Myths and Marvels of Astronomy Part 8

Some among these telescopes were not only of great power, but employed by observers of the utmost skill. The elder Herschel had for a quarter of a century studied Saturn with his great reflectors eighteen inches in aperture, and had at times turned on the planet his monstrous (though not mighty) four-feet mirror. Schroter had examined the dark s.p.a.ce within the inner bright ring for the special purpose of determining whether the ring-system is really disconnected from the globe. He had used a mirror nineteen inches in aperture, and he had observed that the dark s.p.a.ce seen on either side of Saturn inside the ring-system not only appeared dark, but actually darker than the surrounding sky. This was presumably (though not quite certainly) an effect of contrast only, the dark s.p.a.ce being bounded all round by bright surfaces. If real, the phenomenon signified that whereas the s.p.a.ce outside the ring, where the satellites of the planet travel, was occupied by some sort of cosmical dust, the s.p.a.ce within the ring-system was, as it were, swept and garnished, as though all the scattered matter which might otherwise have occupied that region had been either attracted to the body of the planet or to the rings.[36] But manifestly the observation was entirely inconsistent with the supposition that there existed in Schroter's time a dark or dusky ring within the bright system. Again, the elder Struve made the most careful measurement of the whole of the ring-system in 1826, when the system was as well placed for observation as in 1856 (or, in other words, as well placed as it can possibly be); but though he used a telescope nine inches and a half in aperture, and though his attention was specially attracted to the inner edge of the inner bright ring (_which seemed to him indistinct_), he did not detect the dark ring. Yet we have seen that in 1851, under much less favourable conditions, a less practised observer, using a telescope of less aperture, found that the dark ring could not be overlooked for an instant. It is manifest that all these considerations point to the conclusion that the dark ring is a new formation, or, at the least, that it has changed notably in condition during the present century.

I have hitherto only considered the appearance of the dusky ring as seen on either side of the planet's globe within the bright rings. The most remarkable feature of the appendage remains still to be mentioned--the fact, namely, that the bright body of the planet can be seen through this dusky ring. Where the dark ring crosses the planet, it appears as a rather dark belt, which might readily be mistaken for a belt upon the planet's surface; for the outline of the planet can be seen through the ring as through a film of smoke or a c.r.a.pe veil.

Now it is worthy of notice that whereas the dark ring was not detected outside the planet's body until 1838, nor generally recognised by astronomers until 1850, the dark belt across the planet, really caused by the dusky ring, was observed more than a century earlier. In 1715 the younger Ca.s.sini saw it, and perceived that it was not curved enough for a belt really belonging to the planet. Hadley again observed that the belt attended the ring as this opened out and closed, or, in other words, that the dark belt belonged to the ring, not to the body of the planet. And in many pictures of Saturn's system a dark band is shown along the inner edge of the inner bright ring where it crosses the body of the planet. It seems to me that we have here a most important piece of evidence respecting the rings. It is clear that the inner part of the inner bright ring has for more than a century and a half (how much more we do not know) been partially transparent, and it is probable that within its inner edge there has been all the time a ring of matter; but this ring has only within the last half-century gathered consistency enough to be discernible. It is manifest that the existence of the dark belt shown in the older pictures would have led directly to the detection of the dark ring, had not this appendage been exceedingly faint. Thus, while the observation of the dark belt across the planet's face proves the dusky ring to have existed in some form long before it was perceived, the same fact only helps to render us certain that the dark ring has changed notably in condition during the present century.

The discovery of this singular appendage, an object unique in the solar system, naturally attracted fresh attention to the question of the stability of the rings. The idea was thrown out by the elder Bond that the new ring may be fluid, or even that the whole ring-system may be fluid, and the dark ring simply thinner than the rest. It was thought possible that the ring-system is of the nature of a vast ocean, whose waves are steadily advancing upon the planet's globe. The mathematical investigation of the subject was also resumed by Professor Benjamin Pierce, of Harvard, and it was satisfactorily demonstrated that the stability of a system of actual rings of solid matter required so nice an adjustment of so many narrow rings as to render the system far more complex than even Laplace had supposed. 'A stable formation can,' he said, 'be nothing other than a very great number of separate narrow rigid rings, each revolving with its proper relative velocity.' As was well remarked by the late Professor Nichol, 'If this arrangement or anything like it were real, how many new conditions of instability do we introduce. Observation tells us that the division between such rings must be extremely narrow, so that the slightest disturbance by external or internal causes would cause one ring to impinge upon another; and we should thus have the seed of perpetual catastrophes.' Nor would such a const.i.tution protect the system against dissolution. 'There is no escape from the difficulties, therefore, but through the final rejection of the idea that Saturn's rings are rigid or in any sense a solid formation.'

The idea that the ring-system may be fluid came naturally next under mathematical scrutiny. Strangely enough, the physical objections to the theory of fluidity appear to have been entirely overlooked. Before we could accept such a theory, we must admit the existence of elements differing entirely from those with which we are familiar. No fluid known to us could retain the form of the rings of Saturn under the conditions to which they are exposed. But the mathematical examination of the subject disposed so thoroughly of the theory that the rings can consist of continuous fluid ma.s.ses, that we need not now discuss the physical objections to the theory.

There remains only the theory that the Saturnian ring-system consists of discrete ma.s.ses a.n.a.logous to the streams of meteors known to exist in great numbers within the solar system. The ma.s.ses may be solid or fluid, may be strewn in relatively vacant s.p.a.ce, or may be surrounded by vaporous envelopes; but that they are discrete, each free to travel on its own course, seemed as completely demonstrated by Pierce's calculations as anything not actually admitting of direct observation could possibly be. The matter was placed beyond dispute by the independent a.n.a.lysis to which Clerk Maxwell subjected the mathematical problem. It had been selected in 1855 as the subject for the Adams Prize Essay at Cambridge, and Clerk Maxwell's essay, which obtained the prize, showed conclusively that only a system of many small bodies, each free to travel upon its course under the varying attractions to which it was subjected by Saturn itself, and by the Saturnian satellites, could possibly continue to girdle a planet as the rings of Saturn girdle him.

It is clear that all the peculiarities. .h.i.therto observed in the Saturnian ring-system are explicable so soon as we regard that system as made up of mult.i.tudes of small bodies. Varieties of brightness simply indicate various degrees of condensation of these small satellites. Thus the outer ring had long been observed to be less bright than the inner.

Of course it did not seem impossible that the outer ring might be made of different materials; yet there was something bizarre in the supposition that two rings forming the same system were thus different in substance. It would not have been at all noteworthy if different parts of the same ring differed in luminosity--in fact, it was much more remarkable that each zone of the system seemed uniformly bright all round. But that one zone should be of one tint, another of an entirely different tint, was a strange circ.u.mstance so long as the only available interpretation seemed to be that one zone was made (throughout) of one substance, the other of another. If this was strange when the difference between the inner and outer bright rings was alone considered, how much stranger did it seem when the mult.i.tudinous divisions in the rings were taken into account! Why should the ring-system, 30,000 miles in width, be thus divided into zones of different material? An arrangement so artificial is quite unlike all that is elsewhere seen among the subjects of the astronomer's researches. But when the rings are regarded as made up of mult.i.tudes of small bodies, we can quite readily understand how the nearly circular movements of all of these, at different rates, should result in the formation of rings of aggregation and rings of segregation, appearing at the earth's distance as bright rings and faint rings. The dark ring clearly corresponds in appearance with a ring of thinly scattered satellites. Indeed, it seems impossible otherwise to account for the appearance of a dusky belt across the globe of the planet where the dark ring crosses the disc. If the material of the dark ring were some partly transparent solid or fluid substance, the light of the planet received through the dark ring added to the light reflected by the dark ring itself, would be so nearly equivalent to the light received from the rest of the planet's disc, that either no dark belt would be seen, or the darkening would be barely discernible. In some positions a bright belt would be seen, not a dark one. But a ring of scattered satellites would cast as its shadow a mult.i.tude of black spots, which would give to the belt in shadow a dark grey aspect. A considerable proportion of these spots would be hidden by the satellites forming the dark ring, and in every case where a spot was wholly or partially hidden by a satellite, the effect (at our distant station where the separate satellites of the dark ring are not discernible) would simply be to reduce _pro tanto_ the darkness of the grey belt of shadow. But certainly more than half the shadows of the satellites would remain in sight; for the darkness of the ring at the time of its discovery showed that the satellites were very spa.r.s.ely strewn. And these shadows would be sufficient to give to the belt a dusky hue, such as it presented when first discovered.[37]

The observations which have recently been made by Mr. Trouvelot indicate changes in the ring-system, and especially in the dark ring, which place every other theory save that to which we have thus been led entirely out of the question. It should be noted that Mr. Trouvelot has employed telescopes of unquestionable excellence and varying in aperture from six inches to twenty-six inches, the latter aperture being that of the great telescope of the Washington Observatory (the largest refractor in the world).

He has noted in the first place that the interior edge of the outer bright ring, which marks the outer limit of the great division, is irregular, but whether the irregularity is permanent or not he does not know. The great division itself is found not to be actually black, but, as was long since noted by Captain Jacob, of the Madras Observatory, a very dark brown, as though a few scattered satellites travelled along this relatively vacant zone of the system. Mr. Trouvelot has further noticed that the shadow of the planet upon the rings, and especially upon the outer ring, changes continually in shape, a circ.u.mstance which he attributes to irregularities in the surface of the rings. For my own part, I should be disposed to attribute these changes in the shape of the planet's shadow (noted by other observers also) to rapid changes in the deep cloud-laden atmosphere of the planet. Pa.s.sing on, however, to less doubtful observations, we find that the whole system of rings has presented a clouded and spotted aspect during the last four years. Mr.

Trouvelot specially describes this appearance as observed on the parts of the ring outside the disc, called by astronomers the _ansae_ (because of their resemblance to handles), and it would seem, therefore, that the spotted and cloudy portions are seen only where the background on which the rings are projected is black. This circ.u.mstance clearly suggests that the darkness of these parts is due to the background, or, in other words, that the sky is in reality seen through those parts of the ring-system, just as the darkness of the slate-coloured interior ring is attributed, on the satellite theory, to the background of sky visible through the scattered flight of satellites forming the dark ring. The matter composing the dark ring has been observed by Mr. Trouvelot to be gathered in places into compact ma.s.ses, which prevent the light of the planet from being seen through those portions of the dark ring where the matter is thus ma.s.sed together. It is clear that such peculiarities could not possibly present themselves in the case of a continuous solid or fluid ring-system, whereas they would naturally occur in a ring formed of mult.i.tudes of minute bodies travelling freely around the planet.

The point next to be mentioned is still more decisive. When the dark ring was carefully examined with powerful telescopes during the ten years following its discovery by Bond, at which time it was most favourably placed for observation, it was observed that the outline of the planet could be seen across the entire breadth of the dark ring. All the observations agreed in this respect. It was, indeed, noticed by Dawes that outside the planet's disc the dark ring showed varieties of tint, its inner half being darker than its outer portion. La.s.sell, observing the planet under most favourable conditions with his two-feet mirror at Malta, could not perceive these varieties of tint, which therefore we may judge to have been either not permanent or very slightly marked. But, as I have said, all observers agreed that the outline of the planet could be seen athwart the entire width of the dark ring. Mr. Trouvelot, however, has found that during the last four years the planet has not been visible through the whole width of the dark ring, but only through the inner half of the ring's breadth. It appears, then, that either the inner portion is getting continually thinner and thinner--that is, the satellites composing it are becoming continually more spa.r.s.ely strewn--or that the outer portion is becoming more compact, doubtless by receiving stray satellites from the interior of the inner bright ring.

It is clear that in Saturn's ring-system, if not in the planet itself, mighty changes are still taking place. It may be that the rings are being so fashioned under the forces to which they are subjected as to be on their way to becoming changed into separate satellites, inner members of that system which at present consists of eight secondary planets.

But, whatever may be the end towards which these changes are tending, we see processes of evolution taking place which may be regarded as typifying the more extensive and probably more energetic processes whereby the solar system itself reached its present condition. I ventured more than ten years ago, in the preface to my treatise upon the planet Saturn, to suggest the possibility 'that in the variations perceptibly proceeding in the Saturnian ring-system a key may one day be found to the law of development under which the solar system has reached its present condition.' This suggestion seems to me strikingly confirmed by the recent discoveries. The planet Saturn and its appendages, always interesting to astronomers, are found more than ever worthy of close investigation and scrutiny. We may here, as it were, seize nature in the act, and trace out the actual progress of developments which at present are matters rather of theory than of observation.

VIII.

_COMETS AS PORTENTS_

The blazing star, Threat'ning the world with famine, plague, and war; To princes death; to kingdoms many curses; To all estates inevitable losses; To herdsmen rot; to ploughmen hapless seasons; To sailors storms; to cities civil treasons.

Although comets are no longer regarded with superst.i.tious awe as in old times, mystery still clings to them. Astronomers can tell what path a comet is travelling upon, and say whence it has come and whither it will go, can even in many cases predict the periodic returns of a comet, can a.n.a.lyse the substance of these strange wanderers, and have recently discovered a singular bond of relationship between comets and those other strange visitants from the celestial depths, the shooting stars.

But astronomy has. .h.i.therto proved unable to determine the origin of comets, the part they perform in the economy of the universe, their real structure, the causes of the marvellous changes of shape which they undergo as they approach the sun, rush round him, and then retreat. As Sir John Herschel has remarked: 'No one, hitherto, has been able to a.s.sign any single point in which we should be a bit better or worse off, materially speaking, if there were no such thing as a comet. Persons, even thinking persons, have busied themselves with conjectures; such as that they may serve for fuel for the sun (into which, however, they never fall), or that they may cause warm summers, which is a mere fancy, or that they may give rise to epidemics, or potato-blights, and so forth.' And though, as he justly says, 'this is all wild talking,' yet it will probably continue until astronomers have been able to master the problems respecting comets which hitherto have foiled their best efforts. The unexplained has ever been and will ever be marvellous to the general mind. Just as unexplored regions of the earth have been tenanted in imagination by

anthropophagi and men whose heads Do grow beneath their shoulders,

so do wondrous possibilities exist in the unknown and the ill-understood phenomena of nature.

In old times, when the appearance and movements of comets were supposed to be altogether uncontrolled by physical laws, it was natural that comets should be regarded as signs from heaven, tokens of Divine wrath towards some, and of the interposition of Divine providence in favour of others. As Seneca well remarked: 'There is no man so dull, so obtuse, so turned to earthly things, who does not direct all the powers of his mind towards things Divine when some novel phenomenon appears in the heavens.

While all follows its usual course up yonder, familiarity robs the spectacle of its grandeur. For so is man made. However wonderful may be what he sees day after day, he looks on it with indifference; while matters of very little importance attract and interest him if they depart from the accustomed order. The host of heavenly constellations beneath the vault of heaven, whose beauty they adorn, attract no attention; but if any unusual appearance be noticed among them, at once all eyes are turned heavenwards. The sun is only looked on with interest when he is undergoing eclipse. Men observe the moon only under like conditions.... So thoroughly is it a part of our nature to admire the new rather than the great. The same is true of comets. When one of these fiery bodies of unusual form appears, every one is eager to know what it means; men forget other objects to inquire about the new arrival; they know not whether to wonder or to tremble; for many spread fear on all sides, drawing from the phenomenon most grave prognostics.'

There is no direct reference to comets in the Bible, either in the Old Testament or the New. It is possible that some of the signs from heaven recorded in the Bible pages were either comets or meteors, and that even where in some places an angel or messenger from G.o.d is said to have appeared and delivered a message, what really happened was that some remarkable phenomenon in the heavens was interpreted in a particular manner by the priests, and the interpretation afterwards described as the message of an angel. The image of the 'flaming sword which turned every way' may have been derived from a comet; but we can form no safe conclusion about this, any more than we can upon the question whether the 'horror of great darkness' which fell upon Abraham (Genesis xv. 12) when the sun was going down, was caused by an eclipse;[38] or whether the going back of the shadow upon the dial of Ahaz was caused by a mock sun. The star seen by the wise men from the east may have been a comet, since the word translated 'star' signifies any bright object seen in the heavens, and is in fact the same word which Homer, in a pa.s.sage frequently referred to, uses to signify either a comet or a meteor. The way in which it appeared to go before them, when (directed by Herod, be it noticed) they went to Bethlehem, almost due south of Jerusalem, would correspond to a meridian culmination low down--for the star had manifestly not been visible in the earlier evening, since we are told that they rejoiced when they saw the star again. It was probably a comet travelling southwards; and, as the wise men had travelled from the east, it had very likely been first seen in the west as an evening star, wherefore its course was retrograde--that is, supposing it _was_ a comet.[39] It may possibly have been an apparition of Halley's comet, following a course somewhat similar to that which it followed in the year 1835, when the perihelion pa.s.sage was made on November 15, and the comet running southwards disappeared from northern astronomers, though in January it was '_received_' by Sir J. Herschel, to use his own expression, 'in the southern hemisphere.' There was an apparition of Halley's comet in the year 66, or seventy years after the Nativity; and the period of the comet varies, according to the perturbing influences affecting the comet's motion, from sixty-nine to eighty years.

Homer does not, to the best of my recollection, refer anywhere directly to comets. Pope, indeed, who made very free with Homer's references to the heavenly bodies,[40] introduces a comet--and a red one, too!--into the simile of the heavenly portent in Book IV.:--

As the red comet from Saturnius sent To fright the nations with a dire portent (A fatal sign to armies in the plain, Or trembling sailors on the wintry main), With sweeping glories glides along in air, And shakes the sparkles from its blazing hair: Between two armies thus, in open sight, Shot the bright G.o.ddess in a trail of light.

But Homer says nothing of this comet. If Homer had introduced a comet, we may be sure it would not have shaken sparkles from its blazing tail.

Homer said simply that 'Pallas rushed from the peaks of heaven, like the bright star sent by the son of crafty-counselled Kronus (as a sign either to sailors, or the broad array of the nations), from which many sparks proceed.' Strangely enough, Pingre and Lalande, the former noted for his researches into ancient comets, the latter a skilful astronomer, agree in considering that Homer really referred to a comet, and they even regard this comet as an apparition of the comet of 1680. They cite in support of this opinion the portent which followed the prayer of Anchises, 'aeneid,' Book II. 692, etc.: 'Scarce had the old man ceased from praying, when a peal of thunder was heard on the left, and a star, gliding from the heavens amid the darkness, rushed through s.p.a.ce followed by a long train of light; we saw the star,' says aeneas, 'suspended for a moment above the roof, brighten our home with its fires, then, tracing out a brilliant course, disappear in the forests of Ida; then a long train of flame illuminated us, and the place around reeked with the smell of sulphur. Overcome by these startling portents, my father arose, invoked the G.o.ds, and worshipped the holy star.' It is impossible to recognise here the description of a comet. The noise, the trail of light, the visible motion, the smell of sulphur, all correspond with the fall of a meteorite close by; and doubtless Virgil simply introduced into the narrative the circ.u.mstances of some such phenomenon which had been witnessed in his own time. To base on such a point the theory that the comet of 1680 was visible at the time of the fall of Troy, the date of which is unknown, is venturesome in the extreme. True, the period calculated for the comet of 1680, when Pingre and Lalande agreed in this unhappy guess, was 575 years; and if we multiply this period by five we obtain 2875 years, taking 1680 from which leaves 1195 years B.C., near enough to the supposed date of the capture of Troy.

Unfortunately, Encke (the eminent astronomer to whom we owe that determination of the sun's distance which for nearly half a century held its place in our books, but has within the last twenty years been replaced by a distance three millions of miles less) went over afresh the calculations of the motions of that famous comet, and found that, instead of 575 years, the most probable period is about 8814 years. The difference amounts only to 8239 years; but even this small difference rather impairs the theory of Lalande and Pingre.[41]

Three hundred and seventy-one years before the Christian era, a comet appeared which Aristotle (who was a boy at the time) has described.

Diodorus Siculus writes thus respecting it: 'In the first year of the 102d Olympiad, Alcisthenes being Archon of Athens, several prodigies announced the approaching humiliation of the Lacedaemonians; a blazing torch of extraordinary size, which was compared to a flaming beam, was seen during several nights.' Guillemin, from whose interesting work on Comets I have translated the above pa.s.sage, remarks that this same comet was regarded by the ancients as having not merely presaged but produced the earthquakes which caused the towns of Helice and Bura to be submerged. This was clearly in the thoughts of Seneca when he said of this comet that as soon as it appeared it brought about the submergence of Bura and Helice.

In those times, however, comets were not regarded solely as signs of disaster. As the misfortunes of one nation were commonly held to be of advantage to other nations, so the same comet might be regarded very differently by different nations or different rulers. Thus the comet of the year 344 B.C. was regarded by Timoleon of Corinth as presaging the success of his expedition against Corinth. 'The G.o.ds announced,' said Diodorus Siculus, 'by a remarkable portent, his success and future greatness; a blazing torch appeared in the heavens at night, and went before the fleet of Timoleon until he arrived in Sicily.' The comets of the years 134 B.C. and 118 B.C. were not regarded as portents of death, but as signalising, the former the birth, the latter the accession, of Mithridates. The comet of 43 B.C. was held by some to be the soul of Julius Caesar on its way to the abode of the G.o.ds. Bodin, a French lawyer of the sixteenth century, regarded this as the usual significance of comets. He was, indeed, sufficiently modest to attribute the opinion to Democritus, but the whole credit of the discovery belonged to himself.

He maintained that comets only indicate approaching misfortunes because they are the spirits or souls of ill.u.s.trious men, who for many years have acted the part of guardian angels, and, being at last ready to die, celebrate their last triumph by voyaging to the firmament as flaming stars. 'Naturally,' he says, 'the appearance of a comet is followed by plague, pestilence, and civil war; for the nations are deprived of the guidance of their worthy rulers, who, while they were alive, gave all their efforts to prevent intestine disorders.' Pingre comments justly on this, saying that 'it must be cla.s.sed among base and shameful flatteries, not among philosophic opinions.'

Usually, however, it must be admitted that the ancients, like the men of the Middle Ages, regarded comets as harbingers of evil. 'A fearful star is the comet,' says Pliny, 'and not easily appeased, as appeared in the late civil troubles when Octavius was consul; a second time by the intestine war of Pompey and Caesar; and, in our own time, when, Claudius Caesar having been poisoned, the empire was left to Domitian, in whose reign there appeared a blazing comet.' Lucan tells us of the second event here referred to, that during the war 'the darkest nights were lit up by unknown stars' (a rather singular way of saying that there were no dark nights); 'the heavens appeared on fire, flaming torches traversed in all directions the depths of s.p.a.ce; a comet, that fearful star which overthrows the powers of the earth, showed its horrid hair.' Seneca also expressed the opinion that some comets portend mischief: 'Some comets,'

he said, 'are very cruel and portend the worst misfortunes; they bring with them and leave behind them the seeds of blood and slaughter.'

It was held, indeed, by many in those times a subject for reproach that some were too hard of heart to believe when these signs were sent. It was a point of religious faith that 'G.o.d worketh' these 'signs and wonders in heaven.' When troubles were about to befall men, 'nation rising against nation, and kingdom against kingdom, with great earthquakes in divers places, and famines, and pestilences, and fearful sights,' then 'great signs shall there be from heaven.' Says Josephus, commenting on the obstinacy of the Jews in such matters, 'when they were at any time premonished from the lips of truth itself, by prodigies and other premonitory signs of their approaching ruin, they had neither eyes nor ears nor understanding to make a right use of them, but pa.s.sed them over without heeding or so much as thinking of them; as, for example, what shall we say of the comet in the form of a sword that hung over Jerusalem for a whole year together?' This was probably the comet described by Dion Ca.s.sius (_Hist. Roman._ lxv. 8) as having been visible between the months of April and December in the year 69 A.D. This or the comet of 66 A.D. might have been Halley's comet. The account of Josephus as to the time during which it was visible would not apply to Halley's, or, indeed, to any known comet whatever; doubtless he exaggerated. He says: 'The comet was of the kind called _Xiphias_, because their tail resembles the blade of a sword,' and this would apply fairly well to Halley's comet as seen in 1682, 1759, and 1835; though it is to be remembered that comets vary very much even at successive apparitions, and it would be quite unsafe to judge from the appearance of a comet seen eighteen centuries ago that it either was or was not the same as some comet now known to be periodic.

The comet of 79 A.D. is interesting as having given rise to a happy retort from Vespasian, whose death the comet was held to portend. Seeing some of his courtiers whispering about the comet, 'That hairy star,' he said, 'does not portend evil to me. It menaces rather the king of the Parthians. He is a hairy man, but I am bald.'

Anna Comnena goes even beyond Josephus. He only rebuked other men for not believing so strongly as he did himself in the significance of comets--a rebuke little needed, indeed, if we can judge from what history tells us of the terrors excited by comets. But the judicious daughter of Alexius was good enough to approve of the wisdom which provided these portents. Speaking of a remarkable comet which appeared before the irruption of the Gauls into the Roman empire, she says: 'This happened by the usual administration of Providence in such cases; for it is not fit that so great and strange an alteration of things as was brought to pa.s.s by that irruption of theirs should be without some previous denunciation and admonishment from heaven.'

Socrates, the historian (b. 6, c. 6), says that when Gainas besieged Constantinople, 'so great was the danger which hung over the city, that it was presignified and portended by a huge blazing comet which reached from heaven to the earth, the like whereof no man had ever seen before.'

And Cedrenus, in his 'Compendium of History,' states that a comet appeared before the death of Johannes Tzimicas, the emperor of the East, which foreshadowed not alone his death, but the great calamities which were to befall the Roman empire by reason of their civil wars. In like manner, the comet of 451 announced the death of Attila, that of 455 the death of Valentinian. The death of Merovingius was announced by the comet of 577, of Chilperic by that of 584, of the Emperor Maurice by that of 602, of Mahomet by that of 632, of Louis the Debonair by that of 837, and of the Emperor Louis II. by that of 875. Nay, so confidently did men believe that comets indicated the approaching death of great men, that they did not believe a very great man _could_ die without a comet. So they inferred that the death of a very great man indicated the arrival of a comet; and if the comet chanced not to be visible, so much the worse--not for the theory, but--for the comet. 'A comet of this kind,' says Pingre, 'was that of the year 814, presaging the death of Charlemagne.' So Guillemin quotes Pingre; but he should rather have said, such was the comet whose arrival was announced by Charlemagne's death--and in no other way, for it was not seen by mortal man.

The reader who chances to be strong as to his dates may have observed that some of the dates above mentioned for comets do not accord exactly with the dates of the events a.s.sociated with those comets. Thus Louis the Debonair did not die in 837, but in 840. This, however, is a matter of very little importance. If some men, after their comet has called for them, are 'an unconscionable time in dying,' as Charles II. said of himself, it surely must not be considered the fault of the comet. Louis himself regarded the comet of 837 as his death-warrant; the astrologers admitted as much: what more could be desired? The account of the matter given in a chronicle of the time, by a writer who called himself 'The Astronomer,' is curious enough: 'During the holy season of Easter, a phenomenon, ever fatal and of gloomy foreboding, appeared in the heavens. As soon as the emperor, who paid attention to such phenomena, received the first announcement of it, he gave himself no rest until he had called a certain learned man and myself before him. As soon as I arrived, he anxiously asked me what I thought of such a sign. I asked time of him, in order to consider the aspect of the stars, and to discover the truth by their means, promising to acquaint him on the morrow; but the emperor, persuaded that I wished to gain time, which was true, in order not to be obliged to announce anything fatal to him, said to me: "Go on the terrace of the palace, and return at once to tell me what you have seen, for I did not see this star last evening, and you did not point it out to me; but I know that it is a comet; tell me what you think it announces to me." Then, scarcely allowing me time to say a word, he added: "There is still another thing you keep back: it is that a change of reign and the death of a prince are announced by this sign."

And as I advanced the testimony of the prophet, who said: "Fear not the signs of the heavens as the nations fear them," the prince, with his grand nature and the wisdom which never forsook him, said: "We must only fear Him who has created both us and this star. But, as this phenomenon may refer to us, let us acknowledge it as a warning from heaven."'

Accordingly, Louis himself and all his court fasted and prayed, and he built churches and monasteries. But all was of no avail. In little more than three years he died; showing, as the historian Raoul Glaber remarked, that 'these phenomena of the universe are never presented to man without surely announcing some wonderful and terrible event.' With a range of three years in advance, and so many kings and princes as there were about in those days, and are still, it would be rather difficult for a comet to appear without announcing some such wonderful and terrible event as a royal death.

The year 1000 A.D. was by all but common consent regarded as the date a.s.signed for the end of the world. For a thousand years Satan had been chained, and now he was to be loosened for a while. So that when a comet made its appearance, and, terrible to relate, continued visible for nine days, the phenomenon was regarded as something more than a nine days'

wonder. Besides the comet, a very wonderful meteor was seen. 'The heavens opened, and a kind of flaming torch fell upon the earth, leaving behind a long track of light like the path of a flash of lightning. Its brightness was so great that it frightened not only those who were in the fields, but even those who were in their houses. As this opening in the sky slowly closed men saw with horror the figure of a dragon, whose feet were blue, and whose head' [like that of d.i.c.kens's dwarf] 'seemed to grow larger and larger.' A picture of this dreadful meteor accompanies the account given by the old chronicler. For fear the exact likeness of the dragon might not be recognised (and, indeed, to see it one must 'make believe a good deal'), there is placed beside it a picture of a dragon to correspond, which picture is in turn labelled 'Serpens c.u.m ceruleis pedibus.' It was considered very wicked in the year 1000 to doubt that the end of all things was at hand. But somehow the world escaped that time.

In the year 1066 Halley's comet appeared to announce to the Saxons the approaching conquest of England by William the Norman. A contemporary poet made a singular remark, which may have some profound poetical meaning, but certainly seems a little indistinct on the surface. He said that 'the comet had been more favourable to William than nature had been to Caesar; the latter had no hair, but William had received some from the comet.' This is the only instance, so far as I know, in which a comet has been regarded as a perruquier. A monk of Malmesbury spoke more to the purpose, according to then received ideas, in thus apostrophising the comet: 'Here art thou again, cause of tears to many mothers! It is long since I saw thee last, but I see thee now more terrible than ever; thou threatenest my country with complete ruin.'

Halley's comet, with its inconveniently short period of about seventy-seven years, has repeatedly troubled the nations and been regarded as a sign sent from Heaven:

Ten million cubic miles of head, Ten billion leagues of tail,

all provided for the sole purpose of warning one petty race of earth-folks against the evils likely to be brought against them by another. This comet has appeared twenty-four times since the date of its first recorded appearance, which some consider to have been 12 B.C., and others refer to a few years later. It may be interesting to quote here Babinet's description of the effects ascribed in 1455 to this comet, often the terror of nations, but the triumph of mathematicians, as the first whose motions were brought into recognisable obedience to the laws of gravity.[42]

'The Mussulmans, with Mahomet II. at their head, were besieging Belgrade, which was defended by Huniade, surnamed the Exterminator of the Turks. Halley's comet appeared and the two armies were seized with equal fear. Pope Calixtus III., himself seized by the general terror, ordered public prayers and timidly anathematised the comet and the enemies of Christianity. He established the prayer called the noon _Angelus_, the use of which is continued in all Catholic churches. The Franciscans (_Freres Mineurs_) brought 40,000 defenders to Belgrade, besieged by the conqueror of Constantinople, the destroyer of the Eastern Empire. At last the battle began; it continued two days without ceasing. A contest of two days caused 40,000 combatants to bite the dust. The Franciscans, unarmed, crucifix in hand, were in the front rank, invoking the papal exorcism against the comet, and turning upon the enemy that heavenly wrath of which none in those times dared doubt.'

The great comet of 1556 has been regarded as the occasion of the Emperor Charles V.'s abdication of the imperial throne; a circ.u.mstance which seems rendered a little doubtful by the fact that he had already abdicated when the comet appeared--a mere detail, perhaps, but suggesting the possibility that cause and effect may have been interchanged by mistake, and that it was Charles's abdication which occasioned the appearance of the comet. According to Gemma's account the comet was conspicuous rather from its great light than from the length of its tail or the strangeness of its appearance. 'Its head equalled Jupiter in brightness, and was equal in diameter to nearly half the apparent diameter of the moon.' It appeared about the end of February, and in March presented a terrible appearance, according to Ripamonte.

'Terrific indeed,' says Sir J. Herschel, 'it might well have been to the mind of a prince prepared by the most abject superst.i.tion to receive its appearance as a warning of approaching death, and as specially sent, whether in anger or in mercy, to detach his thoughts from earthly things, and fix them on his eternal interests. Such was its effect on the Emperor Charles V., whose abdication is distinctly ascribed by many historians to this cause, and whose words on the occasion of his first beholding it have even been recorded--

"His ergo indiciis me mea fata vocant"--

the language and the metrical form of which exclamation afford no ground for disputing its authenticity, when the habits and education of those times are fairly considered.' It is quite likely that, having already abdicated the throne, Charles regarded the comet as signalling his retirement from power--an event which he doubtless considered a great deal too important to be left without some celestial record. But the words attributed to him are in all probability apocryphal.

The comet of 1577 was remarkable for the strangeness of its aspect, which in some respects resembled that of the comet of 1858, called Donati's. It required only the terror with which such portentous objects were witnessed in the Middle Ages to transform the various streamers, curved and straight, extending from such an object, into swords and spears, and other signs of war and trouble. Doubtless, we owe to the fears of the Middle Ages the strange pictures claiming to present the actual aspect of some of the larger comets. Halley's comet did not escape. It was compared to a straight sword at one visit, to a curved scimitar in 1456, and even at its last return in 1835 there were some who recognised in the comet a resemblance to a misty head. Other comets have been compared to swords of fire, b.l.o.o.d.y crosses, flaming daggers, spears, serpents, fiery dragons, fish, and so forth. But in this respect no comet would seem to have been comparable with that of 1528, of which Andrew Pare writes as follows: 'This comet was so horrible and dreadful, and engendered such terror in the minds of men, that they died, some from fear alone, others from illness engendered by fear. It was of immense length and blood-red colour; at its head was seen the figure of a curved arm, holding a large sword in the hand as if preparing to strike. At the point of this sword were three stars; and on either side a number of axes, knives, and swords covered with blood, amongst which were many hideous human faces with bristling beards and hair.'

Such peculiarities of shape, and also those affecting the position and movements of comets, were held to be full of meaning. As Bayle pointed out in his 'Thoughts about the Comet of 1680,' these fancies are of great antiquity. Pliny tells us that in his time astrologers claimed to interpret the meaning of a comet's position and appearance, and that also of the direction towards which its rays pointed. They could, moreover, explain the effects produced by the fixed stars whose rays were conjoined with the comet's. If a comet resembles a flute, then musicians are aimed at; when comets are in the less dignified parts of the constellations, they presage evil to immodest persons; if the head of a comet forms an equilateral triangle or a square with fixed stars, then it is time for mathematicians and men of science to tremble. When they are in the sign of the Ram, they portend great wars and widespread mortality, the abas.e.m.e.nt of the great and the elevation of the small, besides fearful droughts in regions over which that sign predominates; in the Virgin, they imply many grievous ills to the female portion of the population; in the Scorpion, they portend a plague of reptiles, especially locusts; in the Fishes, they indicate great troubles from religious differences, besides war and pestilence. When, like the one described by Milton, they 'fire the length of Ophiuchus huge,' they show that there will be much mortality caused by poisoning.