IV. CLIMATE. 105 



2. Assuiiud altitude for different temperatures. 



relations, or to compare the climatal places of diiferent 

 species together, some such scales as here proposed be- 

 come indispensable. For example, let it be supposed 

 that one species of plant ascends to 600 j'^ards of eleva- 

 tion in North Wales, in latitude 53 ; also, that another 

 species ascends to 400 j-ards on the hills of Scotland, in 

 latitude 57. It is wished to determine which of these 

 two species should be placed above or below the other in 

 a series arranged according to relations with climate, so 

 far as those relations arise from or correspond with mean 

 temperatui'e. The height of 600 yards in latitude 63 

 corresponds with the temperature of 6.4 in the first table; 

 and the height of 400 yards in latitude 57 corresponds 

 with the temperature of 6.2 in the same table. Conse- 

 quently, the species of Scotland is deemed to ascend into 

 an inferior or colder climate than the sijocies of Wales, 



