38 



RESULTS OF METEOROLOGICAL OBSERVATIONS 



The mean effect is expressed by the formula 



T:=i — 1.°2 + 5.0 sin {d + 281°) + l°.l sin {2d + 64° 

 where 6 counts from the north in the direction north, east, etc. The observed and 

 computed values compare as follows : — 



Direction. 



Observed. 



Computed. 



0— c. 



N. 



— 4°.3 



— 5°.l 



+0°.8 



N. E. 



—4.7 



—3.5 



—1.2 



E. 



— 0.2 



—1.2 



+1.0 



S.E. 



+1.8 



+2.5 



—0.7 



S. 



+4.9 



+-1-7 



+0.2 



s.w. 



+2.2 



+2.1 



+0.1 



w. 



—3.0 



—3.1 



+0.1 



N. W. 



—6.2 



—5.8 



—0.4 



Relation of Direction of Wind to Rain. 



To ascertain the relative amount of rain observed or to be expected for each 

 direction of the wind, the latter was tabulated for all the rainy days during 22 years 

 (1829 to 1850). Dividing the year in two equal parts, one including summer 

 (April 15 to Oct. 15), the other winter (Oct. 15 to April 15), we have in the first 

 1018 days, and in the second 803 days on which rain fell, and the corresponding 

 relative frequency of each direction of the wind for the two seasons is given in 

 column 2 of Table VIII. As each wind does not occur the same number of times 

 in any given period, the above numbers, to reduce them to a common measure, 

 must be divided by the relative frequency of each wind (made out from Table VI). 

 These numbers are given in column 3, and the ratio in column 4. The relative 

 frequency of rain and wind is expressed in percentage. 



Table VIII. 





Summer. 





Winter. 





Direction of 

















1 







Relative frequency 



Relative frequency 

 of wind. 



Eatio. 



Relative frequency Relative frequency 

 of rain. | of wind. 



Ratio. 



s. 



22 



2a 



1.1 



14 



14 



1.0 



s.w. 



31 



21 



1.5 



19 



22 



0.8 



w. 



13 



10 



1.3 



18 



17 



1.0 



N.W. 



6 



7 



0.9 



11 



11 



1.0 



N. 



12 



24 



0.5 



17 



20 



0.8 



N. E. 



3 



4 



0.8 



3 



4 



0.7 



E. 



4 



5 



0.8 



7 



5 



1.4 



S.E. 



9 



9 



1.0 



11 



7 



1.5 



During the summer, therefore, the directions from which most rain comes are 

 S., S. W., and W., the S. W. wind bringing relatively the maximum amount ; in 

 winter these directions are E., S. E., and S., the S. E. wind bringing relatively the 

 maximum amount. Rain rarely comes from the northward in summer or winter. 



Relation of the Direction of the Wind to Fair Weather. 



The same process of investigation being pursued as above, the result of a tabula- 

 tion of the winds on days of fair weather during summer and winter for the years 



