LAND AND OTHER AGENTS OF PRODUCTION 133 



recovered, to go once more through the whole process of cutting, burning, 

 and planting. 



Evidently, then, vast areas within the tropics are beyond the pale of 

 agriculture, or else can be cultivated only in a most haphazard way. The 

 kind of intermittent agriculture which alone is possible in many jungle- 

 covered parts of tropical lands is most demoralizing. Inasmuch as the 

 people must change their fields every year and may in some years be unable 

 to burn the brush which they have cut, they have no feeling of permanence. 

 In many cases there is no definite ownership of land, and even where this 

 exists the owner has nothing to encourage him to improve his holdings. 

 It is useless or, in fact, sheer waste of time to attempt to improve a tract 

 which next year is to be abandoned once more to the jungle. 



36. LOCAL AND SEASONAL PECULIARITIES OF CLIMATE 



O) FROSTS 1 



BY HARRY J. WILDER 



The controlling factor in grape production is not one of mean 

 seasonal temperature, but rather of seasonable and unseasonable 

 frosts. To illustrate (in the region of northeastern Pennsylvania, 

 adjacent to Lake Erie), an equalized temperature curve extends from 

 the lake shore belt southward to include almost all of Crawford and 

 Mercer counties, but the length of the frost-free season is much 

 greater along the lake shore than well up on the escarpment. The 

 tempering influence of the lake on the climate of the adjoining plain 

 is well known. A further fact has been demonstrated in that a part 

 of this modifying influence extends for at least a little way up the 

 escarpment slope to the south, thus making possible an extension of 

 the vineyard interests. But it is only for a short distance south of 

 the escarpment that the frosts are held off long enough in the early 

 autumn to make grape growing safe. 



In the southern district, too, the advisability of setting tree fruit, 

 particularly apples, depends in some measure upon the relative 

 immunity from late spring frosts, while the corn crop and vegetables 

 as well are similarly affected. These climatic problems are primarily 

 local rather than regional in scope, as is illustrated by the frequent 

 loss, in hollows or depressions, of fruit and other crops by late spring 

 frosts. 



1 Adapted from loth Report of the Field Operations of the Bureau of Soils, 

 pp. 220-23 and 1169-73. 



