Earth's hemispheres

“ The two general masses of air proceeding from both hemispheres towards the equator, as they advance are constantly deflected [Pg 514] more and more towards the east, by reason of the earth’s rotation; that from the southern hemisphere, originally a south wind, is made to veer more and more towards the east ”

“ If it did not, the proportion of land and water, and consequently of plants and warm-blooded animals, being so different in the two hemispheres, we might imagine that the constituents of the atmosphere in them would, in the course of ages, probably become different also, and that consequently, in such a case, man could not safely pass from one hemisphere to the other. ”

“ Our planet has two envelopes, of which one, which is general — the atmosphere — is composed of an elastic fluid, and the other — the sea — is only locally distributed, surrounding, and therefore modifying, the form of the land. These two envelopes of air and sea constitute a natural whole, on which depend the difference of climate on the earth's surface, according to the relative extension of the aqueous and solid parts, the form and aspect of the land, and the direction and elevation of mountain chains. ”

“ The quantity of heat peculiar to a planet is, however, a matter of such importance — being the result of its primitive condensation, and varying according to the nature and duration of the radiation — that the study of this subject may throw some degree of light on the history of the atmosphere, and the distribution of the organic bodies imbedded in the solid crust of the earth. ”

“ If the surface of the Earth consisted of one and the same homogeneous fluid mass, or of strata of rock having the same color, density, smoothness, and power of absorbing heat from the solar rays, and of radiating it in a similar manner through the atmosphere, the isothermal, isotheral, and isochimenal lines would all be parallel to the equator. ”

“ The planetary system, in its relations of absolute size and relative position of the axes, density, time of rotation, and different degrees of eccentricity of the orbits, does not appear to offer to our apprehension any stronger evidence of a natural necessity than the proportion observed in the distribution of land and water on the Earth, the configuration of continents, or the height of mountain chains. In these respects we can discover no common law in the regions of space or in the inequalities of the earth's crust. ”

“ The increase of glaciers in one hemisphere would not only modify adjacent sediments directly, but, by adding matter on that side, would make a small difference in the position of the earth’s center of gravity. The ocean would move somewhat toward the weighted hemisphere, encroaching on some coasts and drawing down on others ”

“ For as the quiet and equilibrium of the parts of the earth and water with respect to the centre of gravity consist in the equal tendencies of the opposite parts towards the same centre, it follows that the sinuses or receptacles of water in the one half are nearly proportioned in their position and other respects to those of the other. From all which it follows, that in the southern hemisphere there is an uncovered surface of land correspondent, or nearly so, to that which has been discovered in the northern hemisphere. ”

“ From all this we obtain, as the most probable solution of the problem of the constitution of the interior parts of the earth, that the substances therein occurring have such analogies to those now seen near the surface, that they would have been subjected to very much greater condensation than they have suffered,—the globe would have been denser than it is,—were it not for the expansive influence of heat in the interior of the planetary mass. ”

“ Suppose, now, that 29,000,000 cold, solid globes, each of about the same mass as the moon, and amounting in all to a total mass equal to the sun’s, are scattered as uniformly as possible on a spherical surface of radius equal to one hundred times the radius of the earth’s orbit, and that they are left absolutely at rest in that position. ”

“ Therefore the Sun, Planets, and Stars rise every day, and ascend perpendicularly above the Horizon for six hours, and passing over the Meridian, descend in the same manner for the six following hours; then set in the Horizon, and continue twelve hours below it. Consequently at the Equator the days and nights are equally long throughout the year. When the observer is in the situation e, he sees the Hemisphere SEN; but in twelve hours after, he is carried half round the Earth’s Axis to q, and then the Hemisphere SQN becomes visible to him ”

“ The point is that in each case—that of a solidified globe like the earth, surrounded by a comparatively rare atmosphere; that of a partially cooled globe, like Jupiter, enveloped in a dense atmosphere of great depth; and that of a completely gaseous globe like the sun, possessing a sort of shell of partly condensed gases—certain regions near the equator are those in which the greatest disturbance is visible, and in every case, probably, the force of rotation is a powerful factor in the production of these zones of commotion. ”

“ The elevation of continents is still progressing slowly, and is being compensated for at some definite points by a perceptible sinking. All geognostic phenomena indicate a periodical alteration of activity in the interior of our planet. Probability of new elevations of ridges — p. 293-301 and notes.
g. The solid surface of the earth has two envelopes, one liquid, and the other aeriform. Contrasts and analogies which these envelopes — the sea and the atmosphere — present in their conditions of aggregation and electricity, and in their relations of currents and temperature. ”

“ In the bygone era of which we are speaking the pressure of the atmosphere on the water's surface was 700 lb. or 800 lb. to the square inch; and therefore it could be heated up to a high temperature without evaporating rapidly.
Another thing began to happen in those days. All bodies in space attract one another; the Sun attracts its planets; the planets attract the Sun and their satellites; and the satellites in their turn attract the planets. Ages before the earth had a moon these forces were at work. ”

“ On the other hand, as an equal portion of the globe is at all times acted upon directly by the sun’s rays, the internal contents of that globe must be always subject to the same degree of heat, excepting such variations as may be occasionally produced by the direct rays of the sun admitted through the polar openings. Of this fact we had evidence on the external world, where, in the most intense cold weather, we had but to penetrate a short distance into the earth to escape its influence. ”

“ Each hemisphere receives from the sun the same amount of heat.—The earth is nearer to the sun in the summer of the southern hemisphere than it is in the summer of the northern; consequently, it has been held that one hemisphere annually receives more heat than the other. ”

“ In this hypothetical condition of the Earth's surface, the power of absorbing and emitting light and heat would every where be the same under the same latitudes. The mathematical consideration of climate, which does not exclude the supposition of the existence of currents of heat in the interior, or in the external crust of the earth, nor of the propagation of heat by atmospheric currents, proceeds from this mean, and, as it were, primitive condition. ”

“ I shall answer, by the same causes, and by the same means as it exists on the terrestrial globe, although composed of stone, gres, marble, iron, and glass. There are other planets like our globe, whose principal is one of these matters; but the external causes will soon have altered its superficial strata, and according to the different degrees of heat or cold, dryness or humidity, they will have converted this matter into a fertile earth proper to receive the seeds of organized nature, which only needs heat and moisture to develope itself. ”

“ If we imagine an observer contemplating the earth from a « 58 » convenient distance in space, and scrutinizing its features as it rolls before him, we may suppose him to be struck with the fact that eleven-sixteenths of its surface are covered with water, and that the land is so unequally distributed that from one point of view he would see a hemisphere almost exclusively oceanic, while nearly the whole of the dry land is gathered in the opposite hemisphere. ”

“ An argument for the Earth’s convexity is thought by many to be found in the following facts:—“Fluid or semi-fluid substances in a state of motion invariably assume the globular form, as rain, hail, dew, mercury, and melted lead, which, poured from a great height becomes divided into spherical masses, as in the manufacture of small shot, &c.” “There is abundant evidence from geology that the Earth has been a fluid or semi-fluid mass, and it could not, therefore, continue in a state of motion through space without becoming spherical.” ”

“ Still, again, let us conceive of a sphere, but this time with a radius—not of ten millions of years of light’s flight, which would contain as many earths as drops in 1300 quintillions of such oceans, a number equalling more than half the drops in an ocean that contained 45 millions of cubic miles—but we will take less than ten minutes of light’s flight with a radius of 100 millions of miles, which is a little more than the distance from the earth to the sun. We find that this sphere would contain 15 trillions of earths ”

“ The laws of conservation may not be violated: the earth will respond.
How are the Spheres constructed?
The constitution of these two retro-acting spheres, and consequently of all the others of [Pg 26] the heavenly host, [3] at this point demands our attention. How are the spheres made up? How speaks the earth? The earth with which we are familiar—our sample—is formed of a slight crust, a core, to a greater or less extent and degree incandescent, and measuring 250,000 millions of cubic miles in dimensions, also an envelope which we call the atmosphere. ”

“ The figure of the earth, even on the ocean, is irregular, in consequence of the greater preponderance of land—and hence greater density—in the northern hemisphere. These irregularities are often very perplexing in making exact geodetic measurements. ”

“ By laws, the origin of which we have not yet traced, the condition of the diffused heat was changed, and the particles of the gaseous matter, condensed and agglomerated by attraction, into a series of planets, of which our earth is the third in point of size. That the earth has undergone vast changes, is evident to the most superficial geological student. ”

“ By methods, the history and description of which we have not here sufficient space to give, it has been proved that the earth is, in form, a globe, or more strictly an ellipsoid, slightly drawn in at the poles and swollen round the equator. The polar diameter is 7899 miles, and the equatorial diameter 7926 miles, the difference amounting to only 27 miles. Thus, for ordinary purposes, we may regard the earth as being a true sphere. ”

“ Outside the Earth's orbit, or at least outside Mars and the small Planetoids, there is, in the planets, apparently, no solid matter; or rather, if there be, there is a vast preponderance of watery and vaporous matter. Inside the Earth's orbit, we see, in the planets, no traces of water or vapor, or gas; but solid matter, about the density of terrestrial matter. The Earth, alone, is placed at the border where the conditions of life are combined; ground to stand upon; air to breathe ”

“ The planet's mass is expanded by the heat; large portions which at ordinary temperatures would be solid are liquified or even vaporised; matters which are liquid on our earth are vaporised; and, in fine, the planet assumes (as seen from our distant station) the appearance of being very much larger than it really is. We measure not the true globe, which, for aught that is known, may be exceedingly dense, but the dimensions of cloud-layers floating high in the planet's atmosphere. ”

“ The rotation of the earth on its axis forces the terrestrial atmosphere, by its centrifugal motion, in undue proportion, around the equatorial belt, causing the same sort of atmospheric thinning at the poles which we see in the solar photosphere at its corresponding parts. ”

“ Since it is highly probable that the oscillatory movements of the soil, and the rising and sinking of the upper surface, were more strongly marked in the early periods of our planet than at present, we shall be less surprised to find in the interior of continents some few portions of the earth's surface lying below the general level of existing seas. ”

“ To move the earth nearer to, or more distant from the sun, is an impossibility; but it has been argued that those planets which are near to the sun must possess a temperature which would melt our solid rocks, and vaporize the ocean,—while Uranus and Neptune must, from their distance from the source of heat, have so small an amount, that water must become solid as the rock, and such an atmosphere as that of the earth exist as a dense liquid. ”

“ Then, as the earth rolls on its annual journey, that which was at one time the cooler becomes the warmer hemisphere, and in its turn sinks as far below the average magnetic intensity as it before had stood above it, while the other hemisphere changes its magnetic condition from less to more intense. ”

“ As we have already remarked, one hemisphere of the earth (whether we divide the sphere through the equator or through the meridian of Teneriffe) has a much greater expansion of elevated land than the opposite one: these two vast ocean-girt tracts of land, which we term the eastern and western, or the Old and New Continents, present, however, conjointly with the most striking contrasts of configuration and position of their axes, some similarities of form, especially with reference to the mutual relations of their opposite coasts. ”