180 



Mr. Hinds on Climate in connexion 



Juniperus, and Betula. At San Francisco in California, in 

 38° N. lat., the open forest of this fine country is composed 

 of trees of Quercus, four species, two deciduous, two evergreen ; 

 Fraxinus ; Platanus ; Salix, several species ; Pavia ; Popuht* ; 

 Betula ; Juglans ; and often an abundant undergrowth of va- 

 rious shrubby Composite. Finns rigida grows at the level of 

 the ocean, and P. religiosa on the elevated land. In Europe 

 we can ascend several degrees of latitude higher and still be 

 surrounded by a milder vegetation, though the Alps present 

 a natural and stupendous barrier to the diffusion of the 

 southern flora. The vegetation is everywhere open, and large 

 trees unfrequent ; its larger members belong to Quercus, se- 

 veral evergreen species ; Phillyrea ; Buxus ; Cistus, numerous 

 species ; Pistacia, and Paliurus. The ash meets too warm a 

 temperature below 41°; oranges and olives are cultivated in 

 great abundance. Chamcerops has in Europe a representative 

 as far north as 44°, whilst on the eastern coast of North 

 America a near relative is limited to 36°. Some species of 

 Pinus are found throughout Spain, and on its Mediterranean 

 shores P. halepensis and P. pinea flourish. 



Asia partakes of the features of America in a comparison 

 with Europe. Quercus robur ceases 2° further south, and grows 

 but sparingly below this. Barley is not cultivated nearly so 

 far north as in Europe; Pinus sylvestris does not venture 

 near the arctic circle, and many of the forest trees common 

 to both are all more or less circumscribed by a less favourable 

 climate. Towards Europe the vegetation of Asia becomes im- 

 perceptibly blended with that of the former. In the north-west 

 part of Europe the climate is severer, and resembles closely 

 the Asiatic ; on this side it is invested by mountain ranges, 

 and the cold winds blowing from them are piercing, and con- 

 trast strongly with the hot winds of the south, and the moist 

 westerly breezes from the Atlantic Ocean. 



The disparity in the temperature of the northern and south- 

 ern hemispheres also originates in the equalizing power of the 

 ocean. In the southern the proportion of water to land is 

 greatest; within the tropics there is no great difference, 

 but beyond them it becomes important, and as there is here 

 no great extent of dry land, the climate possesses in many 

 respects the character of an island-climate. To say that one 

 hemisphere is hotter or colder than the other, is not express- 

 ing the actual condition of either ; one possesses a continental 

 climate, or a climate tending to extremes ; the other an island- 

 climate, or one limited in its range of temperature. The 

 summers of the extra-tropical regions of the southern hemi- 

 sphere are not so warm, nor the winters so cold, as in the 



