No. XXIV. "Very distant posterity will one day decide whether, as Mr. Leslie has endeavored to prove by ingenious hypothesis (An Experimental Inquiry into the Nature and Propagation of Heat, 1804), 2400 years are sufficient to augment the mean temperature of the atmosphere a single degree. However slow this increment may be, we must admit that an hypothesis, according to which organic life seems gradually to augment on the globe, occupies more agreeably our imagination than the old system of the cooling of our planet and the accumulation of the polar ice."-Humboldt's Personal Narrative, vol. ii., p. 83. 66 A point of much interest is the comparison of the actual temperature of the globe with that of the same regions in former ages. The evidence which justifies the conclusion that no change has occurred but from local or superficial causes, is worth studying, were it only for its variety and singularity. We might begin with Laplace's conclusion, that the mean heat can not be altered by 1° of Réaumur since the time of Hipparchus, inasmuch as the dimensions of the globe would be thereby changed in a small amount, its angular velocity be increased or diminished, and a sensible difference be made in the length of the day, which difference does not exist. We might then proceed to the argument urged by Biot and Champollion, from the identity of the time of inundation in the Nile, 5000 years ago, the periodical rains producing which depend upon and indicate the degree and distribution of heat over a vast equatorial region. Next we might turn to the method of Professor Schaw, in his work on the comparative temperature of ancient and modern times, founded on the northern and southern limits of production of different animals and plants in any given country, as they come recorded to us by ancient writers, compared with the observations of our own day. The result of general identity is obtained by this method also; and the same remark may be extended to the miscellaneous proofs derived from other passages in ancient writers, numerously collated, respecting the climate of particular regions and localities. There is no amount of diversity shown by this evidence which does not admit of explanation from local and accidental causes, many of them belonging to the agency of man himself, on the surface of the earth. -Quarterly Review, September, 1848. "Several planters attribute the failure of the cotton crop this year (1842) to the unusual size and number of the icebergs, which floated southward last spring from Hudson's and Baffin's Bays, and may have cooled the sea and checked the early growth of the cotton plant, so numerous and remote are the disturbing causes of meteorology! Forty degrees of latitude intervene between the region where the ice-floes are generated and that where the crops are raised, whose death-warrant they are supposed to have carried with them."-Lyell's America, vol. i., p. 174. No. XXV. The theory by which Dr. Brewster seeks to account for the peculiarities of the American climate is the following: "He supposes that the poles of the globe and the isothermal poles are by no means coincident, and that, on the contrary, there exist two different points, within a few degrees of the poles, where the cold is greatest in both hemispheres. These points are believed by Dr. Brewster to be situated about the eightieth parallel of latitude, and in the meridians of 95° east and 100° west longitude. The meridians of these isothermal poles he considers as lying nearly at right angles to the parallels of what might be called the meteorological latitudes, which, according to his theory, appear to have an obliquity of direction as regards the equator something like the zodiac. Thus the cold circle of latitude that passes through Siberia would be the same that traverses the frigid atmosphere of Canada. This theory would go some length toward explaining the causes of the gradual decrease of the severity of cold in the south of Europe, and lead us to the conclusion that eventually the cold meridian of Canada may work its way westward, and leave that part of America to an enjoyment of the same temperature as those European countries situated in corresponding latitudes. That the temperature of the air has been modified by agricultural operations can not be denied, but that these operations should of themselves be capable of producing the changes known to have taken place in the course of ages in Europe, where formerly the Tiber used to be often frozen, and snow was by no means uncommon at Rome;† when the Euxine Sea, the Rhone, and the Rhine, were almost every year covered with ice, of sufficient thickness to bear considerable burdens, it is scarcely possible rationally to admit; and, indeed, the meteorological observations, as far as they go in Canada, serve rather to disprove than to establish the fact."-Bouchette, vol. i., p. 335. "The earliest record of the climate of Canada is that contained in the Fastes Chronologiques,' and refers to the period of Cartier's sec On the theory of the isothermal lines, see the papers of Kupfer in Poggend., Ann., bd. xv., s., 184, and bd. xxxii., 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. + Quebec lies nearly in the same latitude as Paris, and from the description which the Emperor Julian has given of the winters he quartered there during his command in Gaul, therc seems to be little difference between the winters of France in this respect and the present winters of Canada.—Juliani Imper., Opera. The author of Récherches Philosophiques sur les Américains supposes the difference in heat between the two continents to be equal to 12 degrees; that a place 30 degrees from the equator in the Old Continent is as warm as one situated 18 degrees from it in America, tom. i., p. 11. Dr. Mitchell, after observations carried on during thirty years, contends that the difference is equal to 14 or 15 degrees of latitude, p. 257.— Heriot's Travels through the Canadas, p. 117. ond voyage. On the 15th of November, 1535, Old Style, the vessels in the River St. Charles were surrounded by ice, and the Indians informed Cartier that the whole river was frozen over as far as Montreal. On the 22d of February, 1536, the River St. Lawrence became navigable for canoes opposite to Quebec, but the ice remained firm in the St. Croix harbor. On the 5th of April his vessels were disengaged from the ice. To obtain the modern dates, it will be necessary to add eleven days to each period. "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. No. XXVI. The Vitis vinifera is found in America in its wild state; in James's "Expedition to the Rocky Mountains" it is thus described: "The small elms along this valley were bending under the weight of innuVOL. IN merable grape vines, now loaded with ripe fruit, the purple clusters crowded in such profusion as almost to give a coloring to the landscape. On the opposite side of the river was a range of low sand-hills, fringed with vines, rising not more than a foot or eighteen inches from the surface. On examination, we found these hillocks had been produced exclusively by the agency of the grape vines, arresting the sand as it was borne along by the wind until such quantities had been accumulated as to bury every part of the plant except the end of the branches. Many of these were so loaded with fruit as to present nothing to the eye but a series of clusters, so closely arranged as to conceal every part of the stem. The fruit of these vines is incomparably finer than that of any other native or exotic which we have met with in the United States. The burying of the greater part of the trunk with its larger branches produces the effect of pruning, inasmuch as it prevents the unfolding of leaves and flowers on the parts below the surface, while the protruded ends of the branches enjoy an increased degree of light and heat from the reflection of the sand. It is owing, undoubtedly, to these causes that the grapes in question are far superior to the fruit of the same vine under ordinary circumstances. treatment here employed by nature to bring to perfection the fruit of the vine may be imitated, but, without the peculiarities of soil and exposure, can with difficulty be carried to the same magnificent extent. Here are hundreds of acres, covered with a movable surface of sand, and abounding in vines, which, left to the agency of the sun and of the winds, are, by their operation, placed in more favorable circumstances than it is in the power of man to so great an extent to afford."-Vol ii., p. 315, 316. The No. XXVII. "Fir-trees, Thuja, and Cypress-trees are a northern type, which is very rare in the tropical regions. The freshness of their evergreen leaves cheers the desert winter landscape; it proclaims to the inhabitants of these regions that although snow and ice cover the earth, the internal life of the plants, like the fire of Prometheus, is never extinguished."-Cosmos, vol. ii., p. 90. "There are upward of twenty species of Pinus, of which one half are natives of Canada, Nova Scotia, or Newfoundland. "Pinus Balsamea (Balm of Gilead Fir, or American Silver Fir) grows to the height of fifty feet, and is an elegant tree, resembling the silver fir of Europe. The resin of this species is the common Canada Balsam, which is often substituted for the Balm of Gilead. It is found in small blisters on the bark, extracted by incision, and received in a limpid state into a shell or cup. This tree has long been cultivated for curiosity in England, but in general, though it grows to a considerable size and height, scarcely survives above twenty years, which seems to be the natural period of its existence. Mr. Lambert men tions some older trees of this species at Woburn and Warwick Cas tle. "Pinus Canadensis (Hemlock Spruce) is a beautiful and very large tree, bearing some resemblance in its foliage to the common yew. Peter Collinson records his having introduced this tree to the English collections in 1736, and a fine specimen of it is, or was, in his garden at Mill Hill. "Pinus Nigra (Black or Double Spruce) is Nova Scotia, and terminates in latitude 65°. found from Canada to It was introduced into England about the year 1700, but not much cultivated there. "Pinus Alba (White Spruce) flourishes from latitude 43° northward. Its growth is nearly equal to that of the European silver fir, 140 feet in height. It is one of the most ornamental of the Abies tribe (those having single, not fasciculated leaves); the branches feather down to the ground, and the leaves have a beautiful and peculiar glaucous hue. From the young shoots of this tree (also from Pinus Nigra) is obtained the resinous extract from which spruce beer is made: good turpentine is obtained from the bark. This tree was cultivated in England by Bishop Compton before 1700. "Pinus Resinosa (Pitch Pine) grows in Canada in close forests, and is distinguished for its great height and smooth red bark, whence it is often called Red Pine by the French population. This tree is the glory of Canada. Its timber, in color, quality, and durability, appears to be in every respect equal to the best Riga, and in one particular superior, that of being quite free from knots. It was first raised in England by the Duke of Northumberland at Zion House, where many of this species are still to be seen flowering in May. "Pinus Banksiana (Labrador Scrub, or Gray Pine) inhabits cold, barren, and rocky situations. The finest trees of this species in England are at Pain's Hill and Kew. When “Pinus Strobus (White, or Weymouth Pine) is the largest species on the eastern side of the Rocky Mountains, being sometimes 200 feet high, and the trunk five feet in diameter. The attention which Lord Weymouth, afterward Marquis of Bath, gave to the cultivation of this valuable tree has justly stamped it with his name. It is now generally diffused through every considerable plantation in England. growing in open situations, it is feathered to the ground; but, as gen erally found in the Canadian forests, it is little more than an immense stick with a quantity of brush at its head, in about the same proportion as the hair on the tail of an elephant. It is of this tree that in general the forests of all British America are composed, and it is, in fact, peculiar to America. It is called in commerce White Pine, Yellow Pine, or American Pine. The timber is very valuable for masts. The age to which this tree arrives is not known: 1500 annular divisions have been counted. Pinus Pendula (Black Larch, or Hackmatack) is a beautiful and large tree, generally resembling the larch of Europe. The buds are black, and yield a fine turpentine. This tree was first raised in England by the celebrated Peter Collinson, whose original tree, one of the 66 |