egions of the earth. The greatest natural heat ever observed, which is 35 degrees of Reaumer, or 111 degrees Fahrenheit, has been at Bagdad, at 33° of latitude. The zone of the tropic of Capricorn contains but little land; but it appears to experience momentary heats of extreme intensity.

Most of the ancients, disregarding the observations of Polybius, conceived that the heat continued to increase from the tropic towards the equator. Hence they concluded that the middle of the zone was uninhabitable. It is now ascertained that many circumstances combine to establish even there a temperature that is supportable. The clouds; the greatrains; the nights naturally very cool, their duration being equal to that of the days; a strong evaporation; the vast expanse of the sea; the proximity of very high mountains, covered with perpetual snow; the trade winds, and the periodical inundations, equally contribute to diminish the heat. This is the reason why, in the torrid zones, we meet with all kinds of climates. The plains are burnt up by the heat of the sun. All the eastern coasts of the great continents, fanned by the trade winds, enjoy a mild temperature. The elevated districts are even cold; the valley of Quito is always green; and perhaps the interior of Africa contains more than one region which nature has gifted with the same privilege. Nothing equals the majestic beauty of the summer in the torrid zone. The sun rises vertically; it traverses in an instant the burning clouds of the east, and fills the heavens with a light whose effulgent splendour is unobscured by a single shade. The moon shines here with a more brilliant lustre, Venus blazes with purer and more vivid rays, and the milky way glitters with augmented brightness. To this magnificence of the heavens, we must add, the serenity of the air, the smoothness of the waves, the luxuriance of vegetation, the gigantic forms of plants and animals, all nature more grand, more animated, and yet less inconstant and less changeable.

9. Those parts of the earth contained between the tropics and polar circles, are called the two temperate zones: each of which is, therefore, 43° 4′ broad.

The north temperate zone extends from the tropic of Cancer to the arctic circle; and the south temperate zone from the tropic of Capricorn to the antarctic circle.

The temperate zones enjoy the mild and varied charms of

spring and autumn, the moderate heat of suminer, and the salutary rigours of winter. This succession of four seasons is not known beyond the tropics, nor towards the poles. Even that part of the north temperate zone which lies between the tropic of Cancer and the 35th degree of latitude, in many places resembles the torrid zone. Until we come towards the 40th degree, the frost in the plains is neither intense nor of long duration; and it is equally unusual to see snow fall there. Elevated countries feel all the rigours of winter-and the trees even in the plains lose their foliage, and remain stripped of verdure during the months of November and December.

It is from the 40th to the 60th degree, that the succession of the four seasons is most regular and most perceptible, without, however, endangering the health of man: MalteBrun observes, though, perhaps, not properly, that it is within these latitudes we must look for the nations that are most distinguished for knowledge and civilization, and those who display the greatest courage by sea and land. It would appear, that in countries where there is no summer, the inhabitants are destitute of genius, or, at least, of intelligence and taste; while in those regions where there is no winter, true valour, constancy, and loyalty, as well as other civil and military virtues, are almost unknown. But, let us remember that it is man himself, who has in a great measure created these salubrious climates: France, Germany, and England, not more than twenty ages ago, resembled Canada and Chinese Tartary, countries situated, as well as those portions of the earth, at a mean distance between the equator and the pole. Even the physical climate of that portion of the United States, situated about the 41st degree of north latitude, has, in less than half a century, undergone a very great change. for instance, in the city of New-York, for several years past, we have experienced mild winters, having had very little frost, and no long continuance of snow. This is principally owing to the clearing of forests; the cultivation of the soil; and the rapid improvement in the surrounding country; so that, in all probability, our climate may be in a few ages, as mild as that which is now experienced by those countries, situated in the same latitude in Europe.

11. Those parts of the earth included within the polar circles, are called the two frigid zones. The north frigid zone extends from the north pole to

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the arctic circle, and the south frigid zone from the south pole to the antarctic circle.

Beyond the 60th degree, and as far as the 78th, (which, as M. Malte-Brun remarks, appears to be the limit of the habitable earth in the northern hemisphere,) only two seasons are generally known; a long and rigorous winter, succeeded often suddenly by insupportable heats. The power of the solar beams, though feeble, from the obliquity of their direction, accumulates during the days, which are extremely long, and produces effects which might be expected only in the torrid zone. There have been examples, of forests having been set on fire, and of the pitch melting on the sides of ships. In winter, on the contrary, brandy has been frozen in heated rooms; the earth has been found frozen to the depth of 100 feet; and mercury, congealed in the thermometer, leaves the degree of cold indeterminate. We speak here of extreme cases and of the zone in general. For, in some places, a southern exposure, and the neighbourhood of the ocean, soften the climate to an almost incredible degree. Bergen in Norway, and the whole of the adjoining coast, between 60 and 62 degrees of latitude, has a very rainy winter, but seldom snow or frost-that season of the year is there less rigorous, and requires less fuel than at Craconia, or Prague, or Vienna, in Austria, between the 48th and 50th degrees of latitude. The frigid zone enjoys an atmospheric calm, which is unknown in temperate regions-it has no storm, no hail; scarcely a tempest-the splendours of the aurora borealis, reflected from the snow, dispel the darkness of the polar night. The heat of the sun from his long continuance above the horizon, astonishingly accelerates the growth of vegetation. In three days, or rather three times twenty-four hours, the snow is melted and the flowers begin to blow. The succession of physical zones is not equal in the two hemispheres: for, in the arctic seas, we scarcely meet with the large floating masses of ice before we arrive at the 70th degree, nor the stationary fields, until towards the 75th or 80th degrees of latitude; while, in the antarctic seas, both occur at from 50 to 60 degrees southern latitude. In the island of Terra del Fuego,.. in that of Sandwich, and in several others situated towards the 54th and 59th degrees of south latitude, the mountains even in the southern summer remain covered with snow quite to the shores of the sea.

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This diminution of heat appears to cease all at once be tween the 30th and 40th degrees of latitude; for hot winds arise from the interior of New Holland, whilst the mountains of Van Dieman's Land remain covered with perpetual snow; thus there is felt in these latitudes the most sudden transition from a suffocating heat to a very sensible cold. See, for farther information, respecting the causes of this phenomenon, M. Malte-Brun's System of Geography.

12. Climate, in a geographical sense, is a part of the surface of the earth contained between two small circles parallel to the equator; and of such a breadth, as that the longest day in the parallel nearer the pole, exceeds the longest day in that next the equator, by half an hour, in the torrid and temperate zones; or by one month in the frigid zones.

13. Physical climate comprehends the degree of heat and cold, the drought, the humidity, and the salubrity, which occur in any given region of the earth. The causes of physical climate are nine in number:

1st, The action of the sun upon the atmosphere. 2d, The interior temperature of the globe. 3d, The elevation of the earth above the level of the ocean. 4th, The general inclination of the surface, and its local exposure. 5th, The position of its mountains relatively to the cardinal points. 6th, The neighbourhood of great seas, and their relative situation. 7th, The geological nature of the soil. Sth, The degree of cultivation and population at which a country has arrived. 9th, The prevalent winds. M. Malte-Brun, Book XVII.

QUESTIONS.

What is the true latitude of a place on the ter-. restrial globe ?

What is the reduced latitude of a place on the surface of the earth?

What is the longitude of a place, and how is it

reckoned?

What is the greatest longitude a place can have? What is the declination of a heavenly body, and

how is it reckoned?

What is a zone, and into how many zones is the earth divided ?

What is the situation, and what is the extent of the torrid zone?

Where are the two temperate zones situated, and what is the extent of each?

Where are the two frigid zones situated, and

what is the extent of each?

What is a climate in a geographical sense, and what is a physical climate?

CHAPTER. VII.

Of the Natural and Artificial Divisions of Time.

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1. Time relatively to us, is the impression which a series of objects leaves upon the memory, and of which we are certain the existence has been successive.

Absolute, true, and mathematical time, of itself, and from its own nature, flows equally without regard to any thing external, and by another name is called duration: relative, apparent, and common time, is some sensible and external (whether accurate or unequable) measure of duration by. the means of motion, which is commonly used instead of true time; such as an hour, a day, a month, a year.

2. Mankind have universally agreed to make use of the diurnal and annual motions of the sun, for the purpose of measuring time.

It is proper to observe, that whenever the motion of the sun is spoken of, it is not to be understood in a positive sense, as if he actually removed from one part of space to another, but only as an appearance occasioned by the real motion of the earth in a contrary direction. The phenomena are exactly the same; and astronomers sometimes mention one, and sometimes the other, according as they find it most convenient for their purpose.