"Oh! He told you so when you repeated to him all that folly which I talked about him at Camlough." An involuntary look of disgust crept for a moment into May's eyes. It did not escape Katherine, nor was she likely to forget it when it presently disappeared. "You are mistaken in me," said May; "I could not so betray any one. "Ah! that is good of you. Primness, I see, sometimes does one a service. I remember now that I made you promise to forget that conversation." "I have a better memory than you." "You have a better everything, my dear, except physique and self-will. I yield to no one in beauty, and I have a talent for having my own way, which amounts to genius. You shall see it in full working before I have been here long." May looked up brightly, and laughed at her audacity, which, she yet knew very well, was not a merry jest. After all, this was no unearthly creature of unhallowed powers not to be baffled; but only wild Katherine Archbold. It was her nature to do mischief where she could, but May had a subtle power of her own, of which she was not all unconscious. And she would not fear any other woman on earth, were that other woman incarnate beauty itself. Something of this Katherine found in the speaking dark eyes. So she became more offensive. "Are you desperately in love with your fine Paul?" she asked. "I don't dislike him," said May. "Bah!" said Katherine, provoked. "As if I did not know that you are a soft little fool, ready to love anybody!" May coloured. "Not anybody," she said; not you, for instance." "Oh, she has lost her temper at last. Not me? Well, look here. I will make a bargain with you. You begin to love me with all your might, and I will give you this pretty ring. It is worth a hundred guineas. The diamonds flashed in the light of the blazing faggots, as Katherine held the ring poised on the end of her little finger. May put her hands behind her back. "Keep it," she said; "I am too poor to give you even the wretched price you ask for it." Katherine frowned and smiled. "I always knew you were obstinate," she said, "but you are sharper than I thought you.' There was sudden silence between the two girls. It was as if both had under stood that there had been more under their words than either had cared to utter. Again the firelight played its weird pranks about the guest's golden head, and threw strange meanings into her eyes, and laid ominous touches upon her mouth. And again the superstitious, unaccountable terror of approaching harm gathered round May's heart; till a welcome household sound in the passage broke the spell, and she felt ashamed of herself. "Come!" she said, ". we are a silly pair to stay here sparring at one another. Don't you think we had better go and be sociable in the parlour? My aunt is waiting for us, and I want to present you to Mr. Finiston." "Wait!" said Katherine. She had lighted the only remaining stick of the wicked faggots. She held the blazing wood in her hand, and watched it burn away slowly towards her fingers, while a lurking smile played about the corners of her mouth. "I am reading your future. I am looking to see whether you will be married to your Paul. Did you ever hear of Margaret and her daisy? Well, if the burnt part breaks and drops away before the flame reaches my finger it is the breaking of your engagement. Watch, watch! It is gone!" The piece of red charcoal had dropped on the hearth. Katherine tossed the burning morsel that remained into the fire. The flames dropped in the grate, and the room was in darkness. "Don't be a goose!" said May, and opened the door into the lighted passage. But Katherine was not accustomed to be 1 called a goose. PERIODICAL COMETS. THE discoveries of modern science lead us to infer that there is a great resemblance, in many particulars, between the greatest and the smallest bodies in crea tion; that atoms, like suns, are separated from each other by distances which are enormous when compared with their actual size; that the molecules composing a bar of iron waltz round and round in circlets or ovals, exactly as Mars, Jupiter, and the rest of us, whirl round Phoebus, and Phoebus himself and his fellow-stars revolve round some unknown central point. Perhaps some atoms, in bodies called solid, may dance up and down, like gnats in sunshine, the swarm remaining stationary while each gnat keeps changing its place 1 in the airy reel; others may simply vibrate Atoms, too, like suns and planets, are We cannot suppose the atoms of which bodies are composed to be in actual contact, for in that case their expansion and contraction by heat and cold, and other causes, would be impossible. And yet we are unable to force them closer together than they choose to go. Water, so yielding to the touch, is very slightly compressible. Pressure has been tried in vain to permanently augment the density of soft metals. Steam, ice, gunpowder, fulminating mercury, afford familiar instances of the power of atoms. In short, the smallest molecules, like the largest stars, are separated by intervening spaces, perform their allotted motions, and are gifted with "strength enough to insure them respect. As the least and the largest bodies resemble each other, so do the lightest and the heaviest in their obedience to universal laws. Nothing, to be visible, can be conceived lighter than a comet. Had the ancients been aware of the excessive levity now attributed to them, they would have accounted for their extraordinary conduct by that cause. And yet the circumstance that stars shine through comets ought to have raised the suspicion that they could not be very dense. And yet, according to some, the moon was once a comet; Saturn also was once a comet. But the moon or Saturn, either of them, contains matter enough to make millions of comets. Had the lightness of comets been known in former days, it might have dissipated all fears of their influence in causing either political disasters or physical catastrophes. Such things of nought can neither be or more capable of kindling wars, upraising deluges, nor splitting worlds into two pieces. These remarkable bodies sometimes throw out tails one hundred millions of miles in length and fifty thousand in diameter. What, however, is the mass of matter of which such a prodigious tail consists? According to Sir John Herschel, if it were all swept together and suitably compressed, it might be carted away in a single horse-load. Can bodies so infinitely light, we feel tempted to ask, be subject to the ordinary laws of gravity? Tycho Brahé was the first, in modern times, to find that comets are not meteors engendered in the atmosphere, as held by Aristotle and numerous astronomers of later date. Kepler was of the same opinion, which he illustrated by a striking comparison, not devoid of plausibility. "Since the sea has its whales and leviathans, it is natural that the air should have its monsters and comets, shapeless bodies engendered from its superfluous dregs by a sort of animal faculty. As to their number, there are more comets in the sky than fish in the ocean." They were consequently supposed to be not far distant from the earth. But Tycho Brahé, not being able to ascertain the diurnal parallax of the comet of 1577, concluded that it must be further away from the earth than the moon. Their movements were still more puzzling. Kepler supposed that they advanced in straight lines; that is, we suppose, in curves parallel to the surface of the earth. It was a nearer guess that comets describe a parabolic orbit-if that can be called an orbit which is not an orbit (there being no return), but only a path. This parabola run through by a comet, may be compared to a huge pair of sugar-tongs, with legs of infinite or rather indefinite length, which could never meet at their tips, even to grasp and catch the sweetest, solidest, most inviting of comets. Each comet came from a sort of nowhere, and, after showing itself to the wondering earth, returned to its nowhere again, lost in the depths of the heavens, the abyss of space, beyond the limits of the known celestial regions. But unfortunately for such suppositions, there is no such place as nowhere, any more than there is such a fact or process as annihilation. There is change; which is life. A condition of material unchangeability and inaction would be absolute death; instead of which we everywhere meet with force and movement. The limbo of poets, if it have a name, has no local habitation discoverable well as its reappearance, predicted by by telescopes. There is no "behind the our illustrious countryman fifty-four years scenes" in the heavens whence new stars beforehand. So proud was the Oxford and comets may make their entrance and professor of his discovery, that he begs strut and fret their hour on the celestial posterity (now our ancestors) to remember stage; no lumber garret or property that it was due to an Englishman. room into which they can retire and be stowed out of the way. The universe is an open, infinite somewhere, at every point of its extent as much a real somewhere as it is here, where we happen for the moment to be bowling through space. A little thought will, therefore, tell us that it is just as interesting to know what becomes of comets after we lose sight of them as to watch their doings while they are visible. Tycho Brahe's observations led him to infer that the comet of 1577 had described round the sun an arc of a circle including within it the orbits of Mercury and Venus. Herelius, in spite of his erroneous notions respecting the nature of comets, first discovered that the curves in which they moved were parabolic in their nature; but he appears to have known nothing-a grand and vital omission-of the place occupied by the sun within those curves, nor of the laws which governed the velocities of those bodies as they approached the summits of their parabolas. It was an immense step when an astronomer dared predict that a given comet, which he had observed, would one day return-a still greater when he ventured to fix an epoch for its appearance when he would not himself survive to witness the fact. And our interest in the comets whose periodical return is well established increases with their increasing number. There appears no reason why this number should not augment with a rapidity comparable to the quickly successive discoveries of the telescopic planets circulating between Mars and Jupiter. At present we are acquainted with eight comets which have come back to visit us once or several times, after their return had been announced as probable in consequence of the circumstances of their previous arrivals. M. Delaunay, in the Annuaire du Bureau des Longitudes for 1872, gives sundry historical details, which we propose to abridge, relating to the discovery of the periodicity of those eight comets. The most important of these in the annals of astronomy is Halley's comet. It is the first whose periodicity was ascertained, and its period of revolution is the longest known. Very remarkable also was the clue which led to its identification, as Edmund Halley calculated the elements of his comet's orbit at its perihelium passage in 1682, when it blazed in the heavens with wonderful splendour. He found that orbit to correspond exactly with those of the comets of 1531 and 1607, which led him to conclude that all the three were one and the same individual, making, in 1682, its third public appearance on the stellar stage. These three returns of the same comet gave it a period of revolution of about seventy-five years and a half, with a variation which might amount to two years. This incertitude did not prevent Halley from predicting its return in 1758. Capini was the first to conceive the idea of searching the records of ancient observations for the orbits of comets, with a view to their possible return. If it had occurred to him to refer their motions to the sun's attraction, and to consider the sun as their centre, he would have made an enormous step in advance. He employed the most delicate processes then known to astronomy to ascertain when comets would reappear, but he had no means of verifying his predictions, because the resemblances which he thought he found in comets were only apparent. He ought to have compared their motions by referring them to the sun's influence. Halley was the first astronomer to adopt this grand principle, and he signally sueceeded in consequence. His method led to the important conclusion that comets are veritable planets. Their movements, which appear extremely irregular, are not so when referred to the sun. The difference be tween them (considered as members of the solar system) lies in the form of the orbits they describe, and which, instead of being almost round, like those of the planets, are extremely long ovals, which is the reason why we lose sight of them during such lengthened intervals of time. We have seen that there was a margin of about two years left open for the comet's return. It was an allowance made for the action of the planets on the comet's course. The exact amount of that action was diffi cult to determine. Nevertheless, Clairaut set to work to calculate it, in confirmation of his enthusiastic faith in the Newtonian system, which was not universally admitted י then by the world called "learned," as it now is. "The comet we are expecting,' he said, in the public sitting of the Académie des Sciences, on the 14th of November, 1758, "has become the object of much greater interest than the public usually bestow on astronomical questions. The true lovers of science desire its return, because the result will be a brilliant confirmation of a system (Newton's) in whose favour every phenomenon gives evidence. Those, on the contrary, who delight to see philosophers plunged in trouble and uncertainty, hope that it will not come back, and that the discoveries of Newton and his partisans will fall to the level of other hypotheses, which are the offspring of mere imagination." Undaunted by this scepticism and opposition, which we can hardly understand at the present day, he traced the constellations it would traverse, and the planets it would meet with on its way, and found that Saturn would retard its arrival by one hundred days, and Jupiter by five hundred and eighteen-in all by six hundred and eighteen; that is, this revolution of the comet would be a year and eight months longer than the previous one. In other words, its passage at its perihelium would take place about the middle of April, 1759, within a month, more or less. Never had a scientific prophecy excited greater curiosity from one end of Europe to the other. The comet did reappear; it followed the path through the constellations which Clairaut had traced for it; it reached its perihelium on the 12th of March, 1759, just a month before the date indicated. We may note that the difference between theory and observation might be caused by the action of the planets Uranus and Neptune, of which (as he did not know of their existence) Clairaut could take no account in his calculations. tonians. of the solar system of which we have been unable to take account-for the comets of whose situation and strength we are ignorant-for the resistance of the ethereal matter, which we are incompetent to appreciate, and for the numerous quantities which we are obliged to neglect in an approximative calculation? The difference of five hundred and eighty-six days between two revolutions of the same comet -a difference produced by the disturbing forces of Jupiter and Saturn-is a more striking demonstration than one could have hoped to obtain of the grand principle of universal gravity. It places the law amongst the number of fundamental physical truths, of whose reality it is no more possible to doubt than it is of the bodies which produce attraction." Halley's comet was again due in 1835. M. Damoiseau, taking into account the disturbance to be caused by Uranus, fixed its perihelic passage for the 4th of November of that year. Another astronomer, M. de Pontecoulant, predicted for the 13th (according to M. Delaunay); but M. Lecouturier states that M. de Pontecoulant's calculation gave the 15th of November, at midnight, as the date. The comet really passed the point of its orbit nearest to the sun at nine o'clock in the morning of the 16th of November, thus failing to keep the rendezvous given it by so brief a delay as nine short hours. As the anxious expectant was aware of its coming, he probably waited patiently, for astronomy can boast of but few more brilliant feats than this. According to the same gentleman's calculations, twenty-seven thousand two hundred and seventeen days must elapse between the comet's departure from its perhelion in 1835 and its next arrival at that point of its orbit; this calculation appoints the 24th of May, 1910, for that It was a grand triumph for the New- interesting phenomenon to come off. The "We have all witnessed the arithmetic which hangs about Halley's accomplishment of the event," wrote comet in groups of figures, inconceivable by Lalande, who had rendered great assist- unlearned minds, informs us that for thirtyance in the calculations; "so that it is eight years it travels in our direction from placed beyond a doubt that comets are the extreme limits of our solar system to a really planets which turn like the others point distant about forty-eight millions of round the sun. M. Clairaut demanded a miles from the sun; that it then retreats month's grace in favour of theory, and the rapidly, and thirty-eight years afterwards, month's grace has not been exceeded. The leaving Uranus behind it, reaches Nepcomet came, after a period of five hundred tune's orbit, about three thousand millions and eighty-six days longer than its pre- of miles from the sun. These figures are ceding period, that is, thirty-two days far too enormous to convey any definite before the appointed date. But what is idea of distance; but it would be easy to thirty-two days for the various attractions | calculate how many years it would take a racehorse to gallop round this course from Encke's comet, named after the calculator of its elements, completes its revolution in about three years and a half. Discovered in 1818 by M. Pons, at Marseilles, it was suspected to be identical with a comet observed in 1805, which suspicion was confirmed by Encke. Regarding merely the rapidity of its successive returns, this object might be considered a planet; but it has been left on the list of comets, both on account of the appearances it presents, and because it is not visible to us throughout the whole course of its orbit. The most noteworthy point about Encke's comet results from a comparison of the dates of its successive returns to the same point of its orbit. Making every possible allowance for the disturbing forces exercised on it by the planet's attraction, Encke found that the period of its revolution is constantly diminishing, which would indicate the presence of a resisting medium -that interstellar space is not a vacuum, but is filled with an ether possessing some density, however slight. Such a medium, by gradually checking the comet's velocity, would cause it to yield to the sun's attraction; its orbit, contracting more and more, would be run through in shorter and shorter periods of time. Encke's comet was last seen in November, 1871. time of its perihelic passage. But in 1846, astronomers, without any reproach to their sobriety, saw it double. It was two comets, travelling side by side, with a tendency rather to quit than to approach each other. The quarrel, too, had come on suddenly; shortly before its complete accomplishment, such observers as Maury, of Washington, and Challis, of Cambridge (England), declare that they saw no symptoms of the separation. The disunited couple are expected back in the autumn of 1872, and we shall be curious to see whether they have made it up, and behave as becomes their high position. After this specimen of eccentricity, the other return comets are valuable rather as increasing the list of periodicals than for any special interest they offer to the general reader. There is Faye's comet, with a period of seven years and a half, discovered at the Paris Observatory in 1843. M. le Verrier, calculating the perturbations it would experience on its way, fixed its perihelic passage for the 3rd of April, 1851, a little after midnight. The prediction, wonderfully exact, was fulfilled on the 2nd of April, about ten in the morning. The same comet was seen again in 1858 and 1865. It ought to show itself once more in 1873. Brorsen's, with a period of five years and a half, discovered at Kiel in 1846, is a more slippery comet than the preceding. It was searched for in vain in 1851, but found again in 1857. Similarly, in 1862, it was not forthcoming, but was detected again in 1868. Doubtless Astronomer Brorsen is himself more punctual than the untrustworthy vagabond who bears his name. D'Arrest's comet, discovered at Leipzig in 1851, has a period of six and a half years nearly. Its return was announced for the end of 1857; but as it would not be visible in the earth's northern hemi- i sphere, the documents, and, if we may say so, its passport, prepared by M. Yvon Villarceau, were sent to observatories in the southern hemisphere in anticipation of its arrival. The result answered the French astronomer's predictions. The comet kept its appointment within twelve hours. În 1864 it gave no sign; but in 1870, on the 31st of August, it answered to its name. Biela's comet (with a period of six years and three quarters) is another instance of fantastic resemblance between the largest and the smallest works of the Creator. There are microscopic plants and animals (examples, closterium and trichoda) which, after attaining a certain age, contract in the middle, become fiddle-shaped, hourglass-shaped, and finally separate into two independent, thrifty individuals. Microscopists call this process "fissiparous multiplication." But who would suppose that a comet would ever adopt that mode of in- On the 4th of January, 1858, Mr. Tuttle ? Nevertheless, Biela's has, beyond discovered a comet at Cambridge, United the possibility of doubt, done so. Dis-States. Tuttle's comet has a period of revolucovered in 1826, seen again in 1832, it could tion of something more than thirteen years not be observed in 1839 in consequence of and a half. It was recognised at Marseilles the unfavourable position of its orbit at the by M. Borelly, in October, 1871. Finally, crease |