The thousands of stars which spangle the heavens are all part of one "system;" but it has been found by the aid of the telescope that this system is but one out of many. Our system of stars occupies a space somewhat in the form of a thick lens or much-flattened sphere, but others are of very different forms, and some have but little regularity of form at all; our sun is one of the stars of this system. It is not known whether there are planets revolving round the other stars, the distance being far too great for any telescope to render them visible. Our sun occupies a somewhat central position in the system. The stars are classed into sizes, as first magnitude, second magnitude, &c., on to the thirteenth or fourteenth magnitude, but all beyond the fifth magnitude (by far the greater number) are only visible by the aid of the telescope. There are about 5000 stars visible to the naked eye. But fourteen stars of the first magnitude are in our hemisphere of the heavens, and about fifty of the second, but the number of stars of each magnitude increases prodigiously in the higher numbers, so that those stars capable only of being seen by the aid of powerful telescopes, amount to many millions; these are chiefly situated in a great belt which encircles the heavens, called the "Milky Way," which is caused by the line of vision passing through the breadth of our starry system, and consequently meeting with a greater number of stars than in other directions, where it only crosses its thickness. The other systems of stars, called "nebulæ," from their resemblance to little clouds, were supposed to consist of luminous matter of but little density, and which might at some future period be condensed into stars; but the improved power and construction of telescopes have enabled astronomers to resolve many of these nebulæ into clusters of stars, and there is but little doubt that all could be thus resolved, were the telescope of sufficient power; and thus it appears that in the infinity of space collections of systems are placed, each one too distant from the others to be calculated or written in numbers, but each consisting of thousands of suns many hundred times greater than this earth, and many millions of miles from each other. What an idea of space does this afford, and how soon do all our narrow notions of possibility and impossibility vanish before such facts accomplished by the hands of God! [Illustration: FIG. 24.] [Illustration: FIG. 25.]