158 NOTES ON MANITOBA. 



Having stated what the recorded facts as to rainfall are, I will 

 give my reasons for asserting that these facts are but the necessary 

 consequences of the physical conditions existing in the West of the 

 North American Continent. 



Tn the early part of this paper I referred to the position of the 

 Great American Desert and poinded out one of its effects on the air 

 curi-ents rising northward from the Gulf of Mexico — vLz„ its power 

 to attract and draw them to itself, and to the westward of their 

 natui-al coui'se. Another effect, now first mentioned, is that arising 

 from the heat given off froili the surface by radiation during the 

 summer months. The Gulf air currents, laden with moisture, when 

 drawn over the desert are met by the rarified and heated air ascend- 

 ing from its surface, and that rainfall which in the ordinary course 

 they would shower down (being prevented from falKng) passes on 

 and is wafted by the prevailing winds in the direction of our North- 

 West, where, being removed from the effects of the desert heat, they 

 give forth their long borne and priceless load in the form of our 

 summer rains. 



Having shown cause for the summer i-ains, I may, now, state that 

 the simple "suspension of those desert effects which gave the summer 

 rains" is the cause of the almost total absence of rain in the autumn 

 and winter periods. 



It was shown when writing on the winter temperature that as 

 the desei't cooled down the main air currents from the Gulf of 

 Mexico no longer pursued a westward course but passed to the east- 

 ward. This change of direction takes- them over the region of the 

 Canadian Lakes where they -deposit that rainfall which in summer 

 fell on the plains of the North- West. 



AGRICULTURAL OPERATIONS. 



The progress of the seasons and the labours of the husbandman 

 may be summarized as follows : 



Early in April the hot and unclouded sun clears^ from the lands the 

 last of its light snow-covering — thaws, and at the same time dries 

 the ground sufficiently to fit it for the plough^and almost simul- 

 taneously for seeding. Germination quickly follows and the young 

 roots, moistened by the thawing of the subsoil, follow the pores 

 opened out by the disintegi-ating power of the winter frosts, and 

 penetrate to a depth inconceivable to those who have not put the 



