THE FARM AND METEOROLOGY. 439 



It will be seen, therefore, that in cooler countries, like Scotland, a larger 

 amount of heat is required to mature the crop than in countries where the 

 is more powerful. In Egypt, on the banks of the Nile, with a mean 

 temperature of 70 F., barley requires only 90 days ; and in South Amer- 

 ica corn comes to maturity in 92 days, with a mean temperature of 81*5 

 Kxampl'-s might be multiplied, but it is unnecessary to do so, since 

 those already given will sufficiently show that the productive power of the 

 h may be doubled by the quickening energy of powerful heat, for two 

 crops in one season become a possibility. 



Although in a less degree, many important differences in the kind, quan- 

 tity, and quality of our own farm produce spring from the same cause, 

 Altitude is often equivalent to latitude in its effect upon climate. If 

 F. may be taken as the mean temperature of a good vegetating season in 

 Britain, say from 1st April to 30th September, an elevation of 590 feet 

 will be equivalent to the loss of 1 on an average. Such situations are 

 i to a greater range of temperature than lower and more sheltered 

 places, owing to unchecked radiation during the night, and the conse- 

 i element of uncertainty, which from time to time involves the 

 of a crop. The following facts relating to the effect of climate upon 

 pm<lu<v may serve to illustrate this point further : 



English-grown wheat is inferior in quality to that from the south-east, 

 K u rope, and hot countries in general such as the American continent. 

 1 1 has been found that Indian sorts of wheat are relatively cheaper, com- 

 pared with other qualities, and accordingly they have grown in demand. 



