MOON’S APPEARANCE.--Astronomers have indulged their imagination to such a degree that the Moon has been considered to be a solid, opaque, spherical world, having mountains, valleys, lakes, volcanic craters, and other conditions analogous to the surface of the earth. So far has this fancy been carried, that the whole visible disc has been mapped out, and special names given to its various peculiarities, as though they had been carefully observed and measured by a party of terrestrial ordnance surveyors. All this has been done in direct opposition to the fact that whoever looks, without previous bias, through a powerful telescope at the Moon’s surface, will be puzzled to say what it is really like, or how to compare it with anything known. The comparison which may be made, will depend greatly upon the state of mind of the observer. It is well known that persons looking at the rough bark of a tree, or at the irregular lines or veins in certain kinds of marble and stone, or gazing at the red embers in a dull fire, will, according to the degree of activity of the imagination, be able to see different forms, even the outlines of animals and human faces. It is in this way that persons may fancy that the Moon’s surface is broken up into hills and valleys and other arrangements such as are found on earth. But that anything really similar to the surface of our own world is anywhere visible upon the Moon is altogether fallacious. This is admitted by some of those who have written upon the subject “Some persons when they look into a telescope for the first time, having heard that mountains are to be seen, and discovering nothing but these (previously described) unmeaning figures, break off in disappointment, and have their faith in these things rather diminished than increased. I would advise, therefore, before the student takes even his _first view_ of the Moon through a telescope, to form as clear an idea as he can how mountains, and valleys, and caverns situated at such a distance _ought_ to look, and by what marks they may be recognised. Let him seize, if possible, the most favourable periods (about the time of the first quarter), and previously _learn from drawings_ and explanations how to _interpret_ everything he sees.”[31] “Whenever we exhibit celestial objects to inexperienced observers it is usual to precede the view with good _drawings_ of the objects, accompanied by an explanation of what each appearance exhibited in the telescope _indicates_. The novice is told that mountains and valleys can be seen in the Moon by the aid of the telescope; but on looking he sees a confused mass of light and shade, and _nothing_ which _looks_ to him _like either mountains or valleys_! Had his attention been previously directed to a plain _drawing_ of the Moon, and each particular appearance _interpreted_ to him, he would then have looked through the telescope with intelligence and satisfaction!”[32] Thus it is admitted by those who teach that the