seems to reverse the question with which we set out, and to make the difficulty consist in believing, not that life in some shape exists upon our fellow planets, but that they can possibly be destitute of it. The interest of such enquiries passes beyond their mere astronomical import, for they touch our conceptions of God's greatness. Which of us does not long to be able reasonably to cherish the thought that, far away from this speck of Earth in the remote realms of space, we behold worlds inhabited by beings who, it may be, are privileged like ourselves to know their Creator, and to bless, praise, and magnify Him for ever?

The

We turn towards our nearest neighbour in the solar system with a sentiment bordering on familiar affection. We speak of it emphatically as "our moon." The sun we share with other planets, but this beauteous orb belongs exclusively to ourselves. Transmitting to each other but little warmth, we yet cheer up the darkness of each other's nights by liberally reflecting the rays which each receives from the sun. Like loyal friends we give and we take to our mutual advantage; and, as the Earth is the larger reflecting body of the two, we repay with interest all the light we borrow. To young and old the moon is ever interesting and beautiful. infant questions it with delighted eye, and stretches out its tiny arms to play with or to catch it. From moonland have descended some of the mysterious legends of childhood. The boy soon learns to recognise "the man in the moon," and the familiar face roots itself in his imagination for life. Its gentle light is associated with many pleasures. We welcome its first curved streak in the west as a sign that our gloomy nights are past; we watch it to "the full" with ever-increasing admiration, and we part from it at last with regret and hope. Our very dogs salute it with their bark; a notice they bestow

on no other celestial object. Poised in the clear sky, or floating among the fleecy, tinted clouds, silvering the water or piercing through the trees-in every phase and aspect it is beautiful. Like an enchanter it casts the charm of picturesqueness over the meanest objects, and masses which look hard or ugly in the garish light of the sun mellow into beauty when touched by the power of the moonbeam.

The moon's journey round our earth-the lunar month is accomplished in a little more than twentynine days and a half. When interposed between the earth and sun she is invisible, because her dark side is turned towards us; but during nearly all the rest of her circuit she reflects a portion of the light received from the sun, and cheers our nights with brightness. The actual amount of light thus transmitted is small when compared with that which floods in upon us from the sun, being scarcely equivalent to the 300,000th part; and it has been calculated that were the whole heavens covered with full moons, it would not equal the light of the sun. The distance of the moon from the earth is nearly 240,000 miles, and an express train could easily clear the distance in 300 days.

Unlike the active Earth, which rotates on its axis every twenty-four hours, the moon turns herself round only once in twenty-seven days seven hours and fortyfour minutes. Everybody must have observed that the well-known features of "the man in the moon" never change; in other words, the same hemisphere of our satellite is always presented towards us. That this peculiarity is the result of the coincidence in point of time which exists between her axial rotation-constituting her day-and her orbital rotation round the Earth, which constitutes our month, may be easily illustrated by experiment. Thus, if a person move

slowly round a circular table, keeping his face, which we may suppose to represent the moon, always directed towards the centre of the table, where we may suppose the Earth to be placed, he will find that in making one complete circle his face has rotated or turned round once also. Such is precisely the relation between Earth and moon during the course of the month, and thus it may be easily understood why we always see the same side of the moon, notwithstanding her rotation.

As the moon revolves only once on her axis in the course of a month, it follows that during half of that time each hemisphere is turned towards the sun, and during the other half it is turned away from it:-the whole period forming one long day and one long night. The Lunarians, therefore, if any exist, must be subject to a very singular climate. During their long "half-month" day the surface must be scorched by a sun whose fierceness is tempered by no atmosphere; and this must be succeeded by a half-month" night, in which the sun is altogether absent, and the darkness is broken only by starlight. During the day the temperature will far transcend the hottest tropical climate, while in the night it will sink far below the greatest cold of the arctic regions.

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He who once fairly surveys the moon through a good telescope will never afterwards forget its aspect. It charms the eye with its beauty no less than it fascinates the imagination. A good pictorial chart or photograph gives an idea of it which wonderfully approaches nature, and it is as easy to trace upon it the various localities in the moon, as it is to follow upon a map the different features of the earth. If we look at the full moon we take, as it were, a bird's-eye view from a great height, which levels inequalities. Its disk presents a smiling, brilliant, yet softly lighted surface-a sunny land from which all gloom is banished. But both be

fore and after the full moon, when we see its features more in profile, a different tale is told. Here and there softly shaded plains are still to be noticed, but the chief part of the surface appears to have been fashioned by the most violent volcanic forces. It is scarred and rent, convulsed and burnt into an arid, cindery ruin. Serrated craters, some more than a hundred miles wide, are thickly dotted about, and enclosed within them are levels from whose centre cones of igneous origin shoot up. The brightest peaks, the darkest precipices, the most jagged ridges crowd this rugged picture. Το many minds the idea has suggested itself that some scathing doom has blighted the surface of our satellite, for nowhere else can nature match this aspect of desolation. Fancy rather than science tries to deal with such a scene. Some conjecture that it may be an Earth burnt up and destroyed by the outpouring of God's wrath. Others suppose that it is a comparatively recent world-a globe in a state of chaos-whose crust has not yet been worn down by the hand of time to fit it for the abode of living creatures. Destitute of life it doubtless appears to be at present, nor does its physical condition seem to fit it for ever becoming the abode of that kind of life which we see existing on our own globe. Amid such conjectures let us fall back with thankfulness upon what is certain. Cosmically considered it performs its part in upholding the balance of the solar system; and, in reference to the Earth, we know that it was created by Our Father "to rule the night," and in other ways to shed blessings on His children.

Many of the mountains in the moon have been measured by ingenious mathematical processes, and at least one has been found to attain a height of 26,691 feet, which, though not quite equal to that of our highest Himalayan or Andean peaks, is yet proportionately

higher, since the moon's diameter is little more than a fourth of that of the earth. When the rays of the sun fall obliquely upon them they appear bright on the side next the sun, and in dark shadow on the side turned away from it. Their peaked and jagged outline is best displayed along the inner margin of the crescent moon. Thus lunar mountains present in miniature an exact counterpart of the effects which sunlight produces on the mountains of the earth. In highland districts the rays are first caught by the loftiest peaks, then the side. next the sun is brightened, while the side turned away from it still remains in shade. Lastly, as the sun advances, the western slope becomes illuminated, and the eastern in its turn passes into darkness.

From the almost total absence of those effects that would necessarily result from the refraction of light, astronomers conclude either that the moon has no atmosphere, or that, if it exist, it must be as attenuated as the air in the vacuum of an air-pump. For the same, and for other reasons, it is to be inferred that water is wanting also. During the long moon-day of half a month, the sun's rays beat fiercely upon its surface, from which clouds of vapour would certainly be sent up if any water existed for them to act upon. The result would be to cover the moon with a nebulous screen impenetrable to vision,-a condition which is plainly inconsistent with the fact that whenever the earth's atmosphere is clear, we always see the moon with the same unvarying bright

ness.

The Earth and its satellite, as has been said, mutually interchange their good offices, and shine upon each other as moons. A curious illustration of this is seen when the dim outline of the rest of the moon fills up the hollow of the bright crescent, or when, in popular phrase, "the young moon has the old one in her arms." We all