12 BOTANY OF L,A SAL,LE COUNTY. 



often escape frosts which devastate the prairies from 

 being- sheltered by excessive fogs, which in the autumn 

 are very frequent and not altogether unknown in the 

 spring. 



The winds of summer are largely from the south- 

 west or some point near it, with some from the south- 

 east and an occasional breeze from the northwest and 

 northeast. The southwest winds are often dry and 

 warm and very unpleasant, but during the winter they 

 are our most chilly winds, at least for the first day 

 or half day of their continuance. Northeast winds are 

 very common in April and May and are generally damp 

 and chilly. Northwest winds are common but not 

 pervailing winds through the winter and while cold are 

 often as dry and take up moisture with as much avidity 

 as the southwester of summer. 



We have then a very changeable climate with ex- 

 tremes of heat and cold and during most of the year 

 rapid evaporation, the dry atmosphere sucking up 

 moisture with great rapidity, drying up the ground 

 and checking the growth of vegetation and sometimes 

 rendering abortive all the farmers' eiforts to secure a 

 crop. Such a climate seems to require some more reg- 

 ular supply of water than our rains furnish and we 

 believe irrigation would be found profitable and once 

 introduced would come rapidly into favor. 



We have made no comparison of the mean annual 

 temperature of Ottawa and other places because such 

 a comparison' is to the last degree misleading and de- 

 lusive, Let one reflect for a moment on what mean 

 annual temperature means. Suppose we have two 

 places of which the mean annual temperature is 50 deg. 

 What does this tell us about their climate? Nothing 

 whatever! These figures would seem to indicate that 

 they had the same or similar climates. But if we take 



