195 
vidual and the mean values of A and B are shown in the 
following table : — 
h . 
A 
Difference from 
Mean. 
B 
Difference from 
Mean. 
0 
11-71 
+ 1-04 
10-73 
r 2-41 
2 
11-61 
- j - 0'94 
11-04 
- 2-72 
4 
11-21 
+ 0-54 
9-96 
_ 
- 1-64 
6 
10-60 
—007 
8-40 
- 0-08 
8 
1052 
— 0-15 
7-26 
- 1-06 
10 
10-49 
— 0-18 
6-95 
- 1-37 
12 
10-24 
— 0-43 
6-97 
- 1-35 
14 
1011 
— 0-56 
6-96 
- 1-36 
16 
1009 
— 0-58 
701 
- 1-31 
18 
9-86 
— 0-81 
7-29 
-103 
20 
10-37 
— 0-30 
7-86 
- 0-46 
22 
11-22 
+ 0-55 
9-38 
+ 1-06 
Now if the view I took in my former paper is correct, and 
the mean daily movement of the wind is due to two forces, — 
one constant, or nearly so, both in direction and intensity, 
and the other constant in direction, but variable in intensity, 
and acting during only a portion of the day, then the sums 
of the differences in columns 3 and 5 of the above table, 
taken without reference to sign, will be the rectangular 
co-ordinates of the angle of direction, and total amount of 
movement caused by the action of the variable force. These 
sums are : — 
A differences = 6 To. 
B differences = 15-85. 
And the resulting angle of direction = 248° 48', and the 
total movement = 17'00 miles. 
The mean magnetic declination at Greenwich during the 
period of 1859-68 was 20° 46' W.; and as the declination is 
about 40' greater at Oxford than at Greenwich, the mean 
value for this period at Oxford would be 21° 46' W., or the 
angle of magnetic west would be 248° 34'. The calculated 
angle of direction of the disturbing force differs therefore 
only 14' from that of magnetic west. 
Deducting the sums of the A and B differences from the 
sums of the A and B values, we have the co-ordinates of the 
direction and movement of the wind due to the action of 
the constant force. These are 12T88 and 83 - 96, and the 
