EXPOSURE. 27 



upon fruit cultivation. For instance, while some 

 varieties of grapes will not ripen if exposed to the 

 north or west, they mature quite early on a south- 

 ern or eastern slope. Therefore, if an isothermal 

 line is to be an infallible guide, it should run down 

 on the latter, and up on the former. Some slopes 

 are open to furious and chilling winds from the cold 

 regions, which tend to depress the line. 



These are among the more general facts to be 

 considered. It can readily be seen that perfect ac- 

 curacy must be practically impossible. The culti- 

 vator must exercise a wise judgment with regard to 

 these principles, or his efforts will not be crowned 

 with complete success. 



Among the more general facts which should 

 guide us in determining the limits of the successful 

 cultivation of different fruits, and the proper selec- 

 tion of exposure for each variety, let us notice the 

 effects of lar(je^ contiguous bodies of water ; or the 

 difference between island or coast, and inland or 

 continental climate, — a difference which is very 

 striking in respect to the limits of cultivating a 

 particular plant. This is owing to the greater ease 

 with which land rather than water absorbs and radi- 

 ates heat. Land becomes w^arm much sooner, but 

 falls in temperature with equal rapidity. On the 

 contrary, the sea is not so soon heated, on account 

 of its brilliant surface, which reflects the rays of the 

 sun ; neither is it so soon cooled, owing to the great 



