ON THE METEOROLOGY OP TORONTO IN CANADA. 



49 



is partly obscured by other less direct influences of the temperature. Thus 

 at Trevandruni, in the East Indies, where the zeal of our indefatigable 

 associate Mr. Caldecott, Director of the Magnetical and Meteorological Ob- 

 servatory established by His Highness the Rajah of Travancore, has already 

 accumulated, reduced, and transmitted to England five years of hourly obser- 

 vations with the wet and dry thermometers, the maximum and minimum of 

 the tension are found to occur within three hours of each other ; the mini- 

 mum coinciding with the coldest hour, viz. at 6 a.m. ; but the maximum 

 occurring at 9 in the forenoon. This may possibly be a consequence of the 

 sea breeze, which springs up as the sun gains power, and as the earth warmed 

 by the solar rays heats the air in contact with itself and causes it to rise, occa- 

 sioning an inpouring of the air from over the surface of the ocean. The sea 

 breeze brings an influx of fresh air charged with vapour ; the air in its turn 

 is heated and ascends, but the vapour is subject to a difierent law ; and though 

 a portion of it is doubtless rapidly conveyed upwards by the ascending cur- 

 rent, it is probably the accumulation below which causes an immediate rapid 

 rise in the tension of the vapour, making its maximum to occur at a very early 

 hour. The few facts which are yet known regarding the diurnal march of 

 the vapour in different parts of the globe, present many phsenomena of this 

 nature, which at first sight appear inconsistent with the dependence of the 

 progression of the vapour on that of the temperature ; but which, when duly 

 explained, will doubtless be found directly or indirectly in accordance with it. 

 The knowledge of the phsenomena of the vapour in different climates and 

 under different circumstances (such as in insular, littoral, or continental 

 situations, &c.), with the explanation of the various peculiarities which they 

 present, will form hereafter a very interesting and beautiful chapter in the 

 physical history of the globe. 



Annual Variation, — We will now proceed to the mean montldy humidity 

 and mean monthly tension exhibited in the following tables : — 



Mean Monthly Humidity. 



We perceive by the table in which the mean monthly humidity is shown, 

 that the months from March to July are drier than the average of the year, 

 and that the remaining months are more humid than the average. The drier 

 months are those in which the temperature of the air is rising ; the most hu- 

 mid those in which the temperature is eitherfalling or nearly stationary. When 

 the temperature is rising the warmth increases more rapidly than the air re- 



1844- E 



