Diurnal Variation of Temperature. 118 
ing the epoch of the maximum, it becomes evident that the 
assumption of an earlier maximum will remedy this defect,— 
and chiefly by increasing the importance and modifying the 
epoch of the second variable term. Thus putting H,=13" 44™ 
we find 
a=3°369, A=240° 42’, b=0°61, B=53° 57’ and the minimum at 
3" 36"; 
while for H,=13" 36™ we find 
a=3'368, A=240° 56’, b=0°63, B=54° 46’ and the minimum at 
35 56™. 
Plotting these curves we select the latter as possessing the more 
probable form of the two; thus giving, together with an abso- 
lute representation of the three fundamental observations, a 
curve of which the general form is normal and the epoch of 
minimum not improbable. These two conditions cease to exist 
when the assumed values of M and H, are much changed, and 
they fulfill approximately the function of that additional obser- 
vation which would permit the constants to be rigorously de- 
termined. 
the column 0:—C suffices to show how largely the residuals are — 
due to the neglected term depending upon 3h. 
Temperature. Temperature. 
Hour Poona ae 0—C Hour o—C 
Observed. | Computed. Observed. | Computed. 
10°79 10°41 | +0°38]| 13% 17°20 17°-25 | —0°-05 
2 10°49 10°23 +0°26 14 17°29 17-29 0 
3 10°29 10°18 +011 15 16°98 16-96 +902 
4 10°18 10°27 0-0 16 16°58 16°33 +0 25 
5 10°05 10°68 —0°63 17 15°95 15°50 + 0°45 
6 10-76 1112 0°36 18 14-76 14°56 +020 
7 11:90 11°90 0-00 19 13°51 13°64 0 
8 13-11 12°89 4+ 0°22 20 12°56 12°79 — 0°23 
9 14°26 13°99 +0°27 21 12-07 2-07 00 
10 15°30 15°10 + 0°20 22 LE67 |. 12°50 +0°17 
11 16°13 16°09 +0°04 23 11°33 11°03 +0°30 
ll 16°89 16°84 + 0°05 24 11-04 | 1068 +0°36 
The true formula as deduced from the hourly observations is 
T=13°38 43-536 sin (A +239° 33’) +0°645 sin (2A + 66° 1’) +0°365 
sin (3h+434° 31’) 
the corresponding maximum occurring at 13" 31", and the 
minimum at 3" 26", The mean error of the approximate form- 
ula is +0°-25, 
