ON THE METEOKOLOGY OF TORONTO IN CANADA. 



53 



neral in its application. I have inserted in the table the gaseous pressure 

 at Prague, as it is given by M. Kreil in his ' Jahrbucli' for 1843, from the 

 observations of three years. The march of the vapour, as far as it has yet 

 been determined at Prague, does not present a curve agreeing quite so satis- 

 factorily with that of the temperature as we have been able to deduce at 

 Toronto: whether this arises from disturbing influences in nature (such 

 possibly as indirect influences of temperature), or whether it will disappear 

 by longer-continued observation, cannot be yet anticipated. What is still 

 uncertain, however, at Prague, is not of magnitude sufficient to obscure the 

 dependence of the annual progression of the gaseous pressure on that of the 

 temperature. The measure of agreement in this respect at the two stations 

 cannot be viewed otherwise than as highly interesting and satisfactory. 

 Mean quantities derived from a greater number of years will in all proba- 

 bility show even a closer accordance. 



We will now revert to the maximum, minimum and range of the vapour 

 pressure in the several months of the year, for the purpose of showing that 

 its variations are such, as to seem to claim a greater attention than they have 

 hitherto received, at the hands of those who are engaged in investigating the 

 non-periodic fluctuations of the atmosphere, by the comparison of observed 

 barometrical heights. In the next table we have the maximum, minimum, and 

 range of the vapour pressure at Toronto, taken from the mean of two years. 

 By thus exhibiting the mean quantities only of the two years of observation, 

 extremes are of course somewhat moderated ; but, on the other hand, there 

 is the advantage that the numbers are probably a more faithful representation 

 of what may be expected in ordinary course. 



We here perceive that the mean monthly range of the tension of the 

 vapour falls little short of four-tenths of an inch ; and that in the summer 

 months of June, July, August, and September, when it is greatest, it is very 

 little less than the whole range of the barometer in the same months. Win- 

 ter is the season for the great fluctuations of the barometer ; summer for those 

 of the vapour pressure. If, as is believed by many modern meteorologists, 

 the fluctuations of the vapour pressure affect the barometer to their whole 

 extent, then the fluctuations of the gaseous atmosphere at Toronto approach 



