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INTRODUCTION.

THE subject of these lectures is Geography in its most enlarged and comprehensive sense. It will be necessary to preface them with some general observations, which shall serve to indicate the scientific basis on which the discussion will rest. Our startingpoint will be with Nature herself and not with arbitrary geographical systems hitherto constructed.

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By the word Nature will be meant the entire Creation. grasping of Nature in all its objects and all its forces becomes, in conjunction with the agency of Time and Space, the comprehension of a great system. The inanimate creation may be represented under the term inorganic, the animate creation under the term organic. Yet there is not an absolute contrast between them; for in both there is ceaseless progress, no pause, but in a higher and comprehensive sense a cosmical life, the whole forming one great Organism, in which the inorganic world, so called, is only the foundation on which the animate creation stands.

To us, our own Earth is the most marked feature of Nature viewed on its inorganic side. To us it is the planet best known of all, or rather the only one closely known, the point whence we draw conclusions on the whole Universe, the resting ground for the glass that searches the Kosmos, to use Humboldt's word, discerning the place which the Earth holds in it, and prying into the mysteries of the entire creation. Our globe is one of the major planets of our system, all of which gird the sun with great elliptic orbits, midway in which is our own. There begins the first

popular division of the planets,-those that are within and those which are without our own orbit. This is one of the most simple of discriminations, one which we inherit from the ancients in an unmodified form. Humboldt retains this primary classification.

The external planets are those whose orbits embrace that of the Earth within their own. The minor planets are those whose orbits are embraced by that of the Earth. These are Mercury and Venus.

The ancients, counting both the sun and moon, reckoned only seven planets. At the end of the eighteenth century another was added, Uranus, an external planet. Through the instrumentality of improved telescopes, soon after, four minor ones were discovered, Ceres, Pallas, Juno, and Vesta; and by the still more perfect lenses recently introduced, and the assiduity and skill of astronomers, the number of these little planetary bodies, ranging between the orbits of Mars and Jupiter, has grown great. Beyond Saturn and Uranus is Neptune, discovered mathematically by Le Verrier, in Paris, and seen by Galle in Berlin, the 23d of September, 1846. To these (now eighty) planets may be added the twenty to thirty moons of our solar system, and a number of comets.

The middle position of the Earth's orbit is not without its consequences. The distance of the Earth from the Sun is, in round numbers, 92,000,000 of miles, nearly three times as far as that of Mercury, the planet nearest the Sun. Jupiter, on the other hand, is five times as far from the Sun as the Earth; Uranus about nineteen times as far, and Neptune about thirty-three times as far.

The time of the Earth's revolution around the Sun is also equally removed from the extremes; its year is 365 days; Mercury's being 87 days; Jupiter's 11 of our years; Uranus 84 years; and Neptune's 165 years.

The daily revolution of the Earth on its axis is also of only medium swiftness, consuming 24 hours. This, of course, controls the periods of waking and sleep of the entire animate creation on our globe. Some planets revolve slower, some more rapidly than our own; Jupiter's revolution, for example, is accomplished in little less than 10 hours. This extreme rapidity seems to account for the much greater flattening at the poles of the planets than the Earth exhibits, occasioned doubtless during the formation processes, while those immense revolving masses were passing from their primitive fluid state into the more rigid forms in which we know them. Of all the planets, however, the Earth has most perfectly retained the spherical shape; and the spherical form is in one sense a medium form; i.e. it is removed from all extremes of angularity, and so falls in with the analogies which I am endeavoring to establish, springing from

the position of the Earth's orbit midway between those of the inner and outer planets. According to Plato, the beauty of form lies in symmetry, and our Earth is the most symmetrical of planets, and, unquestionably, the spherical shape is the one best adapted to the display of the largest number of phenomena possible.

The variations from the spherical form, produced by elevations and depressions, are only of medium magnitude in our globe compared with many others in our system. On the smaller planet of Venus, for example, the mountains are thought to rise to a height of many miles, while five is the greatest altitude of ours. According to Mädler's conjectures, the mountains in our own moon rise to a height of over three miles, an altitude altogether out of proportion to the size of the moon as compared with the earth.

In respect to the number of its moons, too, our Earth is no extremist; it has but one: other planets, Mercury, Venus, Mars, have none. On the other hand, Jupiter has 4, Saturn 7, Uranus 6 at least, and doubtless more. The general law seems to be, the farther from the Sun the greater the number of moons; perhaps in the wonderful providence of God, to compensate the feeble light of those distant realms by the number of the reflecting bodies.

Now, summing up all that has been said, it will be seen that the Earth is equally far removed from every extreme. This fundamental classification, drawn from the place of its orbit in relation to those nearer the Sun or more distant from it, gives it a character which is felt and seen in many different things, and responds to analogies which it is not incorrect to mark. A medium is seen in all its attributes and relations: it is neither the largest nor the smallest of planets; neither the swiftest nor the slowest; neither the warmest nor the coldest; in nothing is it either at a minimum nor at a maximum point. And this very medium character brings the Earth into harmony with the system of which it forms a part; the symmetry of the one corresponding with the symmetry of the other, and specially fits it to become the temporary home of a race like ours, which makes the whole surface of the globe tributary during the short terrestrial life of man to his preparation for a celestial state of being. Our globe is certainly the only one of our system which could possibly be inhabited by man; and as his residence, and as the arena for his culture, it is worthy of being studied in all its features; no point is too trifling to be overlooked.

As man looks for a center to the system which evidently pertains to him, and in which our Earth plays no slight part, the Sun is clearly the source of a large share of what makes our life desirable. Thence we receive light, warmth, and indirectly, and yet directly too, life and the bloom of health. Nor can men, even if ignorant and degraded, help seeing the relation of the Sun to the Earth, and linking, in their rude thoughts, the heavens with the earth; and hence, before all higher Revelation, the worship of the Sun has been the primitive instinct of the oldest of nations.

Looking at the earth as simply one among the innumerable hosts of heaven, it, like each one of them, becomes to the imagination a mere point of light, a "star among stars." But, when we shift our point of view, and leaving the cosmical or universal for the special, for what pertains to the individual life, the mere point of light flames up into a great, busy world, full of phenomena demanding investigation and thought. And yet this world, so attractive in its multiplicity of details, is almost a chaos at the first sight; a confused and inextricable mass, so large, so high, so deep as to defy human effort to compass or master it. Science alone, the gift and the growth of centuries, can measure the field; science alone can enter it and reduce the chaos to a beautiful and orderly grouping, and make a perfect picture of the whole; it alone can dispel crude ideas and give truer ones in their stead. To the rude dweller on the plain, the earth seems a gigantic floor, as it did to many a tribe in the past, and as it does to-day to thousands of wondering Arabs. The South Sea Islander, in the Pacific, takes his island or island group to be the whole earth; the world he considers an endless ocean plain, from which the Sun arises, and, when the day is over, into which it sinks. And even within the pale of civilization itself, the ignorant Neapolitan lazzarone considers his gulf the center of the world.

As men advance in their inquiries, and, ascending the sides of mountains, look out over a larger tract, or find new lands across the seas, they do not outgrow their first idea, the world merely expands from the narrow homestead to a larger circle, such as the Romans used to call their orbis terrarum. The conception of the earth as a vast, unsupported ball, careering through the heavens, was the possession, slowly won, of such great minds as Pythagoras and Aristotle, and slowly found its way among the ideas which

whole nations accepted as true. Circumnavigators must sail around the globe and tell their story to the world before the conjectures of science could have real weight with the popular mind in a matter so remote from the crude speculations of the ignorant as this. And less than one century and a half ago (in 1727) another step was taken, and the theory was propounded by Newton, that the Earth is a spheroid and not a perfect sphere. Later investigations have determined that the spheroidal form is only an approximation to perfect accuracy, and that the Earth is a polyhedron, whose exact number of zodes has not yet been determined, and which may prove indeterminable. Bessel has assigned, as the great task of science for the coming century, to settle this question with perfect exactness. But what has been said is enough to indicate that in our knowledge, at present, certainly there is only progress, only approximation, no absolute exhaustion of the processes of discovery.

And just as in ruder lands each man looks at his own island, or village, as the center of the earth's circle, so the ancients looked at the earth as the pivot of the universe, the central point around which all the heavenly hosts revolve. That was the fundamental principle of that Ptolemaic system which was older than Ptolemy; held in the most ancient times in Arabia, Babylon, Persia, and India, but first luminously expanded in the proportions and with the dignity of a system by Ptolemy. Its outlines were, in one word, this: there are seven planets, the Moon, Mercury, Venus, the Sun, Mars, Jupiter, and Saturn; each has its own orbit, in which it is in a limited sense supreme, but they all revolve around the common center, the Earth. Beyond the seven, and including them all, is the Firmament, in which the other stars stand like golden nails in an imperishable floor; the whole vast external Firmament is opaque and motionless.

The Ptolemaic system won and held the greatest regard in the ancient world. Mohammed established it in the Koran as a truth of religion. The advance of science revealed the falseness of the Ptolemaic scheme of the universe, and demonstrated the fact that the stars of heaven are not mere torch-bearers for us, and mere interpreters of human destinies, but are worlds like our own, our earth being but one of numberless thousands equally worthy of the Common Creator. The Copernican system, which was to re-create the whole domain of science, wrought this great change. The

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