104 Daniell on Meteorological Observations. 



to water ; which is at one time converted into vapour, perma- 

 nent as a part of the atmosphere for the season ; at another 

 dismissed in rain. In elucidating this connexion he continues, 

 " Now in the brumal quarter, where we find the average of the 

 barometer lowest, the temperature is lowest also ; and there is 

 every reason to conclude that the atmosphere in our district, 

 and for many degrees of latitude and longitude around us, 

 contains at this season, the lowest proportion of ponderable 

 vapour." But this reasoning does not agree with the fact 

 which he had just before stated ; namely, that the average of the 

 barometer is lowest in the autumnal quarter. Neither is the 

 amount of this difference nearly sufficient to identify it with 

 that of the vapour: it does not reach 0.1* inch while the 

 excess of the summer vapour over the winter exceeds 0.2 

 inches. Moreover, if this influence were really appreciable in 

 this manner, it is one of so constant a nature as must have 

 shewn itself invariably in every recurrence of the seasons, not 

 requiring to be elicited by a long series of averages. 



But that there is a connexion between the great fluctuations of 

 the" atmosphere and the vapour which it contains at least in its 

 precipitation, is evident from the following fact : of 674 observa- 

 tions of rain, hail, and snow, during the two years, only .94 took 

 place, while the barometer was above the average of the season 

 as deduced in Table 2. Of these 94 the greater part were 

 very partial showers, chiefly in the winter quarters. Of the 

 general results of the barometer alone, I shall not attempt to 

 speak : the subject has been so ably elucidated by Mr. Howard, 

 with such ample provision of observations, that it would be 

 presumption in me to follow him, especially with such short 

 experience. I am happy to observe that the mean of both 

 years' observations agree with the mean as deduced by him for 

 London : those periods where I differ, I consider as only oscil- 

 lating round the true point, to which in a series of years they 

 will be amenable. 



The variations in the quantity and pressure of the aqueous 



* In Mr. Howard's work, Vol. II., page 281, this difference is misprinted 

 0.96 inches for .096. 



