of new stars successively appear in the heavens, in the quarter to which we are advancing, while many of those in the opposite quarter gradually disappear; which could not happen if the earth were a plane in that direction, like the longitudinal surface of a cylinder: for, in this case, we should see all the stars of the heavens, from the North pole to the South, on whatever portion of the cylindrical surface we were supposed to be placed. This might be illustrated by surrounding a terrestrial globe, or any other ball, with a large hoop or circle, about twice or thrice the diameter of the globe, on which some of the stars might be represented. This circle might be made either of wood or pasteboard, and the globe within it connected with a moveable plane to represent the horizon, as exhibited in the following figure.

In this figure, the inner circle represents the earth; A, the North pole, and B, the South; and the larger circle, E C F D, a portion of the celestial sphere. It is evident, that if a person be placed at the equator at G, he will see all the stars above the horizon C D, in the hemisphere D F C. If he move to the point H, 45 degrees nearer to the North pole, the moveable plane C D, may be moved in the direction E F, to represent the horizon of that place, when it will evidently appear that he has now lost sight of all the stars situated between F and D, and that the polestar C, which, in his former position, was in his horizon, is now elevated 45 degrees above it. In a similar manner it might be shown that no such difference in the aspect of the starry heavens could take place, in travelling from South to North, or from North to South, were the earth of the form of a cylinder; and consequently, that the fact above stated proves the rotundity of the earth in that direction.

That the earth, considered as a whole, notwithstanding the irregularities caused by its mountains and vales, is of the figure of a sphere, may be illustrated from the phenomenon exhibited during the progress of an eclipse of the moon. An explanation of a lunar eclipse, accompanied with familiar illustrations, will be requisite to be given, before the proof of the globular figure of the earth be deduced from this phenomenon. Let the flame of a candle or gas-lamp represent the sun, and a wooden ball, supported by a wire, represent the earth; and let a circle, somewhat less than the diameter of the ball, be drawn on a piece of pasteboard, and coloured, to represent the moon. Let them be placed at a moderate distance from each other, and nearly in a straight line, and let the pupils mark the curve of the shadow of the ball on the circle representing the moon, and that there is no body but one of the figure of a globe that can project a circular

shadow in every direction; for, although a counter or a shilling will cast a circular shadow in one direction, yet in every other direction it is either an oval or a straight line. Hence the conclusion is easily deduced, that, if the shadow of the earth falling on the moon is the cause of an eclipse of that orb, and if this shadow, so far as it is seen, is always a portion of a circle, the earth, as a whole, must be nearly of a globular figure. In order to render such explanations clear and impressive-when a visible eclipse of the moon takes place, young persons should be directed to observe such a phenomenon with attention-to mark the figure of the earth's shadow when it first enters on the eastern margin of the moon-before it leaves its western edge—and during the whole of its progress along the disk, if it happen to be a partial eclipse of the moon; and, although they be not directly engaged in geographical studies at the time, yet such observations will afterwards prepare them for understanding such explanations as now suggested. Such minute illustrations, so far from being superfluous or unnecessary, are esentially requisite for producing in the minds of the young a rational conviction of the rotundity of the earth. I have known young ladies, and gentlemen too, who had passed through a scholastic course of geography, and yet could assign no other reason for their believing that the earth is globular, than this, "That their teacher told them so, and showed them a representation of it by the artificial globe." Besides, such specific explanations and illustrations tend to exercise the reasoning powers of the young, and to bring to their view a variety of incidental facts and circumstances connected with the subject, and thus their store of general information is gradually increased.

Having, by such methods as the above, produced a clear conviction of the spherical form of the earth, the next step might be to convey an impressive idea of its magnitude. For this purpose, let a class of young persons be conducted to an eminence, where they might have a distinct view of a landscape stretching about eight miles in every direction. Let their attention be particularly directed to the various objects which compose the scene before them; let them be directed to consider the vast mass of materials contained in the hills or mountains which form a portion of the view-the millions of labourers, and the number of years which it would be requisite to reduce the whole landscape to a perfect level, the number of trees and shrubs of every kind contained within the range of their view-the almost innumerable millions of flowers of every hue, stalks of corn, blades of grass, mosses almost invisible to the naked eye, and vegetables of every descrip

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tion, which cover every portion of the landscape-the cattle, sheep horses, dogs, and other quadrupeds, and the multitudes of birds worms, flying and creeping insects, and microscopic animalculæ, which no man can number, comprehended within the limits of their view-the number of houses and human beings in the towns, villages, and hamlets, which are scattered around, and the labours in which they are employed-the mass of waters in the rivers, and in that portion of the ocean which lies before them, (if such objects be in view,) and the numerous tribes of fishes which glide through the watery element. Let them be directed to consider the time and exertions which would be requisite to travel to the most distant part of the landscape, to go quite round it, and to cross it in forty or fifty directions, so as to attain a more intimate inspection of the multifarious scenes and objects of which it is composed. Let certain general calculations be made of the number and magnitude of such objects, of the motion of the inanimate parts of nature, of the activities of animated beings, and of the quantity of matter which appears on every hand. Having impressed upon their minds, as clearly as possible, such ideas of the magnitude and variety of the scene before them, let them be informed that the landscape they are contemplating is about 50 miles in circumference, and that its surface contains 200 square miles; but, that the whole surface of the earth contains more than 196 millions of square miles, and, consequently, is nine hundred and eighty thousand times larger than all the objects they behold around them; so that they must conceive 980,000 landscapes as large as the one before them, before they can form an adequate idea of the magnitude of the earth. To impress this idea more deeply, they may likewise be told, that, were they to remain in the station they now occupy, ten hours every day, (the time usually allotted for daily labour,) and were a landscape of similar extent to that which they behold, to pass before their view every hour, till the whole extent and scenery of the terraqueous globe were brought under their observation, it would require more than two hundred and sixty-eight years before they could survey, even in this rapid and imperfect manner, the whole superficial dimensions and variegated scenery of the globe on which we dwell.

Their attention should likewise be directed to the solidity of the earth-that it is not a mere superficies, but contains within its bowels an immense and indescribable mass of matter, extending nearly 7900 or 8000 miles in every direction between the opposite portions of its circumference, amounting to more than 263 thousand millions of cubical miles. An idea of this enormous mass of materials may be communicated by such illustrations as

he following:-Suppose Mount Etna,-which ranks among the largest insulated mountains on the globe, and which contains around its sides 77 cities, towns, and villages, and 115,000 inhabitants, to be 120 miles in circumference around the base, about 10 miles in circumference near the top, and 2 miles in perpendicular altitude, and considering its figure to be nearly that of the frustrum of a cone, it will contain about 833 cubical miles, which is only the T..TT part of the solidity of the globe, reckoning it to contain 263,858,149,120 cubical miles; so that it would require more than three hundred millions of mountains, such as Etna, to form a mass equal to that of the terraqueous globe: and were these mountains placed side by side in a straight line, they would extend 12,100,097,574, or more than twelve thousand millions of miles; that is, more than six times the distance of Herschel, the remotest planet of our system. And were we to travel without intermission, till we reached the extremity of such a line of mountains, at the rate of 25 miles every hour, (the utmost speed which our steam-carriages have yet attained,) it would require fifty-five thousand, two hundred and fifty-one years, before the journey could be accomplished. And, were they arranged in circles, equal to the perimeter of the sun, they would go 4376 times round the circumference of that stupendous globe, and cover a great portion of its surface. Again, suppose that all the inhabitants of the earth were to be employed in removing a mass of materials equal to that of our globe; suppose all that are capable of labouring to be 200 millions, and that each person removes ten cubical yards in a day, it would require more than 1,970,956,164, or, one thousand nine hundred and seventy millions, nine hundred and fifty-six thousand, one hundred and sixtyfour years, before such an operation could be completed; which is more than 337,550 times the number of years which have elapsed since the Mosaic creation.

It is of some importance, that, by such illustrations, we endeavour to convey to the minds of the young a luminous and impressive idea of the magnitude of the globe on which we dwell. For it is the only standard, or scale of magnitude, by which we are enabled to form a conception of the bulk of the sun, and some of the more magnificent globes of the solar system, and of the immensity of the universe. If we entertain imperfect and contracted conceptions of the size of our globe, we shall be led to entertain similar contracted views of the celestial orbs, and of the amplitudes of creation. No adequate conception of the magnitude of our world can be conveyed to the young, by merely telling them that it is 8000 miles in diameter, and 25,000 in ci