FIFTEENTH ORDINARY MEETING. 197 
peach grows luxuriantly far northward along the eastern side of 
Lake Michigan, and over several thousand square miles in the Pro- 
vince of Ontario. The area over which the peach can be grown in 
this Province is nearly ten thousand square miles. It is even found 
to succeed on favorable soils and situations at Owen Sound, on the 
Georgian Bay. 
If the winter cold of the Province of Ontario is mitigated by the 
Great Lakes, so also is the summer heat. The great central plains 
of the Mississippi and Missouri in summer become so heated that the 
mean temperature of July in Missouri and Kansas is little less than 
that of New Orleans in the same month. The influence of the solar 
rays on these great interior plains is so great that the trade winds of 
the Atlantic, drawn eastward into the Gulf of Mexico, are deflected 
northward and, affected by the prevailing eastward drift of the at- 
mosphere, are finally carried, charged with moisture, north-eastward 
occasionally to the Ohio valley and the borders of the Great Lake 
region. Far northward, in summer, torrid influences prevail. Tem- 
peratures of 110° and upward are experienced in Dakota and Mon- 
tana, and even further north across the international boundary of 
49° in the Canadian valleys of the tributaries of the Missouri. But 
the Great Lakes interpose a buffer against the easterly drift of the 
interior heat. The isothermals which in winter trend southward 
after leaving the lake region, in summer trend north-westerly beyond 
Lake Michigan. The July isothermal of 74°, which is found in On- 
tario only in the very warmest localities of the Province, reaches a 
parallel two hundred miles further north in the great plains of the 
west. The mean temperature of 70° for the three midsummer 
months, which in Ontario is found rarely northward of the 43rd 
parallel, is reached very nearly as far north as the 49th parallel 
in the North-Western States and Territories. It is not until 
October that latitude for latitude and altitude for altitude the mean 
temperatures of Ontario and the Mississippi valley are equalized. 
The decline in temperature thenceforward till winter has set in is 
more rapid in the Mississippi valley than in the region of the Great 
Lakes which, warmed by the summer’s heat, delay the advent of 
winter several weeks after that season is established in the central 
parts of the continent. The advent of spring in the lake region is 
also later than in the west, partly owing to the retarding effects of 
the lake water, which has been chilled by the winter’s cold, 
