1900-1901.] Prof. Knott on Solar Radiation. 
303 
The main features embodied in these numbers are indicated in 
the corresponding curves in the Plate, fig. 1. The well-known 
manner in which the crest of the temperature wave lags behind 
as the depth increases is evident at a glance, as also the rapidly- 
diminishing range of temperature. 
Each set of numbers was then treated by harmonic analysis, in 
accordance with the formula 
v= A 0 + Aj cos 0 + A 2 cos 20 + A 3 cos 30 + A 4 cos 40 + A 5 cos 50 + A 6 cos 60 
+ B x sin 0 + B 2 sin 20 + B 3 sin 30 + B 4 sin 40 + B 5 sin 50 + B 6 sin 60 
where v is the temperature, and the A’s and B’s constants to be 
determined by calculation from the twelve linear equations when 
for each value of the temperature given to v the corresponding 
value of 0 is inserted in the expressions on the right. Beginning 
with the value of 30° for October, 6 increases by 30 in each suc- 
ceeding month. The constants are tabulated below. 
Therm. 1. 
Therm. 2. 
Therm. 3. 
Therm. 4. 
A 0 
. 
45-358 
45-518 
45-8045 
46-257 
A x • 
+ 5-899 
+ 5-304 
+ 2-672 
+ 0-156 
B x • 
-4-447 
-2-400 
+ 0-728 
+ 0-886 
a 2 . 
+ 0*21 
+ 0-278 
+ 0-2145 
+ 0-0053 
b 2 . 
-0-8983 
-0-572 
-0-048 
+ 0-0462 
A 3 
-0-1157 
-0-125 
-0-0408 
+ 0-0047 
b 3 . 
+ 0-3373 
+ 0-227 
-0-0055 
+ 0-0107 
a 4 . 
-0-0045 
+ 0-0435 
+ 0-0238 
+ 0-0057 
B 4 ■ 
+ 0-043 
+ 0-0738 
+ 0-0033 
+ 0-0042 
Ag 
+ 0T267 
+ 0-0558 
+ 0-0082 
+ 0-009 
B 5 . 
-0-0872 
-0-0305 
+ 0-0073 
+ 0-0028 
Ag 
+ 0-0123 
+ 0*017 
+ 0-0207 
+ 0 010 
B 6 . 
0 
0 
0 
0 
Most information is obtained from the first and second harmonic 
terms in each. According to the recognised theory, it should be 
possible to combine the first harmonic terms in the formula 
