome. On such occasions, the intensity is fromeight thousand to nine thousand times greater thanthe eye needs to read ordinary print, and to use the eyes to any extent under this light is inadvisable, espe-cially for close work. Too strong a glare does not increase lightingeffectiveness, but lessens it if too great, for objectscannot then be seen plainly. There is a certain in-tensity beyond which light not only ceases to be realillumination, but in which it defeats its own purpose byunduly fatiguing the eye. The best lighting is thatwhich produces the utmost clearness without strainingthe sight, which enables that to be most easily seenfor which the system has been planned. A very large proportion of the tired feeling sopronounced in city life, and which differs widely from. Bank Lighting- Installation of the New Indirect System. 374 JOURNAL OF ELECTRICITY, POWER AND GAS [Vol. XXXII—No. 18 the weariness resulting from a day in the country, isdue to eye-strain. It is a great mistake to suppose thatthe steady use of the eyes under proper lighting isharmful. Artificial light requires a much more careful usethan sunlight, the latter having been filtered throughmany miles of air before finding its way to the earthssurface. In this filtering process many of the moreharmful rays of light areremoved. The extreme rayswhich lie at either end of the spectrum—the rays out-side the red of the rainbow and the rays beyond the ir% 1 r ps g§S0Sz 1 An Architects Design to Conform to Decorations. blue (known as the infra-red and the ultra-violet)—are very injurious and it is these which hurt our eyesin some systems of artificial lighting. The problem is, how best to apply the essentialnatural characteristics and requirements t
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