Undoubtedly, in the infancy of astronomy, when the ecliptic was first divided, and the divisions, or signs, were named, the several constellations lay in those they denominate. But now, owing to the precession of the equinoxes, the constellation Pisces is in the sign Aries, the constellation Aries is in the sign Taurus, and the tropics of Cancer and Capricorn, according to the sun's place among the stars, have become the tropics of Gemini and Sagittarius.

In its annual revolution, the earth describes an ellipse of slight eccentricity. Still the form of the orbit so far deviates from the circle, that we are nearer the sun by about three millions of miles towards the close of December, than at the opposite season, the end of June; and a corresponding variation is perceptible in the apparent diameter of the solar globe. It takes the uninformed by surprise to learn, that during the height of our summer, the earth is in that part of its path which is most distant from the sun, while during the severity of our winter it approaches the nearest to it. But the difference of the earth's distance from the sun in summer and winter is but inconsiderable, when compared with its total distance; and whatever change of temperature might arise from it under other conditions, is completely overpowered by the causes which produce the variations of the seasons. In winter, the solar rays reach us most obliquely, as the sun then rises to its least altitude above the horizon; and in proportion to the obliquity of the direction is a less number received on any given surface. It is also the case, that both light and heat are absorbed in passing through the atmosphere; and a ray will obviously have to traverse a larger extent of the atmosphere, according as the direction deviates from the perpen

dicular. Hence, as the sun of morning and evening is at all times less influential than that of the mid-day, so is the sun of winter less potent than that of summer. But the principal cause which overpowers the effect of variation of distance is, that in winter, when the earth is nearest the sun, the days in which heat is received are much shorter than the nights, when heat is lost. On the other hand, in summer, the effect of the increased distance of the sun is much more than counterbalanced by the increased length of the days and shortness of the nights.

The motions of our globe which have now been noticed, the diurnal rotation and annual revolution, with the direction and unvarying position of its axis, originate that pleasing variety of seasons which we experience, spring, summer, autumn, and winter, with their changes of temperature, different products, and diversified natural scenery. No physical law requires the rotation of the earth to be conducted as it is, either with reference to the velocity of the movement, or the direction of the axis. But while, as before remarked, the rate is adjusted to the welfare of organized creatures, so is the position of the axis of rotation. If one of the poles had been pointed to the sun (fig. 1), we should then have had one half the earth constantly in the light, and the other half in perpetual darkness, notwithstanding the motion of rotation and revolution. Or if the earth had its equator always in that position (fig. 2), then, by the daily rota

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tion, all places would be alternately in light and dark

ness for equal portions of time throughout the year: and though there would be different seasons in different parts of the earth, there would be no change of seasons at every place, as at present. But both these consequences are avoided by the axis of the earth being inclined 233° from a line perpendicular to its orbit, which is constantly retained during its annual circuit. By means of this simple arrangement, the northern and southern hemispheres lean to and from the sun, and days and nights of unequal length are experienced, the main cause of that diversity of seasons, which is so refreshing by contrast, convenient to mark the course of time, and subservient to the general well-being of plants, animals, and man.

A glance at the annexed sketch will show how the obliquity and constant parallelism of the earth's axis cause the several portions of the surface to receive varying amounts of the solar influence in different parts of the terrestrial orbit. At the vernal and autumnal equinoxes, in March and September, the sun shines equally upon the earth from pole to pole; and the daily rotation distributes equal portions of light and darkness over the globe. But at the summer solstice, in June, the northern hemisphere, being most inclined towards the sun, has its longest days and shortest nights; while at the winter solstice, in December, being most inclined from the sun, it has its shortest days and longest nights. The same effects follow from the same cause in the southern hemisphere, but at a different period; for as we pass from summer to winter, the inhabitants of southern zones are passing from winter to summer.

Among the physical characteristics of our planet, superficially considered, the most prominent and

distinguishing is its division into land and water. These components of the surface occur in very unequal proportions, and are inost irregularly distributed. According to usual estimates, the waters have the dominion over two-thirds of the globe, and of the remaining third, or the dry land, by far the largest amount is found in the northern hemisphere. We can assign no reason for this unequal proportion and irregular distribution, but contentedly fall back upon the sacred record: "And God said, Let the waters under the heaven be gathered together unto one place, and let the dry land appear: and it was so. And God called the dry land Earth; and the gathering together of the waters called he Seas: and God saw that it was good.” While the habitable parts of the earth are chiefly in the northern hemisphere, they are also to the greatest extent in the temperate zone-an arrangement of the first importance, as being favourable to the development. of energetic populations. The Esquimaux, Laplander, and Samoiede, represent man as an arctic dweller; the Negro, Hindoo, and Polynesian, as a tropical inhabitant: and, as far as history throws its light upon the past condition of the human race, all these families have been as they now are, far inferior in intellectual vigour and social improvement, to the nations subject to the climatic influences of the broad intermediate zone, the Greek, Roman, Frank, and Anglo-Saxon.

As the dry land is distinguished from the waters of the ocean by elevation, so its most remarkable external features are the immediate results of upheaving forces, exhibited in the phenomena of mountains and hills. These inequalities are endlessly varied in their aspect and outline, and render the landscapes of nature highly impressive, picturesque, or beautiful, by their diversity.