dr. a. a. eambaut on underground temperature at oxford 
252 
From the monthly means given above, we deduce the following :— 
Values of the Coefficients. 
No. 
«o 
h 
a-2 
h 
Pi 
Ei 
P 2 
e 2 
5 
4 
3 
2 
1 
Air 
o 
52-005 
52-189 
52-224 
52-013 
52-010 
50-396 
o 
- 1-970 
- 6-379 
- 9-467 
- 12-932 
- 15-337 
-12-776 
o 
-4-706 
-5-318 
-4-725 
-3-128 
-1-507 
- 1-621 
o 
-0-068 
+ 0-661 
+ 1-370 
+ 2-130 
+ 3-017 
+ 2-817 
o 
+ 0-537 
+ 1-029 
+ 1-123 
+ 0-976 
+ 0-511 
+ 1-410 
o 
5-102 
8-305 
10-581 
13-305 
15-411 
12-878 
o / 
202 42-8 
230 10-9 
243 28-6 
256 24-3 
264 23-2 
262 46-1 
o 
0-541 
1-223 
1- 771 
2- 343 
3- 060 
3-177 
o / 
352 45-1 
32 42-1 
50 39-5 
65 23-3 
80 23-2 
63 39-2 
In this table I have added, for comparison, the constants of the Fourier series 
representing the mean temperature of the air in the Stevenson screen at a height 
of 4 feet above the surface, deduced, as has been the custom for many years at this 
Observatory, from observations of a standard mercury thermometer at 8 A.M., noon, 
and 8 p.m. 
Some interesting results appear at once from this table. As was to be expected 
the mean temperatures (denoted by « 0 ) of the soil at all depth exceeds that of the 
air, although the differences are less than those deduced by Professor Everett from 
the Greenwich results for thirteen years. # It will also be noticed that the annual 
range of temperatures for Nos. 1 and 2 exceeds that of the air. This is only true of 
the monthly means. The range of the mean diurnal air temperature is considerably 
greater than that observed for any of the underground thermometers. The maxima 
and minima are given in the following table :—• 
Thermometer. 
Maxima. 
Minima. 
o 
O 
Air 
75-4 
21-1 
1 
75-29 
33-48 
o 
jU 
70-03 
36-97 
3 
65-28 
41-45 
4 
62-28 
44-38 
5 
57-96 
47-08 
If the actual maximum and minimum for the air had been taken instead of the 
daily mean, the range would have been even greater. 
I have not taken into account the terms depending on 3b For No. 5 this term is 
0°-256 sin (3 \t + 117° 28'), 
and in the case of the other thermometers they attain slightly larger dimensions; 
* ‘.Greenwich Observations,’ I860 (cxciii.). 
