"A frozen continent Lies dark and wild, beat with perpetual storms Herschel also mentions another pleasant contingency dependent on a residence on Saturn, namely the possibility of a ring giving way and burying everything below it. So much for the planets. Some of the fixed stars present as great difficulties, being liable to temporary or permanent extinction. An occurrence of this nature is said to have determined Hipparchus to draw up the first catalogue of the stars, and ever since that time, wellnigh two thousand years ago, such phenomena have been frequently noticed. A remarkable apparition of this kind happened in 1572, and was seen by that singular mortal but justly renowned astronomer, Tycho Brahe, as he was returning from his watch-tower at Knudsthorp. He would very probably not have noticed its first appearance, had not his attention been drawn by seeing a number of country people gazing at it. It was near Cassiopea and was already as bright as Sirius, though he knew it was not there half an hour before. It grew in beauty till it outshone Jupiter in his greatest splendour, and was at one time visible at mid-day. In about a month its lustre began to wane, and in about fifteen months more it had entirely disappeared. A very brilliant star of this kind was suddenly seen at Prague in the autumn of 1604; it was almost as brilliant as Venus. It gradually decayed in lustre during the next year and has never been seen since. Mr. Hind observed one which broke out into view in 1848, near the place where this star of 1604 was seen; some are also mentioned rather obscurely by the chinese. A few go on in a chronic fashion of this kind which is rather bewildering. One in Argus, for instance, after sometimes being of the first magnitude and again of the fourth, suddenly blazed out in 1838 with extraordinary brightness, and then after a rest of five years the fitful planet all at once acquired such brilliancy as almost to rival the glorious dogstar. The "lost Pleiad seen no more below," the immortal maid whose bosom owned a mortal flame, who was for that struck out of the roll of the stars and her place made a blank in the heavens, is now really in a very thriving condition. "What conclusion," says a writer quoted by Sir John Herschel, are we to draw as to the comfort or habitability of a system dependent for its supply of light and heat on so uncertain a source?" Why, a very unfavourable one I should say. A residence on a planet which is apt to become suddenly girdled about by an atmosphere in a state of intense light or electric tension, and then as suddenly to be involved. in cold and darkness, must be decidedly uncomfortable. 66 Finally we have an excellent authority for believing that since the records of astronomy began many stars have died out, a very potent argument for those who are desirous of assuring us that our earthly habitation cannot last much longer. How this extinction happens we cannot exactly understand, unless we believe that the star is shivered into atoms, or that the sun which lighted it had absolutely collapsed, for if the crust of our earth were broken up and boiling lava poured over it, if it were honeycombed with black and smoking craters till it looked like some great pottery or ironworks laid waste, if all life were destroyed by floods. of ice, it would most probably look as bright as ever to the stargazers of Venus and Mercury. Men laughed when Dr. Darwin surmised that Chaos blew up like a barrel of gunpowder and ejected the sun, on the principle perhaps that an empty house is better than a bad tenant, that the sun then blew up and ejected the earth, and so on till matters were comfortably arranged but it seems difficult to understand how the extinction of which mention has just been made could have been effected in any other way. Lagrange calculated that it was not such a difficult thing to blow up a planet as might be supposed! only requiring about twenty times the force of a cannon-ball!! so that some day or other, when we can get near enough, we shall be able to explode a planet with one of Whitworth's guns, which also in the case of any very eccentric star, may prove a cheaper plan for solving any knotty points about its orbit than paying astronomers for making calculations about the matter. The explosion theory is however really still believed in. Kirkwood has actually calculated the exact size of the parent star which was shivered into all the pretty little planets lately discovered-Juno, Pallas, and the rest. How the inhabitants of the star fared on this occasion we are left to conjecture. Besides these instances, there are stars which undergo a similar change, but occupy a very much shorter time about it, their cycle of changes being performed in days or hours instead of years. Argelander has reckoned the number of these variable stars at twenty-four, but there are several besides in which this change is not so well marked. And now, gentle reader, you have reached the end of THE STREAM OF LIFE. APPENDIX, I.-P. 5. "Faint traces of animal remains make their appearance in strata of as early a date as any in which impressions of plants have been detected."--Lyell, Principles of Geology, Fifth Edition, vol. i., p. 234. II.-P. 12. Sir Charles Lyell has expressed very strong doubts as to whether more violent disturbances occurred in very remote times than now. "There can be no doubt," he says, "that periods of disturbance and repose have followed each other in succession in every region of the globe; but it may be equally true, that the energy of subterranean movements has always been uniform as regards the whole earth." III.-P. 16. Hugh Miller, in his "Footprints of the Creator," says that vegetable remains are much more numerous in the lower than the upper old red sandstone.-P. 185. IV. P. 28. Miller, in his "Footprints of the Creator," beautifully refers to some of these scenes; 66 the land of the Wealden, with its gigantic iguanodon rustling amid its tree ferns and cycadeæ, comes next; then comes the green land of the Oolite, with its little pouched |