LIMITS OF THE VINE. 37 



It is often noticed that the sweetest fruits are 

 nearest to the ground, because they obtain a greater 

 amount of heat by its radiation from the earth. Mr. 

 Murray, of England, proved that this was very dif- 

 ferent on the side of a hill from what it was in the 

 valley. In one case the thermometer was thirty de- 

 grees higher on the inclined surface than in the 

 plain. He states that upon the plains of Piedmont, 

 in Italy, the vignerons are obliged to detach their 

 vines from the poles, and cover them during the 

 winter, to prevent injury ; while on the acclivities 

 which surround the city of Genoa, the pomegranate, 

 the lemon, and the orange, flourish. 



The principles of radiation were understood in 

 very ancient times. In the land of Judea the vine- 

 yards and orchards were often planted upon terraces, 

 to acquire additional heat. 



In Europe they fixed the limits of the vine by the 

 mean temperature of the summer months. The 

 least mean degree required for the ripening of grapes 

 suitably for wine is sixty-seven degrees. Boussin- 

 gault thus states the effects of the temperature upon 

 the quantity and quality of wine produced.^ (See 

 Table A, next page.) 



" In 1833 and 1837, the wines were scarcely 

 drinkable. A summer whose mean temperature is 

 below sixty-seven degrees will not produce valuable 

 wine." 



1 Blodgett's Climatology, p. 439. 



4 



