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desired, when in the woods, to ascertain the di- | Around the Sun, a sphere 880,000 miles in rection from which the wind is blowing. We diameter, there revolve a number of globes; may need it as a guide. There may not be sufficient air stirring to drift away a light object like a straw. Under these circumstances foresters, having wetted the finger, hold it upward at arm's-length. A gentle breeze causes the moisture to evaporate more rapidly on the side it first strikes, and the direction is at once indicated by the coldness of that side. So also in the case of the porous earthen-ware vessels used in southern climates for keeping water cool. The fluid that soaks through the earthen-ware, evaporating from the outside, keeps the temperature of the water much below that of the surrounding air.

Lastly, as regards food but little requires to be said. All know from hard experience how necessary it is. If we do not eat we soon become emaciated and die after a short interval.

What is the cause of this wasting away, and why can we not resist it by the will? We have already learned that air is essential to our well-being, because we must have a burning continually going on in the body. But we must also have a fuel to burn, and this fuel is either the food or portions of the body that have been made out of it. If we do not eat and resupply the parts that are consumed our weight becomes daily less and less, as we see in wasting fevers, until, when a certain point is attained, we die of cold.

The food we require is produced by plants, the remark applying even to meat, which has been extracted from plants by oxen, sheep, etc. That it is combustible can be proved by experiment. A piece of meat or bread, if placed in the fire, burns away, leaving only a little ash; the mass of it having united with oxygen and disappeared in a gaseous form. The same would have happened had it been eaten, though the burning would have been slower and without flame.

It is the combustibility of stimulants, such as whisky and brandy, that renders them valuable in low fevers. Nowadays the treatment in such cases is to give the patient as much liquor as he can bear without becoming intoxicated; it burns away within him to produce the animal heat he requires, and so saves him to a certain extent from the emaciation that would be produced by the burning of his body. For the healthful performance of the functions of the system a temperature of nearly 100 degrees must be maintained by man; if he becomes much cooler than this he will die of cold. The sensation of cold piercing to the very marrow of the bones, so keenly felt by those ascending high mountains, is due to the attenuated state of the air in such localities; not enough can be taken in by the lungs at each breath to keep the body burning at a proper

rate.

We are now ready to glance for a few moments at the construction of the solar system.

some, the more important, called planets; some the moons or satellites of these planets; and the rest asteroids, or else, if very small, aerolites or meteors. The planets are, of course, the bodies most likely to prove interesting to us, and they may therefore be profitably enumerated. The nearest to the Sun is Mercury, 37 millions of miles distant; next comes Venus, 68 millions of miles distant; then the Earth, 95 millions of miles. Outside of us, or farther from the Sun, are Mars, 142 millions of miles from that luminary; Jupiter, 485 millions; Saturn, 900 millions; Uranus, 1800 millions; and Neptune, 3000 millions.

An idea of the comparative size of these bodies and their distances from the Sun may be gained from a table constructed by Sir John Herschel :

The Sun, a globe two feet in diameter.
Mercury, a mustard seed, diameter of orbit 164 feet.

Venus, a pea, diameter of orbit 284 feet.
The Earth, a larger pea, diameter of orbit 430 feet.
Mars, a large pin's head, diameter of orbit 654 feet.
Jupiter, an orange, diameter of orbit half a mile.
Saturn, a small orange, diameter of orbit one and one-

fifth mile.

Uranus, a cherry, diameter of orbit a mile and a half. Neptune, a plum, diameter of orbit two and a half miles.

The nearest Fixed Star, distance fifteen thousand m les.

If we can succeed in rendering it probable that on any of these bodies there is life, we shall be led at once to extend the sphere of animated nature infinitely. For we know that each of the countless multitudes of fixed stars, which delight our gaze on a clear evening, is a sun, shining, as our sun does, by virtue of its own light. At distances vastly greater than these are collections of stars, which, though they may in reality be separated as far from one another as the nearest fixed star is from us, yet seem to be closely packed together. These, the resolvable nebulæ, are stellar systems of prodigious extent. Many are not bright enough to affect the naked eye; and who shall say what immense numbers there may be invisible even with the telescope?

We may argue from analogy that all these suns, many of them larger than ours, are surrounded by trains of planets, revolving around them at various distances. If on any of the planets of our solar system life can be maintained, why not on those planets too? And does it not seem reasonable to suppose that all those bodies have been created for some other purpose than merely occasionally to illuminate our skies? Is this little speck in the universc where we are existing, and which is visible to only two or three of its immediate neighbors, the only seat of life?

"Each of these stars is a religious house;

I saw their altars smoke, their incense ri-e,
And heard hosannas ring through every sphere.
The great Proprietor's all-bounteous hand
Leaves nothing waste, but sows these fiery fields
With seeds of reason, which to virtues rise
Beneath his genial ray."

The first planet outside of the Earth-Mars is 50 millions of miles more distant from the Sun than we are. When it is favorably situated its surface can be closely scanned through the telescope. It seems to me to be by far the most interesting object in the heavens from its similarity to the Earth.

But you may say, How do you know that we must of course presume that they are unthose other worlds are not composed of such inhabited. materials that life is there impossible? Science has within the last few years stretched her hand across the almost immeasurable distances which separate us from the fixed stars, and told us that there are in them many of the substances with which we are here familiar. It would lead us too far from our subject to indicate the manner in which so grand a result has been reached. I can only tell you that we are able, by examining the light coming from the stars by a prism, to detect their composition, just as if we had fragments of them in our laboratories. Spectrum analysis has made the chemist's arms millions of millions of miles long.

Let us examine our planetary neighbors, and ascertain what are the chances of inhabitation upon them. The two planets that are nearer to the Sun than the Earth may be dismissed at once. The most reliable researches lead astronomers to suppose that Mercury and Venus are too hot to permit of either animal or vegetable life. Venus is regarded as being red-hot, and Mercury even hotter. If such be the case,

In the summer of 1862, when my large telescope had been completed, Mars was often observed, and showed appearances some of which are represented in the adjoining cut drawn by Professor Phillips. There was visible, in the first place, an expanse of water covering a large proportion of the Southern hemisphere, and of a greenish hue. The remaining parts, at the upper portion of the picture, are land of a reddish tinge, assuming the figure of continents. In addition-and this is a point of peculiar interest-at the north and south polar regions there are accumulations of snow, presenting appearances strictly analagous to those at the arctic and antarctic regions of our globe. The snow spot at the South Pole is here shown; the North Pole is invisible.

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Let us recall the condition of our Northern | a warm summer and a cold snowy winter. As Hemisphere. In winter snow falls and covers his year is almost equal to two of ours, each it with a white envelope, extending for six season is twice as long as with us. months, to a latitude certainly as low as the northern border of the United States. If the earth were viewed from a distance, there would scem to be a white spot surrounding the north pole. As summer came on this white spot would begin to disappear, melting away at its southern border, and to the distant observer would seem quite insignificant at midsummer. Precisely a similar phenomenon is witnessed at the poles of Mars, and hence we see that he too has seasons similar in their nature to ours, VOL. XXXIII.-No. 193.-D

There is still another point of resemblance. On watching the planet Mars carefully through a large telescope, we observe that his surface is not always the same in appearance, but that dark spots occasionally are visible, and cover large parts of it. They are variable in extent and outline. These are obviously clouds floating in his atmosphere, the source whence falls the winter's snow and, doubtless, though we do not see it, the summer's rain.

There is then another body, revolving as the

Earth does around the Sun, as far as we can judge suited to the abode of sentient beings. It has air, water, alternations of seasons, snow, rain, and, possibly, vegetation. It is, to be sure, half as far again as we are from the Sun, the source of light and heat, but is not cold enough to be perpetually frozen and therefore

sterile.

The question at once arises, do you discover upon its surface any traces of the works of man, are there tokens of great cities and visible lines of road? As our telescopes are at present, we are too far off to see any of these things, even if they are there. No power yet applied would enable us to distinguish at this distance an object 50 miles square. What we may do in the future it is, of course, impossible to predict. One of the greatest obstacles to distinct vision is our own atmosphere. Its currents and motions tend to confuse the outlines of objects, and, according to my experience, a whole year may pass without the occurrence of more than one good night. The only remedy is to carry the telescope as high up on a mountain as possible, so as to leave below the more injurious portions of the atmosphere. It might be possible to work 15,000 feet above the sea in the neighborhood of the equator.

In the list of planets given, four large ones were placed outside of Mars, that is, farther from the Sun. But with these we have not time to deal. The only remark necessary to be made is, that on two of them, Jupiter and Saturn, there is reason to believe both air and water exist.

But you will say why is the Moon overlooked all this time? She is close to the Earth, and must possess similar conditions as to light and heat; are not the probabilities strong that she is inhabited?

A few years ago there was published in the daily papers of this city a description of pretended discoveries in the Moon which excited at the time a great deal of attention. It was stated that Sir John Herschel had taken to the Cape of Good Hope a lens of 24 feet diameter, and with it had seen a variety of objects, animals, buildings, and even a species of men. The human beings were described as having ,wings like a bat, but nevertheless they evidently conversed and were familiar with polite actions, such as peeling fruit for one another. This, "the Moon Hoax" as it is termed, imposed on very many persons, and when its falsity was discovered, left behind an unfortunate skepticism as to statements that are really true.

Let us examine the actual state of the Moon, and see what the probabilities of habitation are. We will ascertain the more prominent peculiarities, and then I will show you some of them by the aid of a photograph enlarged by Starr's calcium light and lens.

On looking at the Moon with the naked eye certain markings are visible, dark and white spots. Before the invention of the telescope

the dark spots were called seas, the bright ones land. But we now know that there is not any large collection of water on the side of the Moon that is turned toward us. Why is that expression, "the side turned toward us," used? We only see one hemisphere of the Moon; one side is perpetually turned away from us.

A telescope of even moderate power shows at once, particularly if the Moon be only six or eight "days old," that her surface is very rugged and much broken. The northern part is less rugged than the southern, and we see that the so-called seas are great valleys many hundred miles across. They may be the basins in which seas formerly were, but they now contain no water. Nor do we find on any part of the visible side tokens of either air or water. Recalling the fact that no animal or plant can live without these essential materials, we are convinced at once that there is no use in searching for inhabitants there.

But there are strong reasons for believing that water must exist somewhere on the Moon. That fluid enters as an ingredient into the composition of rocks, and it is a cause of volcanic eruptions. The face of the Moon is largely composed of abrupt rocky precipices, and volcanic action has been in past ages frequent on it.

We are sure that the water is not floating about in the shape of dense clouds, for we should see them easily enough through our telescopes, and collections of ice and snow would now and then make their appearance. Of late, however, it has been demonstrated mathematically, that the side nearest to us is farther away from the Moon's centre of gravity than the more distant side. It is, so to speak, down hill from this face to that, the amount of declivity being about 30 miles. So there might be air and water 30 miles deep on the opposite side, and we should not see them here. There may be inhabitants there, but our chances of making their acquaintance are small enough. It was at one time proposed by some enthusiastic astronomers to communicate with the inhabitants of the Moon by erecting on one of the great plains of Asia stone structures representing a certain geometrical problem, "in a right-angled triangle the square of the hypothenuse is equal to the sum of the squares of the other two sides." It was hoped that if there were intelligent inhabitants on the Moon who had discovered the truths of geometry they would answer by marking out on one of their plains some other problem in response.

We see from our physiological investigation of the subject how futile such an attempt would have been. The inhabitants on the far side of the Moon, if there are any such, never see the Earth unless it may be low down in the horizon and dimly. If they existed on the centre of this side, they would see her as a glorious globe, fourteen times as large as the Moon seems to us, shining with a pure light, variegated with clouds, and revolving like a gigantic

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