companied by thaw and
rain: from the west, south, or north, the wind rarely blows. The most
sudden changes of weather consequent upon varying winds are observed
from the northwest, when the air becomes pure and cool; thunder storms
generally clear away with this wind: the heaviest falls of snow, and the
most continued rains, come with the eastern breezes.

The great lakes are never frozen in their centers, but a strong border
of thick ice extends for some distance from the shore: in severe
weather, a beautiful evaporation in various fantastic shapes ascends
from the vast surfaces of these inland seas, forming cloudy columns and
pyramids to a great height in the air: this is caused by the water being
of a higher temperature than the atmosphere above. The chain of shallow
lakes from Lake Simco toward the midland district are rarely frozen over
more than an inch in thickness till about Christmas, and are free from
ice again by the end of March. The earth in Upper Canada is seldom froze
more than twelve or eighteen inches deep, and the general covering of
the snow is about a foot and a half in thickness.

In Canada the Indian summer is perhaps the most delightful period of the
year. During most of November the weather is mild and serene; a soft,
dry haze pervades the air, thickening toward the horizon; in the
evenings the sun sets in a rich crimson flush, and the temperature is
mild and genial: the birds avail themselves of the Indian summer for
their migration. A phenomenon called the "tertian intervals" has excited
much interest, and is still unexplained: at the end of the third day
the greatest intensity of frost is always remittent, and succeeded by
several days of mild weather. The climate is so dry that metals rarely
are rusted by exposure to the air. This absence of humidity prevents the
extremes of heat and cold from being so powerful here in their effect
upon the sensations of the human frame as in other countries.

The Aurora Borealis, or northern lights,[162] appear with great
brilliancy in the clear Canadian sky, especially during the winter
nights. Starting from behind the distant horizon, they race up through
the vault of heaven, spreading over all space one moment, shrinking to a
quivering streak the next, shooting out again where least expected, then
vanishing into darkness deeper than before; now they seem like vast
floating banners of variegated flame, then as crescents, again as
majestic columns of ligh