428 
MR. LOUIS VESSOT KING ON THE SCATTERING AND 
Diagrams IX. and X.— Total Badiation Calculated from Mount JFilson and JFashmgton Observations. 
The curves drawn on Diagrams IX. and X. are drawn from the data calculated in Tables VII. and IX. 
for the values of total solar and sky radiation at Mount Wilson and Washington respectively. The 
various curves denoted by L, II., III., IV., refer to the following quantities:— 
Curve 1. gives the total intensity of solar radiation in calories per square centimetre per minute normal 
to the sun’s rays ; i.e., the curve represents the variation of 
E (0 dX with (. 
Curve 11. gives the total intensity of solar radiation in calories per square centimetre per minute on a 
horizontal plane; i.e., the curve represents the variation of 
cos I E (0 dX with (. 
Curve III. represents the total intensity in calories per square centimetre per minute of the radiation 
from the entire ski'^ on a horizontal plane; i.e., the curve represents the variation of 
j" H (0 dX with 
Curve IV. represents the total radiation from sun and sky on a horizontal plane; i.e., the curve 
represents the variation of 
{cos (E (0 + H (()} dX with (. 
The calculations are oidy given as far as ^ = 80°. Curves I. and II. fall to zero at f = 90°. Curve III. 
is arbitrarily carried on beyond this point (in dotted lines) to ^ = 100°, and represents to some extent the 
intensity of scattered radiation due to the “ twilight ” following the sunset or preceding the sunrise. The 
effect of the earth’s curvature makes it practically impossible to calculate the scattered radiation when the 
sun is below the horizon. The heat reaching the earth before sunrise shows itself in continuous air- 
temperature records in the fact that the minimum in the diurnal inequality of temperature occurs about 
one-half hour before the sun actually rises. 
The curve just described are intended for use in meteorological problems. 
