26 Proceedings of Royal Society of Edinburgh. [dec. 6, 
upper thermometer reads distinctly above the lower, from noon to 
sunset distinctly below it, and during the night slightly above it 
again. An examination of the black bulb temperatures for these 
two days shows nothing calling for special note. The range is greater 
than in the monthly average, but the curve is substantially the 
same, except for a slight lagging of the maximum point, but the 
Hours. 
Black Bulb in 
vacuo. 
Temp. 48 inches 
above ground. 
Temp. 112 inches 
above ground. 
Diff. of high from 
low temp. 
Mean diff. of 2 
fine days. 
Mean diff'. of 9 
foggy days. 
Mclnt. 
38*8 
39-2 
39 '4 
+ 0-2 
+ 0-2 
+ 01 
1 
387 
39T 
39-2 
+ 0T 
+ 0-2 
+ 07 
2 
38-4 
38-8 
38-8 
o-o 
+ o-i 
o-o 
3 
38-4 
38-7 
38-8 
+ 0 T 
o-o 
o-o 
4 
38-1 
38-5 
38-6 
+ 0*1 
+ 07 
+ 07 
5 
38-8 
38*4 
38*5 
+ 0T 
+ 0-7 
o-o 
6 
43-6 
38-4 
38-6 
+ 0-2 
+ 2*1 
o-o 
7 
47-4 
38-9 
39-0 
+ o-i 
+ 1-0 
o-o 
8 
53 '6 
39-2 
39-2 
o-o 
+ 0-6 
o-o 
9 
57*9 
39-6 
39-5 
-01 
+ 0-4 
o-o 
10 
60-7 
39-8 
39-8 
o-o 
+ 0-6 
-07 
11 
64-5 
40-3 
40-2 
-0T 
+ 01 
-0-2 
12 
67-0 
40-9 
407 
-0-2 
o-o 
-01 
13 
64*3 
41-3 
41 T 
-0-2 
-0-3 
-07 
14 
62*3 
417 
41-5 
-0-2 
-07 
- 0'2 
15 
62-2 
41-8 
41*7 
-0T 
-0-6 
o-o 
16 
58-1 
42-0 
41-8 
-0-2 
-1-0 
-o-i 
17 
52*5 
417 
41-6 
-0T 
-0*4 
0-0 
18 
46-8 
41-2 
41-2 
o-o 
+ 07 
o-o 
19 
43*1 
407 
407 
o-o 
+ 0-2 
o-o 
20 
407 
40-6 
40-6 
o-o 
0-0 
+ 0-1 
21 
39-9 
40-4 
40-5 
+ 0-1 
+ 0-4 
+ 0*1 
22 
39-8 
40-3 
40*4 
+ 0T 
i-0‘3 
o-o 
23 
39-5 
39-9 
40-0 
+ 0T 
+ 0*2 
+ 07 
Mdnt. 
39 '2 
39-6 
39*7 
+ 0T 
o-o 
+ 01 
Mean. 
49*0 
40 T 
40T 
o-o 
period is too short to say anything definite about this. As a 
contrast to these fine days, I have computed the mean differences 
on nine days of continuous fog or mist. These differences are 
given in column six of the table, and are shown by the line in the 
lower part of the diagram with the least range. Here, though 
there is still a tendency of the upper thermometer to read higher 
at night and lower in the afternoon, the differences are very small ; 
