It appeal’s therefore that in the years of maximum solar 
spot frequency the maximum barometric pressure took place 
under north-east winds, and the minimum under south- 
west; but in years of minimum frequency the maximum 
and minimum pressures occurred respectively under north 
and south-east winds. The difference of pressure under 
north-west winds is almost inappreciable; and the differ- 
ences under north and south winds are small ; but those 
under north-east, east, south-east, south-west, and west 
winds are too considerable to be fairly attributable to acci- 
dental causes. In order then to determine whether they 
are due to the operation of a change in the intensity of solar 
activity I have made the following comparison of the mean 
pressures under north-east, east, and south-east winds with 
those under south-west and west winds : — 
Mean Pressure Mean Pressure 
under winds from under winds from 
N.E., E., & S.E. S.W. & W. 
In. In. 
Difference. 
Inch. 
1858 . 
29-848 .. 
.... 29-649 
+ -199 
1859 . 
29-813 .. 
.... 29-672 
+ -141 
18G0 . 
29-728 .. 
.... 29-502 
+ -226 
1861 . 
29-775 .. 
.... 29-714 
+ -061 
1862 . 
29-756 .. 
.... 29-683 
+ -073 
1863 . 
28-794 .. 
.... 29-782 
+ -012 
1864 . 
29-673 .. 
.... 29-717 
- -044 
1865 . 
29-715 .. 
.... 29-722 
- -007 
1866 . 
29-664 .. 
.... 29-717 
- -053 
1867 . 
29-685 .. 
.... 29-835 
- -150 
1868 . 
.... 29-757 .. 
... 29-748 
+ -009 
The maximum difference 
occurred in 1860, 
when solar 
spot frequency was at a maximum, and the minimum differ- 
ence in 1867, when solar spot frequency was also at a 
minimum, and the general course of the differences has a 
remarkable similarity to that of the numbers representing 
the variations of solar spot frequenc}^. 
As the rate of variation in the pressures during the 
maximum years 1858-62 was greatest in the quadrant 
between north-west and south-west, and as winds from 
the westward coming over the Atlantic are probably less 
