. Light distribution and tests of new types of incandescent lamps. t the impressed pres-sure was kept at 110 volts and comparisons made with the stand-ard used in the preliminary. (1) Horizontal Distribution:- Tn order to obtain the horizontal distribution the lampwas placed in an upright position; , so that the tip pointeddirectly upwards. With the lamp in this position, readings ofthe candle power were taken from 0 to 360* azimuth at increments of (2) Vertical Distribution:- In finding the distribution in a vertical plane thelaap was first placed in the position used in finding the hori-
. Light distribution and tests of new types of incandescent lamps. t the impressed pres-sure was kept at 110 volts and comparisons made with the stand-ard used in the preliminary. (1) Horizontal Distribution:- Tn order to obtain the horizontal distribution the lampwas placed in an upright position; , so that the tip pointeddirectly upwards. With the lamp in this position, readings ofthe candle power were taken from 0 to 360* azimuth at increments of (2) Vertical Distribution:- In finding the distribution in a vertical plane thelaap was first placed in the position used in finding the hori-zontal distribution and readings of the candle power taken for0, 30, 60*, 90*, 120*, 150* azimuth. The lamp was then rota-ted through 15* in a vertical plane and readings again taken for0*, 30*, 60*, 90*, 120*, 150* azimuth. This was repeated through-out 360*in the vertical plane at increments of 15*. (c) Spherical Reduction Factor and Mean Spherical Candle Power:-Prom the vertical distrioution the spherical reductionfactor was obtained by the following method:-. The Curve AGEBA. in the figure above represents the ver-j| tical distrioution for a certain degree azimuth. Prom the points^ where the prolongation of the radii AE, AP, etc., meet the cir-I cumference, horizontal lines were drawn, and on these from thepoint where they cut the perpendicular, ab, radii vectors, givingthe relative intensities, were measured off; , AE = AE, J pP, etc. In this manner the Figure AEfPB was found. The ratio ofthe Figure AEFBto ADCB gives the spherical reduction factor. Thismultiplied by the mean horizontal candle power gives the mean sphe-tical intensity. In order to obtain a fair value, the average ofthe spherical reduction factor of both sides of the vertical dis-tribution curves for the different degrees of azimuth were found. Proof that the ratio of AEPEto a!dcb is the spherical reductionfact or. The length gm on AB corresponding to the inclinations•e and e + de is equal to cose
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