438 THE HOME, FARM AND BUSINESS CYCLOPAEDIA. 



heat. Shelter, or protection from exposure, is highly valued, although in 

 sultry weather we may long for the breezy unsheltered down or mountain 

 side. Shelter is among the few climatic conditions which may be con- 

 trolled, and hence a great deal of attention is given to it by agriculturists. 

 A sheltered situation for house or homestead may be chosen, or trees may 

 be planted, which in time will give what nature has denied. 



There is also a larger sense in which the term shelter is applied, as when 

 a range of mountains give shelter to a large district or fertile valley, con- 

 ferring upon thousands of acres the advantages of an improved climate. 

 A good example of this is seen in the grazings under the shelter of the 

 Rocky Mountains. 



CHARACTER OF THE SOIL is one more factor in the sum total of condi- 

 tions which control climate. Any one may notice that the fog on an au- 

 tumn evening hangs over a clay bed just as it hangs over a rock in mid- 

 ocean. The cold nature of the clay ground first condenses the atmospheric 

 vapour into a visible form. Delicate animals such as turkeys cannot be 

 reared upon clay land, and clay land districts are injurious to persons 

 afflicted with weak lungs. On the other hand, a dry soil admitting of free 

 drainage gives a warmer and dryer, and, in a word, a more wholesome at- 

 mosphere. 



It is by modifying the character of land that drainage is considered to 

 be a positive improver of climate. Artificial drainage causes water to 

 quickly disappear beyond the influence of evaporation, ad gives those ad- 

 vantages to a clay soil which are originally enjoyed only by those that are 

 naturally drained. 



INFLUENCE OF CLIMATE UPON THE PRODUCTIVE POWERS OF THE SOIL. 

 The importance of climate upon the fertility of soils can scarcely be over- 

 rated. It is seen not only in the different amount and character of the 

 products of tropical and temperate countries, but also in the varying yield 

 of our fields from year to year. A few facts bearing upon these points 

 may perhaps be here introduced with advantage. 



It is an ascertained fact that the period required to mature any crop 

 varies with the climate. Wheat requires 1GO days to ripen near Paris, 

 182 days in Scotland, and only 85 days at Guelph, in Canada. So com- 

 pletely does the period of growth and maturation depend upon the total 

 amount of heat a crop receives, that the mean temperature of a wheat- 

 growing country (taken during the period of growth) multiplied by the 

 number of days required to perfect the crop, gives approximately the same 

 numerical result. In other words, the total amount of heat required to 

 perfect a crop of wheat is approximately the same. 



