1182 
combining seven readings: the sum represents the intensity of the 
light at the middle point. 
The sums thus arrived at are then reduced to the intensities with 
which the eight colours concerned occur in the light of the sun by 
multiplying each by a special coefficient. 
The final caleulation of the resulting colour by PERNTER’s method, 
which is based on Maxwerr’s colour-equations, consists in dividing 
the intensity found for each of the eight colours over the three 
primary colours red, green and violet (.630 u, .528 u, and .475 u) 
and thenee to deduce the colour-equations which yield the final 
colours, each with the percentage of white with which it is mixed. 
S R G V 
| | 
B | 23 1.000 0.000 0.000 
C 94 0.904 0.011 | 0.085 
D 262 0.557 | 0.446 —0.003 
E 153 —0.006 0.993 | 0.013 
x 118 — 0.068 | 0.602 0.466 
F 130 —0.061 0.346 0.715 
y 152 0.020 0.007 0.973 
68 0.000 —0.059 | 1.059 
Ww | 240 | 383 | 371 
Column S gives the proportional numbers for sunlight, 2, G and 
V those for the primary colours. The bottom row gives the pro- 
portion of the primary colours in white (W). 
The following table contains the intensity as obtained for a few 
directions : 
21°30" | 37.4 78 0 0 0 0 0 | 0 
220 | 12h. {505 1244 496 192 IES OD 
22030’ | 110 | 454 1296 182 | 618 | 684 | 707 | 264 
2390’ | oi TLs nos Ss 623 748 339 
2400’ | 89 | 367 | 1046 620 | 489 540 | 642 290 
2500 Toet eae 928 B51 «| 433 419. | 567 | 257 
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