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earth, then the weight of bodies on the planet, on that account alone, would be sixteen times greater. The weight, then, on the one score, would be sixteen times greater, and on the other, four times less; the result being that the actual weight under such circumstances, would be four times greater than upon the earth. Such are the principles by which may be calculated the weights of bodies upon the surfaces of the different planets. It has been found that the weights of bodies on the surfaces of Mercury, Venus, and Saturn, are nearly the same as upon the earth; that upon Mercury they are one half less, and on Jupiter three times more. Thus it is apparent that there are no very extreme deviations in weight, comparing the surface of one planet with another, and hence we are led to infer the probability of an organization not very different upon the several planets.

We have already explained by how easy means the great variety of light and warmth conveyed to the different planets by the sun may be practically equalized, by the adaptation of the organization of the eye, and the regulation of the density of the atmosphere. Since, however, this difference in the physical condition of the planets excites usually much attention, it may be well here, before closing this discourse, to enlarge somewhat further on this point.

The principles of optics prove that the sun's light will be less upon the planet Mars than upon the earth, in the proportion of one to two. Jupiter will receive about twenty-five times, and Saturn about one hundred times less warmth than the earth does, while the diminution in the case of the most remote planet, Herschel, will be nearly four hundred fold; on the other hand, Venus and Mercury, being nearer to the sun than the earth, the one will receive twice, and the other seven times, as much light and warmth as the earth does. The apparent magnitude of the sun to these planets will be in the same proportion. To Jupiter it will have an apparent diameter five times less than to the earth. To Saturn the diameter will be ten times less, and to the planet Herschel nearly twenty times less.

The apparent magnitude of the sun as we behold it is measured by an angle of about thirty minutes; consequently, to the inhabitants of the planet Herschel it will appear under an angle less than two minutes, or about three times the size of Jupiter when that planet appears the largest and brightest. We should, however, form a very erroneous estimate of the actual light of the sun under these circumstanes by these comparisons. It shines by its own light, whereas the objects with which it is attempted to be compared shine with reflected light. The full moon has the same apparent magnitude as the sun, the difference being that the one shines with direct, and the other with reflected light; how much is lost in splendor on this score may be judged, when we state that the light of the full moon is three hundred thousand times less than that of the sun; we may also form some guess at the effect of the sun's light, even at the most remote planet, Herschel, when it is stated that it gives a light equal nearly to that of a thousand full moons.

If we could actually behold the day of Saturn and Herschel on the one hand, and of Mercury and Venus on the other, we should be surprised how disproportionate to their numerical representation their apparent splendor would he. The eye is a bad photometer. În a solar eclipse, in which half the sun's disk is covered, we are scarcely sensible of diminished light; and even when the eclipse is nearly total-when only a thin crescent of the sun remains uncovered there is still the broad light of day, though very sensibly diminished in splendor. A thick covering of clouds upon the firmament produces an immense numerical diminution of the light of day, yet we suffer no inconvenience in being exposed to all the varying degrees of splendor between that and the unclouded radiance of a summer's sun.

How various may be the circumstances of climate and temperature in places receiving exactly the same influences from the sun's rays, will be apparent by a reference to the tropical regions of our own globe. There under the same influences of the same solar heat, we have in different elevations every variety of climate and temperature. On the general surface, near the elevation of the sea, we have the fierce climate of the torrid zone; we have only to ascend the mountains to a certain height, to behold the trees, fruits, and flowers, of the temperate zone; while at a still greater elevation, we encounter all the atmospheric phenomena and vegetable productions of the frigid zone. In the low valleys of the Andes are rich bananas and palms, while the elevated parts of the range produce oaks, firs, and the tribes common to the north of Europe. The oak flourishes on them at elevations varying from six to ten thousand feet. At fifteen thousand feet of height vegetation disappears, save the lichens, and then we enter the solitude of everlasting snow, in which every living thing disappears.

How easy, then, and how natural, is it not, to conceive that atmospheric arrangements like those which, under a tropical sun, produce at certain elevations the moderate temperature of our own climate-at others, less or greater, the fierce heat of the line, or the rigor of the poles-may be the means of modifying the varieties of effect which would be produced in different planets by their different distances from the sun!

Such is, then, the brief view which we offer of that vast body of analogy which leads the intelligent and reflecting mind, that loves to see the most exalted attributes of Divine power manifested throughout all parts of creation, to the conclusion that the planets are worlds, fulfilling in the economy of the universe the same functions, and are created by the same Divine hand, for the same moral purposes, and with the same destinies, as the earth.

THE SUN.

The most Interesting Object in the Firmament.-Its Distance.-How Measured.-Its Magnitude.How Ascertained.-Its Bulk and Weight.-Its Density.-Form.-Time of Rotation.-Spots.Its Physical Constitution.-Nature of the Spots.-Luminous Coating.-Its Thickness.-Probable Temperature of the Surface of the Sun.-Nature of its Luminous Matter.

THE SUN.

ALTHOUGH perhaps the moon is the object among the heavenly bodies which presents the subject of most interesting inquiry to the world in general, yet, to the thoughtful and contemplative mind, the Sun is undoubtedly one of vastly superior interest. The sun-the fountain of light and life to a family of circumvolving worlds-the inexhaustible store of genial warmth by which the countless tribes of organized beings that people these globes are sustainedthe physical bond whose predominating attraction gives stability, uniformity, and harmony, to the movements of the entire planetary system: to collect together in a brief compass the information which modern scientific research has supplied relating to this body, cannot be otherwise than an interesting and agreeable task.

DISTANCE OF THE SUN.

When we direct our inquiries to any object in the heavens, the first questions which present themselves, naturally to us are, "What is its distance, magnitude, motion, and position?" When we say that the distances of the bodies composing the solar system can be measured with the same degree of relative accuracy with which we ascertain the distances of bodies on the surface of the earth, those who are unaccustomed to investigations of this kind usually receive the statement with a certain degree of doubt and incredulity; they cannot conceive how such spaces can be accurately measured, or indeed measured at all. Thus, when they are told that the sun is at a distance from the earth amounting to nearly 100,000,000 of miles, the mind instantly revolts from the idea that such a space could be exactly ascertained and estimated. Yet, let us ask, why this difficulty? whence this incredulity? Is it because the distance thus measured is enormously great? Greater transcendently than any distance we are accustumed to contemplate upon our own globe? To this we reply that the magnitude of a distance or space does not constitute of itself any difficulty in its admeasurement. Nay, on the contrary, it is

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