328 Mr. Hinds on Climate in connexion 



Between the amount of evaporation and precipitation there 

 is necessarily a considerable connexion ; this is observable in 

 the quantity of rain in different latitudes, and again in our own 

 climate, where more rain falls in the warm than in the cold 

 seasons ; towards the end of our simimer the amount is 

 greatest ; and of two summers, one cold and the other conspi- 

 cuous for its warmth, the latter closes with most rain. No 

 regular proportion exists between the number of rainy days 

 and the quantity of rain. In noting the rainy days of a 

 climate, it is usual to enumerate every day of the year on 

 which even a slight shower has been observed. The number 

 of days on which rain falls depends much on the range of 

 temperature which takes place in short intervals of time, par- 

 ticularly in extra-tropical latitudes, and if the atmosphere re- 

 ceives its moisture from the ocean, the number will be much 

 increased. These days are more numerous as we advance to 

 high latitudes, and are thus inversely to the amount of rain. 

 In the table the general progression of both is visible. 



There is a feature in the fall of rain, which, though inti- 

 mately connected with elevation, we do not think is very 

 likely to influence alpine vegetation ; yet as it may in some 

 cases contribute to account for any peculiarities this variety of 

 flora may possess, we cannot pass it over without some notice ; 

 to the meteorologist it is of greater interest. Many years 

 since it was ascertained, that if rain was collected at different 

 elevations in the same perpendicular, a difference in the 

 amount would be observed ; that the portion nearest the 

 surface Avould be greatest, and on increasing the height a 

 gradual diminution would take place. Experiments were 

 made at several places, and all with the same results. The 

 Hon. Daines Barrington measured the quantity in Wales 

 between the base and summit of a mountain 1850 feet high; 

 in four months 8*766 inches had fallen below, and on the 

 height 8'165 inches. Dr. Heberden obtained the same re- 

 sults, but in more decided proportions ; and more recently 

 some observations have been conducted at York by Messrs. 

 Gray and Phillips, which give the amount at three separate 

 heights. The particular situation of the observations, height 

 and quantity of rain, are as follows : — 



Top of Minster, elevated 242 feet, 15-715 inches. 

 Top of Museum, „ 73 „ 20-182 „ 



Grounds of Museum „ 29 „ 23-785 „ 



To account for this increase, it has been advanced, that the 

 drops of rain in they' descent, owing to their lower tempera- 

 ture, condense around them the aqueous vapour in the atmo- 

 sphere through which they pass. 



