Peessure and Dieection of the Wind. 
ci 
212. The following numbers are the ratios for eacli second liour of the hourly mean pressures observed 
iu all directions (obtained from the year-column of Table 92, by the addition of 0-46, the mean pressure for 
the 4 years), to the resultant mean pressui-es, No 210. 
IS'' 2^ A.M. 6^ 8^ 10^ 0^ 2^ P.M. 41" 6i> 8^ 10^ 
2-1 2-1 2-1 2-3 2-3 2-4 2-6 2-8 2-9 2-8 2-4 2-2 
We may conclude, as in No. 209, that of the total mass of air in motion at each hour, the greatest proportion 
was from the same quadrant or direction at 2'' a.m., and the greatest proportion was from opposite directions 
at 4*" P.M. 
213. Times luhich the Wind blew from the 16 Principal Points of the Compass. — The times which the 
wind was observed blowing from each point of the compass, at the observation hours, are given for each year 
in the previous and in the present volume; for 1843 and 1846 the sums for 12 two-hourly observations are 
given, having doubled these to make them comparable with the means from the hourly observations of 1844 
and 1845, the sums for four years for each point were obtained : the sums for each of the 16 principal points 
were then formed in this manner ; — the sum of the times in the north was made equal to half the sum of the 
times in N by W., plus half the sum of the times in N by E., plus the sum of the times observed in N. ; and 
similarly for each of the other 16 points.* The sums thus obtained from the four years' observations are as 
follow : — 
N. NNE. NE. ENE. E. ESE. SE. SSE. S. SSW. SW. WSW. W. WNW. NW. NNW. 
779 1318 1668 867 431 177 329 575 1088 2672 4212 1949 1198 726 932 866 
The wind blew most frequently with a pressure of 0-1 lb., or upwards, from a few degrees south of SW., the 
number of times diminishes rapidly to WlSfW., increases slightly in NW., diminishes from thence to N., it then 
increases considerably to a few degrees north of NE., where the secondary maximum occurs almost diametri- 
cally opposite to the principal maximum of frequency ; from NE. the frequency diminishes to a few degrees 
south of ESE., where it is a principal minimum, a secondary minimum occurring in the opposite point ; from 
ENE. the number increases rapidly to the maximum at SW. See curve h in the figure. 
Radial scales, a, 1 inch = 2000 lbs. h, 1 mch = 2000 times, c, 1 inch= 1 lb. 
* The combination into the 16 principal points was rendered necessary by the fact, that in observing the direction of the wind 
from an oscillating vane-index, there is a tendency in all cases of doubt to prefer the principal to the secondary point, for which 
reason the numbers of observations for each of the 16 principal points were always greater than for either of the two adjacent points. 
