1890 - 91 .] Dr A. Buchan on Diurnal Barometric Curves. 61 
Greenwich. 
Kew. 
Difference. 
7 A.M. 
+ 59 
+ 79 
20 
8 „ 
+ 85 
+ 99 
14 
9 „ 
+ 87 
+ 87 
0 
10 „ 
+ 91 
+ 67 
-24 
11 „ 
+ 67 
+ 45 
- 22 
Noon. 
+ 17 
- 7 
-24 
This comparison has been made for the whole year, and the differ- 
ences are entered in their places in the accompanying Table, where 
the minus sign indicates that, at the hour specified, Kew was that 
amount relatively lower with respect to its daily mean than Green- 
wich was with respect to its daily mean, and the plus sign that it 
was relatively higher. 
A longer period of comparison between these two barometers than 
five years will doubtless give still smoother curves than the Table 
indicates. Meantime, it is very evident that the ordinary diurnal 
barometric curve at Kew has superimposed on it a strongly marked 
curve, due to the relatively low position of the Observatory in the 
valley of the Thames. 
Table showing Comparison of Kew and Greenwich Barometers 
in Ten-thousandths of an Inch. 
Jan. 
Feb. 
Mar. 
Apr. 
May 
June 
July 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 
Year. 
1 A.M. 
- 2 
0 
+11 
+ 6 
+ 5 
+28 
+ 17 
+ 8 
+ 9 
- 2 
- 5 
- 2 
+ 6 
2 „ 
0 
- 1 
+ 8 
+ 6 
+13 
+26 
+24 
+ 18 
+14 
+ 3 
- 7 
+ 8 
+10 
3 ,, 
+ 2 
- 3 
+ 5 
+ 3 
+11 
+28 
+ 25 
+20 
+ 19 
- 7 
-12 
0 
+ 8 
4 „ 
+ 2 
-12 
+ 9 
+ 5 
+ 9 
+24 
+ 21 
+30 
+ 13 
+ 15 
- 7 
-11 
+ 8 
5 „ 
- 5 
-13 
- 3 
- 1 
+17 
+26 
+23 
+15 
+ 8 
+ 7 
- 6 
-14 
+ 5 
6 „ 
- 7 
-13 
- 3 
+ 7 
+22 
+30 
+29 
+28 
+21 
+14 
- 1 
- 3 
+ 11 
7 ,, 
- 9 
- 1 
- 5 
0 
+22 
+20 
+24 
+ 15 
+11 
- 1 
- 3 
- 5 
+ 5 
8 „ 
-10 
+11 
- 8 
- 1 
+16 
+14 
+18 
+ 15 
+ 9 
+ 3 
+10 
1 
+ 8 
9 », 
-15 
+11 
+ 3 
- 3 
+ 6 
0 
+ 5 
+ 1 
+ 7 
+ 7 
+ 6 
13 
+ 1 
10 „ 
- 1 
+ 7 
+11 
-11 
-10 
-24 
- 8 
- 5 
- 5 
- 9 
+ 8 
+ 4 
- 4 
11 „ 
+ 1 
+13 
+ 7 
- 8 
-13 
-22 
-16 
-10 
+13 
+ 1 
+ 9 
+ 8 
- 1 
Noon. 
+ 12 
+ 3 
- 9 
-18 
-23 
-24 
-16 
- 7 
+ 3 
- 3 
- 4 
- 8 
- 6 
1 P.M. 
+ 6 
+ 5 
- 9 
-10 
-17 
-16 
-18 
-16 
- 1 
- 3 
- 5 
+ 2 
- 7 
2 „ 
-18 
-15 
-27 
-36 
-45 
-38 
-36 
-27 
-17 
- 9 
-10 
-16 
-25 
3 „ 
-17 
- 7 
-13 
-12 
-33 
-26 
-20 
-22 
— 23 
-11 
-15 
-12 
-18 
4 „ 
—15 
- 9 
-15 
-21 
— 36 
-36 
-34 
-33 
-29 
- 5 
- 8 
- 4 
-20 
5 „ 
-17 
- 7 
- 9 
-19 
-24 
-28 
-23 
-35 
-17 
-11 
-10 
-12 
-19 
6 „ 
+10 
+ 1 
-17 
- 5 
-18 
-24 
-28 
-25 
-17 
- 7 
- 2 
- 1 
-12 
7 „ 
+ 5 
+ 3 
- 3 
+16 
- 2 
-16 
-24 
-11 
-17 
- 3 
+ 9 
+ 5 
- 4 
8 „ 
+17 
+11 
+ 5 
+ 23 
+ 14 
+ 8 
- 1 
- 2 
- 1 
+ 8 
+19 
+ 9 
+ 8 
9 „ 
+17 
+11 
+11 
+23 
+ 15 
+ 6 
+ 3 
- 3 
- 4 
+ 5 
+10 
+22 
+ 9 
10 „ 
+ 18 
+ 8 
+ 11 
+ 27 
+25 
+10 
+ 9 
+ 8 
+11 
+ 5 
+15 
+ 17 
+12 
11 „ 
+12 
+ 3 
+13 
+ 5 
+21 
+10 
+13 
+10 
- 1 
- 1 
+ 8 
+10 
+ 8 
Midnight. 
+ 2 
+ 7 
+ 12 
+ 8 
+15 
+16 
+14 
+ 8 
+ 2 
+13 
+11 
+16 
+ 9 
