Sid 
174. Major Lachlan on the Rise and Fall of the Lakes. 
“‘ As the temperature of the climate in America depends chiefly 
on the winds, the formation of that continent is evidently the 
cause of the frosts being more intense than in countries in paral- 
lel latitudes in Europe; a consequence arising principally from 
the much greater breadth of America towards the poles. inds 
change their character in America. Northeast winds, which are 
cold and dry in Europe, are wet and truly disagreeable in America. 
Northwest winds are, on the contrary, cold and dry, and are fre- 
quent during winter in America, much about the same period 
that northeasterly winds prevail in Europe. One great, if not 
the principal, cause of cold in America, is the direction of the 
mountainous ranges and basins of country which conduct or in- 
fluence the course of the winds. While the sun is to the south 
of the equator, the winds less under solar influence prevail from 
the northwest, following, however, the great features of the con- 
tinent. The winds blowing over the vast regions of the north 
are always piercing and intensely cold. The return of the sun, 
again, by the diffusion of heat, agitates the atmosphere and alters 
e winds, which blow from a contrary direction, till the equl- 
librium is produced. This, however, does not appear to require 
much time, as no wind blows scarcely forty hours together from 
any one point. \ 
‘The comparative depths of the Lakes forms another extraordi- 
nary subject of enquiry. ‘The bottom of Lake Ontario, which 
is 452 feet deep, is as low as most parts of the Gulf of St. Law- 
rence, while Lake Erie is only 60 or 70 feet deep; but the bot- 
oms of Lakes Huron,* Michigan and Superior, are all, from their 
vast depth, although their surface is so much higher, on a level 
with the bottom of Lake Ontario. This is certainly not impos- 
sible ; nor does the discharge through the Detroit river—allowing 
for the full probable portion carried off by evaporation—appeat 
by any means equal to the quantity of water which the three up- 
per great Lakes may be considered to receive. All the Lakesare 
estimated to cover 43,040,000 acres. The great Lakes occasion- 
ally rise above their usual level from three to five feet. These 
overflowings are not annual nor regular. They have occurred 
about once in seven years, and are probably the effect of more 
rain and less evaporation during the seasons in which they take 
place. Sir George Mackenzie observed occasional overflowings 
of two to three feet in the Lakes northwest of Lake Superior ; 
so that they are not peculiar to the Lakes of the St. Lawrence.” 
Having at length nearly exhausted my miscellaneous quota- 
tions and notes, [ propose concluding that main branch of my 
task with the following appropriate remark, derived from a note 
et. i - { Lakes, it is 
oper to note here tha that of Lake Haron has, ater al, been lately ascertained 
y the American Coast Survey to be not more than 420 instead of 860 feet !—s.% 
