131. THE remaining points proposed for communication are in South America. 5. The river Atrato, which empties into the Gulf of Darien, approaches in two points by its branches to the Pacific. 6. The Naipa, which enters near its mouth, is navigable to a point within five or six leagues of the port and bay of Cupica, which should be the Suez of the new continent. The interval is quite level, and well adapted for a canal. 7. Near the source of the Atrato a small branch, called the River Quito, is connected by the small ravine of Raspadura with the head waters of the St. Juan, which empties into the Pacific. By the energy of a single priest and his parishioners, a small canal was dug in 1788 along the ravine, by which canoes laden with produce pass from sea to sea during the time of heavy rains.

It is obvious that no point yet examined presents so few difficulties in the way of this great object; and the government of Columbia have directed the necessary surveys to be made in reference to it. Of the two remaining routes, that which was suggested from the Gulf of St. George to the ocean is quite impracticable: the other presents a communication comparatively easy, by a portage over the mountains of only five or six leagues from the river on the Peruvian coast, 10° south latitude to the branches of the Amazon, and would carry the rich produce of Peru and Chili to the mouth of the Amazon and the coast of Europe in five or six weeks; while a passage of four months, attended with great danger, is necessary in going round Cape Horn. The jealousy of the Brazilian government at present renders the plan impracticable. The only canal yet executed in this district of North America is the great drain, or derague of Huehuetoca, designed to draw off the waters by which the valley and city of Mexico are frequently inundated. Although it serves no commercial purpose, it claims admiration as one of the most gigantic hydraulic constructions in the world. It was originally a subterraneous passage through the crest of mountains which surrounds the valley of Mexico; but, being found inadequate, it was converted at an immense expense into an open drain, more han twelve miles in length and nearly 200 feet in depth in some parts, and 200 or 350 feet broad; in some parts nearly equal to the Seine at Paris. If but a small part of it were filled with water, snips of war might pass through the mountains. It is now much fallen to decay.

the

132. CLIMATE.-It is a well-known fact, that temperature of countries on the eastern coast VOL. II.-PART 1.

of North America, beyond the limits of the tropical heats, corresponds to that of countries seven or even ten degrees farther north in Europe. Various causes have been assigned for this difference, none of which have appeared satisfactory. The prevalence of north-west winds, the extensive forests, the great lakes, the extent of land on the north in America, have all been alleged as the causes of this supposed anomaly in climate.

133. But all these theories proceed on the ground that the temperature of Europe is that which is naturally produced by its latitude. The fact really is, that scarcely any other portion of the globe, of the same extent, is so much subject to the influence of local causes: it is sheltered from the bleak winds from the north by the Scandinavian chain of mountains: it is surrounded on the north by the ocean immediately communicating with the Atlantic, and intersected by extensive seas whose waters preserve an equable temperature, and give it out to moderate the severity of winter. Its southern countries are still more sheltered by ranges of mountains passing from east to west; and are bordered by a sea extending into a hot climate, and transporting its heats by currents and winds with great rapidity. The deserts of Africa on the south are like immense furnaces, raising the temperature of all the surrounding countries. America on the other hand is exposed to the common influences of the season without shelter, and would therefore be more likely to furnish a fair standard of the temperature of the earth. But we shall find, on further examination, that the eastern coasts of both continents, so far as they have been examined, appear to resemble each other, and to have colder climates than the western. The eastern coast of Asia resembles that of North America in the greater severity of its climate. On the other hand, the western coast of America, so far as it has been explored, has been found to have a climate milder than the eastern. The most important circumstance, probably, which is concerned in producing the more elevated temperature of Europe, is the prevalence of south-west winds upon its western coast. How far this is the case on the western

coast of America we are not informed; but it is well known that the south-west wind, coming of course from a warm climate, blows about two-thirds of the year upon the western coast of Europe, and therefore continually modifies its climate by mingling the warm air of the tropics in its atmosphere. In correspondenc

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with this view we shall find that the cold increases in going into the interior of Europe. The growth of plants in Russia, where we have no accounts of temperature, indicates a temperature still lower in that country; and the strongest evidence is furnished that, in moving inland, we are leaving some important source of heat. That it is not merely the ocean which causes the difference, is evident from the fact that no such change occurs on the eastern coast of America; and we are left without any other means of accounting for it than the prevalence of the wind we have mentioned. It is a singular fact, also, that the lines described by Mr. Young as bounding the various climates of France, instead of following the parallels of latitude, pursue a course perpendicular to the direction of this wind, as if

this were the governing cause, rather than distance from the diurnal path of the sun.

134. If we add to this, that the prevalent winds on the coast of America are from the north-east and north-west, we shall have good grounds for anticipating a great difference of temperature from these sources alone. The combination of causes we have mentioned justifies the opinion, that America is probably a better standard for the general temperature of the earth than Europe, and all the accounts we have of Asia confirm this opinion.

135. The following table, presenting a comparative view of the mean temperature of places in the same latitude, but in different situations, affords an illustration of the remarks which we have made.

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the continent as it is divided by the gradations of temperature, or isothermal lines, into various regions, distinguished by the same prominent characteristics of climate, and furnishing similar productions. For this purpose we shall describe particularly the course of the principal isothermal lines; and, in order to furnish the best opportunity for comparison, we shall trace them in their progress over the eastern continent, relying chiefly on the original and interesting papers on this subject, which have been published by Baron Humboldt. It has been said that the climate of America is growing milder, as the forests are destroyed; but it is by no means proved. On the contrary, the mean temperature does not appear to have varied. At the same time it is true that the winters have become shorter and more open, while the spring and summer are proportionably colder, and the seasons are less uniform. Changes of the same nature, however, take place in Europe; and in Europe, as well as in America, a series of mild seasons contrasted with some preceding seasons of uncommon severity, has been made the ground of a false conclusion as to the amelioration of the climate.

137. The coldest, or frozen region of North America, may be considered as extending from the northern limits of the isothermal line of forty-one degrees, which corresponds nearly to the utmost northern limit of the oak and wheat. The last oaks are seen on the coast of Norway, in latitude sixty-three degrees; on the gulf of Bothnia, above sixty degrees; in Russia, at fifty-five degrees; and in Siberia, stil lower. In North America this line is found at the bay of St. George in Newfoundland, in latitude forty-nine, and generally at fifty degrees on the eastern coast; but it rises higher on the western. In the coldest parts of this region brandy and mercury freeze during the winter; and masses of snow and ice continue through the summer, covering a large part of the country. Wells are frozen at a great depth; and at Hudson's Bay, and in most parts of this region, no water can be obtained in winter, except by melting snow and ice. At the depth of three feet the ground is frozen in summer at Hudson's Bay; and lakes and standing waters of no great depth are frozen to the bottom in the winter. The inland waters continue frozen from seven to nine months; and snow, which begins to fall in August, continues from eight to ten months in

all parts.

138. During the winter, the inhabitants of the coldest parts remain crowded together in small buts. The whole inside of a hut or ship is usually lined with ice, formed from the vapour of the breath, which must be cut away every morning. The savages even build huts of snow, stop the openings with ice, and use it as glass. Every part of the body must be covered in going out, or it is instantly frozen. The air, when breathed, seems to pierce and even rend Belongs. The cup often freezes to the lips, if it is touched in drinking. The provisions must be cut with hatchets and saws. Trees and the beams of houses are split by the frost, and rocks

139. The change from winter to summer is very sudden, and the valleys are covered with grass a few days after the snow has melted. The temperature of the summer is very uniform; and the heat of the sun is often oppressive from the length of the days. In most parts of this region the summer is too short to bring grain to maturity. Cultivation is practised only to a very limited extent, and without any certainty of a crop, although this part of North America is in the same latitude with Denmark and Great Britain.

140. At Melville Island, the extreme point of Captain Parry's voyage, he states the mean annual temperature to be only one degree and a half, while at the North Cape of Europe, nearly in the same latitude, it is thirty-two degrees.

141. The isothermal line of 50°. corresponding nearly to the limit of the wine-grape in the middle of Europe, there passes along the parallel of 50°.; on the western coast it ascends to 52°. ; and in England, to 54°.; but in going eastward from Germany, it continually descends; and we find it as low as 45°. in Asia. But in North America, it commences on the coast at Boston, in latitude 42°. On reaching the basin of the Mississippi, beyond the Hudson River, it ascends to the borders of the great lakes: it descends again beyond the Mississippi; but again rises beyond the Chippewan Mountains; and is supposed by Humboldt to strike the western coast in latitude 50°. The region north of this line, extending to the utmost limits of the oak, may be termed the Cold Region, embracing the British provinces and the northern part of New England. In this region the winters commence in November and end in April. The change of seasons is sudden; frosts begin in September, and often continue through the month of May. The air is keen and penetrating, but clear and salubrious; and the climate appears remarkably favourable to long life. The cold is remarkably steady; and it is said that it is more easily endured, than that of milder climates, which are subject to frequent changes. The snow is permanent; and the sled-roads afford a rapid and easy mode of transportation through the winter. In Nova Scotia and Canada the rivers freeze to the thickness of several feet, and snow lies through the winter; while in France, in the same latitude, snow is rare, and the rivers are seldom frozen at all.

142. Little vegetation appears in the interio before April, and then springs up immediately after the snows are melted. The summers are short, but hot, and sometimes oppressive. They are as warm at Quebec as in the middle of France. The climate is adapted to the coarser grains; but wheat flourishes chiefly in the southern parts. The pastures are rich, and the verdure fine. Apples, pears, cherries and plums are easily cultivated, of the finest quality, and in the greatest abundance. All the species of berries are abundant, and some very delicious, as strawberries, gooseberries, &c. The