Light and lighting . reference circles described around the lamppomts as centres in Fig. 1 show the zonestaken, tin- corresponding angles of eleva-tion being marked on tin- polar diagram(Fig. 2). There 1- some approximationnecessary in dealing with tin results are : Flux in lumens from VI. 584 I 2336. Flux in lumens from Lamp- II. ami 691 • 2 i Total flux mi reference plane 3718. THE ILLUMINATING ENGINEER (april) 193 Table of Results. Fig. 1. Lamp. 27a. 30a. 33a. 36a. 39a. 42a. 45a. 48a. 57a. 54a. I. 0-168 0113 0-0714 0-0511 0-028
Light and lighting . reference circles described around the lamppomts as centres in Fig. 1 show the zonestaken, tin- corresponding angles of eleva-tion being marked on tin- polar diagram(Fig. 2). There 1- some approximationnecessary in dealing with tin results are : Flux in lumens from VI. 584 I 2336. Flux in lumens from Lamp- II. ami 691 • 2 i Total flux mi reference plane 3718. THE ILLUMINATING ENGINEER (april) 193 Table of Results. Fig. 1. Lamp. 27a. 30a. 33a. 36a. 39a. 42a. 45a. 48a. 57a. 54a. I. 0-168 0113 0-0714 0-0511 0-0287 0-0198 0-1441 00107 00079 00045 IT. 0-930 0-857 0-732 0-561 0-390 0-229 0-168 01135 00742 0-049S III. 017 0-253 0-390 0-55 0-71 0-856 0-925 0-856 0-710 0-550 IV. 0-168 0-109 0-0709 0-048 0-0287 00201 00142 0-00985 0-00676 000507 V. 0-925 0-880 0-740 0-560 0-390 0-246 0-168 0112 0082 0049 VI. 0-168 0-259 0-389 0-55 0-726 0-88 0-925 0-88 0-726 0-55 Totals 2-529 2-471 2-393 2-320 2-273 2-251 2-314 1-982 1-607 1-209. FEET FROM CENTRE OF FiaS ILLUMINATION ON LINE aL OBSERVED — FULL LINECALCULATE D-POrTED LINE i\ % ?—.^ ^ ^ \ >». a >* a S ? 0 FEET FROM CENTRE OF ROOM FIG4 ILLUMINATION ON LINE d FIG I OBSERVED—FULL LINECALCULATED — DOTTED LINE 194 THE ILLUMINATING ENGINEER (april) The floor area is 1940 Bq. ft., hence themean horizontal illumination in foot-candlet 3718L940 = 1-91 a figure in close agreement with thatobtained by the first method, the exactvalue of which was 1-97 mean hemispherical candle-power is partly reflected and partly absorbed bythe walls. Tin- observed increase overthe direct flux is the difference, 4850—3760 1090 lumens Neglecting light reflected from the wallson to the roof, the coefficient of reflection of tin- walls is. 10901760 = 62% l» >-;- _—_—, — —J 0 ~~ ?*• peer FRon centre or room- FIQ S ILLUMINATION On LINE g Fid I OBSERVED —CALCULATSD - FULL LINEDOTTED litE I in. hence the total fl
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