"The later meteorological statistics do not prove that the progressive opening of the country has had so powerful an influence upon the temperature of the atmosphere as is generally supposed. Its chief tendency seems to be to lengthen the summer, and thus abridge the duration of winter. That the gradual removal of the forests to make room for open fields contributes to augment the summer temperature, is undoubtedly true, since it is well known that the atmosphere itself is not heated by the direct rays of the sun, but that its warmth springs from the earth, and that the degree of this warmth is entirely governed by the quantum of heat absorbed through the earth's surface. The progressive settlement of the country may then be expected to benefit the climate, by its throwing open to the direct action of the sun a more extended surface of territory; and this benefit will be more sensibly felt at night, from the earth's having imbibed a sufficient quantity of caloric to temper the coolness of the air between the setting and rising of the sun. In an agricultural point of view, such an improvement in the climate of Canada will be of great moment, as the coldness of the nights is generally the cause of blight in tender fruits and plants; and from its equalizing the temperature, probably render the climate capable of maturing fruits that are indigenous to warm countries. "Notwithstanding the opposing testimony of meteorological data, we have the assertion of some of the oldest inhabitants of the country that the climate of Canada has become perceptibly milder within their recollection, and are thus left to conciliate this traditional record with contradictory facts, and the only mode of doing so appears to be the application of their remarks, more to the duration of the mild season than the degrees of cold that were indicated by the thermometer in the course of the year."--Bouchette, vol. i., p. 334, 340, 1831; Lambert's _Travels through Canada_ in 1808, vol. i., p. 119. Kalm says in 1748, September 12th, "The weather about this time was like the beginning of our August, Old Style. Therefore it seems that autumn commences a whole month later in Canada than in the midst of Sweden."--P. 682. [Footnote 223: On the theory of the isothermal lines, see the papers of Kupfer in Poggend., _Ann._, bd. xv., s., 184, and bd. xxxli., s. 270, in the _Voyage dans l'Oural_, p. 382-398, and in the _Edinb. Journal of Science_, new series, vol. iv., p. 355. See, also, Kamtz, _Lehrbuch der Meteor_, bd. ii., s. 217, and on the ascent of chthon-isothermal lines in mountainous countries, Bischoff, s. 174-197; Humboldt's _Cosmos_, vol. i., p. 347.]