118 ABNORMAL VARIATIONS AT TORONTO. 



liours of the greatest and least pressure included among the six hours 

 of observation. 



The mean extent of the oscillations at 2^ and -^ are found to be 

 greater than at lO*", 12^ IS**, and 20'' in every month but January and 

 Februarv, and in each quarter, excepting the winter. 



From table XXV. it appears that the pressure of vapour is below 

 the normal when the wind at the time of observation is from N., N.W., 

 and W., and above it when the wind is from any other quarter. It 

 has also been found that with winds from N., N.W., and W. the 

 pressure of vapour is below the normal in every month, with two 

 exceptions out of thirty-six, and that in every month with winds from 

 the other points the pressure is above the normal, with seventeen 

 exceptions out of sixty. 



The mean changes of the pressure of vapour in twenty-four hours, 

 for each of the three years, and for each month in the average of the 

 three years, are given in tables XXVI. and XXVII. 



The quarterly means given are 0.044 in spring, 0.087 in summer, 

 0.067 in autumn, and 0.042 in winter ; the general mean being 0.060, 

 which is slightly less than the general mean abnormal variation. 



From table XXVI. it appears that a resultant wind from N., N.W., 

 and "W. is accompanied by a diminished pressui'e of vapour, and that 

 with a resultant wind from any other quarter the pressure of vapour 

 is increased. With very few exceptions this has been found to be true 

 for each month taken singly as well as on the average of the year. 



With a view of shewing more distinctly the shares taken by the 

 pressures of dry air and of vapour in producing the varied conditions 

 of the barometer that accompany the different winds ; the abnormal 

 variations of the barometric pi'essure and of the pressures of dry air and 

 of vapour, as well as the changes between 6 a.m. and 6 am., corres- 

 ponding to the eight principal points of the compass, have been collected 

 in tables XXVII. and XXVIII. 



RELATIVE HUMIDITY. 



On the average of the three years the abnormal variation of relative 

 humidity is 9.4, saturation being 100 : the greatest monthly value 

 is'12.3 in June, and the least 8.0 in December and January. 



Of the six observation hours, 4 p. m. and 6 a. m. are the hours most 

 subject and least subject to irregularity. 



