44 BOARD OF AGRICULTURE. [Pub. Doc. 



least rapid over water areas ; also that in the same latitude 

 it is colder on the eastern side of the continents and warmer 

 on the western, due to the air and ocean currents. The 

 most equable temperatures are found near large water areas, 

 and the places of greatest absolute ranges in temperature 

 are in the centre of large land areas. It is found also that, 

 while the region of greatest cold in the northern hemisphere 

 is around the pole during the summer months, it is not there 

 in the winter, but there is a marked cold pole in northern 

 Siberia, where the mean temperature for January is — 60". 



In determining the climate of a place in reference to its 

 moisture, the most important data are the mean monthly and 

 annual fall of precipitation and the mean frequency of rain- 

 fall in each month. A district may have a large annual fall 

 of rain, yet be worthless from an agricultural stand-point, 

 l)ecause the rain comes in a few heavy storms, or there may 

 be wide intervals without rain when droughts prevail. Even 

 when rain comes with a fair regularity of fall, if the average 

 annual amount be under eighteen inches, agriculture can sel- 

 dom be safely practised without irrigation, and grazing be- 

 comes the leading occupation. When the average fall is 

 less than twelve inches, the region is practically reduced to 

 a desert, and generally the water supplies are too small to 

 be of benefit in irrigation. 



But, on the other hand, if the rainfall of a district be over 

 one hundred inches, the vegetable growth is generally so 

 luxuriant that the land is occupied and worked with diffi- 

 culty. The rainfall over most of the temperate zone of the 

 northern hemisphere is from forty to eighty inches, the 

 amount being greatest in southern sections and decreasing 

 with a fair degree of uniformity toward the north. It is 

 interesting to note that, in regions where the temperature is 

 best fitted for human existence and for the best development 

 of all the human faculties, the amount of rainfall is also that 

 under which human occupations are best developed. 



The wind values that go to make up the climate of a place 

 are the mean velocity and prevailing direction for each 

 month and the year, whether the high winds are moist or 

 drj-^, and whether the prevailing winds are continental or 

 oceanic ; if continental, whether they come as warming and 



