Light, photometry and illumination : a thoroughly revedof ''Electrical illuminating engineering'' . ° \\/ /N>7^-^â ^^--\-^^y\ /\ / s SOO^^^^r-^^ ^1 ^P :/-J \y /30°^~~--^ Xi;;;;;^ 400_____-ââY^ /l5» 0° 15\ ^^ 30\ Fig. 158.âCharacteristic curves Mazda 100, 150, and 250-watt, 100-125-volt, bowl-frosted lamps with intensive reflectors. be placed at a greater height than h without impairing the uni-formity of the illumination. It is obvious from the shapes ofthese polar curves that the extensive type of distribution wouldbe used in rooms having low ceilings or low fixtures or where itis desir
Light, photometry and illumination : a thoroughly revedof ''Electrical illuminating engineering'' . ° \\/ /N>7^-^â ^^--\-^^y\ /\ / s SOO^^^^r-^^ ^1 ^P :/-J \y /30°^~~--^ Xi;;;;;^ 400_____-ââY^ /l5» 0° 15\ ^^ 30\ Fig. 158.âCharacteristic curves Mazda 100, 150, and 250-watt, 100-125-volt, bowl-frosted lamps with intensive reflectors. be placed at a greater height than h without impairing the uni-formity of the illumination. It is obvious from the shapes ofthese polar curves that the extensive type of distribution wouldbe used in rooms having low ceilings or low fixtures or where itis desirable to light a large area. The intensive distribution isused for medium and average conditions where more than onelamp or outlet are required. The focusing distribution is usedwhere the lamps are placed comparatively high above thereference plane. PRINCIPLES OF INTERIOR ILLUMINATION 265 In Fig. IGO are shown the illumination curves for one and fortwo 250-\vatt tungsten lamps equipped with extensive, intensiveand focusing types of reflectors. The details are given in thefollowing table:. Fig. 159.âCharacteristic curves Mazda 100, 150, 250-watt, 100-125-volt, bowl-frosted lam^js with focusing reflectors. Table 41Relative Location of Lamps with Different Types of Reflectors. Curve Reflector Height above reference plane (feet) Distance between lamps (feet) DistanceHeight Number oflamps Di Distributive Intensive 9912121515 1 D2 Ii 18 2 21 I2 15 2 Fi 1 F2 12 2 266 LIGHT, PHOTOMETRY AND ILLUMINATION The relative distributions of illumination from a lamp equippedwith these three types of reflectors when placed at the same heightsare shown in Fig. 107, and from two lamps equipped in the sameway are shown in Fig. 108, the location of the lamps being thesame in each three cases. The False Ceiling.âAnother class of direct lighting consists inplacing the lamps above false ceilings of milk or opal glass,the object being to secure a well-diffused ill
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectlight, bookyear1912
