he lived on other men's bread, and went up and down other men's stairs. He was honoured, it is true. Great nobles were glad to employ his services, and, as we have said, the fact of his being so often selected by the rulers of Florence for condemnation, shows that at least they regarded him as a man to be reckoned with. But probably the strongest evidence of the estimation in which he was held is to be found in Villani's obituary chapter, wherein his character and accomplishments are set forth with a fulness which the historian elsewhere reserves for Popes and sovereigns; a fulness all the more noteworthy that his name never occurs in the chronicle of events in which he undoubtedly took a leading part.

When Italy and Florence had lost him beyond hope of recovery, it was realized that he was one of his country's greatest glories. Then chairs were founded from which the most eminent literary men of the age should expound his works; and commentator after commentator-nine or ten before the end of the fourteenth century-cleared up some obscurities and made others more obscure. Of course, so far as historical allusions go, the writers who were nearly or quite contemporary with the events are often of great service; but it is otherwise, as a rule, when a knowledge of books is wanted. We are never so much impressed with the vastness of Dante's reading, as when we see the utter failure of these learned men even to observe, in many cases, that any explanation or illustration of an allusion is wanted. This, however, brings us back to the point from which we started, namely that, much as has been written about Dante, the possible fields of research are by no means exhausted.

The interest of the events which moulded Dante's career and influenced his work has perhaps led to their occupying too large a share of these papers; but it has been thought best to go into the history at some length, as being after all the first and most essential step towards a thorough comprehension of the position which his writings, and especially the Commedia, hold in European literature. This is quite unique of its kind. Never before or since has a poem of the highest imagination served as a great political manifesto, and as a summary of history; and we may safely say that no such poem will in future serve those purposes, at all events until the conditions under which it was produced recur. Whether that is ever likely to be the case, those who have followed the history may judge.

ARTHUR J. BUTLER.

GREAT COMETS.

BY J. E. GORE, F.R.A.S.

THE appearance of a large and bright comet always attracts a considerable amount of public interest. The reason of this is easily understood. The aspect of a comet, especially if it has a long and bright tail, differs so remarkably from the other heavenly bodies, with which all are familar, that it at once arrests the attention of even the most casual observer of celestial phenomena. Their motion is also usually so rapid across the face of the sky, that their apparent path among the stars may generally be traced from night to night, and the comparatively short duration of their visibility to the naked eye makes them objects of unusual mystery and wonder, not only to the public, but even to the professional astronomer. Telescopic comets are comparatively numerous, but as these rarely become visible without optical aid, they are only objects of interest to advanced students and computers, and to those who possess telescopes of sufficient power to follow these faint objects among the stars which lie near their path.

Large comets are rare objects. Comparatively few bright objects of this class are recorded in the annals of astronomical history. The first account of such an apparition in the heavens dates back so far as B.C. 1770. The record handed down to us is, of course, very vague and uncertain, but the description most probably refers to a brilliant comet. St. Augustine, in his work De Civitate, quoting from Varro, says, 'There was seen a wonderful prodigy in the heavens, worthy to be compared with the brilliant star Venus, which Plautus and Homer, each in his own language, call the" evening star." Castor avers that this fine star changed colour, size, figure, and path; that it was never seen before, and has never been seen since. Adrastus of Cyzicus and Dion the Neapolitan refer the appearance of this great prodigy to the reign of Oxyges.' It is, of course, possible that the 'prodigy' may have been a 'temporary star,' like Tycho

Brahé's 'Pilgrim Star' of 1572 in Cassiopeia; but the reference to change of 'figure and path' suggests that the object was really a comet of unusual splendour.

Pingré, who has studied the subject of comets closely, thinks that an object seen, B.C. 619 or 618, was a comet, and that it is referred to by the prophet Jeremiah in the first chapter of his book. Pliny relates that at the battle of Salamis (B.C. 479) a comet was visible in the shape of a horn. Some of the ancient descriptions of comets are very curious, and frequently rather ridiculous. One (B.C. 134) is described as being brighter than the sun! A second as 'the size of a bull's eye, and the tail like that of a peacock'! While the tail of another was 'twenty feet long, and the head was the size of a wine-glass'! The Chinese annals record that the tail of the comet of 1472 was 'as long as a street'! and the comet of 1500 is said to have been 'as large as a ball.' But neither the length of the street nor the size of the ball is specified in these absurd descriptions.

Seneca describes a comet which appeared after the death of Demetrius, King of Syria, B.C. 146, which was so bright as to dissipate the darkness of the night'! He also tells us of a comet which was seen (B.C. 137) in the reign of Attalus, and which had a tail equal in length to the Milky Way! This must have been a comet of unusual size. A still more brilliant comet is said to have appeared at the birth of Mithridates (B.C. 134). It is described by Justinus as of a brilliancy 'superior to that of the sun'! This comet is also referred to in the Chinese annals. Another comet which Pliny speaks of as having been seen in B.C. 75, is described as giving as much light as the sun does when the sky is cloudy! But these accounts are most probably greatly exaggerated.

After the death of Julius Cæsar (B.C. 44) a large comet-'the star of the mightiest Julius'-became visible, which was popularly supposed to represent his soul, translated to the ranks of the gods! Shakespeare says—

'When beggars die, there are no comets seen;

The heavens themselves blaze forth the death of princes.'1

A comet which appeared in B.C. II, and hung over Rome before the death of Agrippa, is supposed to have been an apparition of Halley's comet, now a well-known member of the solar system. During the famous siege of Jerusalem by Titus, a comet is

1 Julius Cæsar, Act II. scene 2.

said by Josephus to have hung over the doomed city (A.D. 69). Its appearance is confirmed by Dion Cassius in his Roman History.' Before the death of Constantine (A.D. 337) a comet of extraordinary size is said to have been visible.

'The most terrible comet on record' is said to have appeared A.D. 400, in the form of a sword. Its tail was thirty degrees long, but as this length has often been exceeded, the word 'terrible' must refer to its shape rather than its size. A great comet was observed in Europe and China A.D. 530 or 531. It is described as 'a very large and fearful comet,' and Hind thinks that it may have been an appearance of Halley's comet, as also comets recorded in 608 and 684.

The comet of A.D. 837 must have been one of considerable size, as it had at one time a tail of eighty degrees in length, as recorded in the Chinese annals. It approached the earth. within a distance of four millions of miles. In the year 893, a comet is said to have been seen with a tail of a hundred degrees in length, which afterwards increased to two hundred degrees! As it is clearly impossible for the tail of any comet to exceed one hundred and eighty degrees in length, this account is evidently much exaggerated. A length of a hundred degrees is, however, quite possible.

In the year 945, a brilliant comet is said to have been seen while Theotilon, Bishop of Tours, was travelling. The bishop died on the journey, and the comet was so bright as to give light to the funeral party on their way to Tours, a distance of two hundred miles. It has been suggested that this was a previous appearance of Tycho Brahe's temporary star of 1572, but there seems to be little doubt that the object was really a comet. Hepidannus speaks of a comet of 'extraordinary grandeur' as being visible in the southern sky in A.D. 1012. In 1066, the year of the Norman conquest of England, there was an apparition of Halley's comet, which caused widespread terror throughout Europe. In England it was thought to herald the success of the Norman invasion. This comet is the one depicted in the Bayeaux tapestry. A splendid comet ' is recorded in the year 1106. The great comet of September, 1882, was possibly a return of this comet.*

In 1264 one of the grandest comets on record' appeared. Its tail is said to have been a hundred degrees in length, or longer than from the horizon to the zenith. It was observed English Mechanic, February 2, 1883.

*

in China and Europe, and was visible for three months. Several writers in 1402 speak of a 'prodigious' comet which was visible in the daytime! Indeed it would seem that there were two brilliant comets seen this year, both visible in daylight! The second of these was supposed to have presaged the death of John Gallius Visconti, Duke of Milan. But the birth or death of several great men were supposed to have been heralded by the appearance of a bright comet.

In the year 1456 there was another apparition of Halley's comet. It is described as of 'unheard-of magnitude,' and it had a tail over sixty degrees in length. It was referred to in a bull issued by Pope Calixtus II. Researches on the path pursued by Halley's comet in that year have shown that it was then very favourably situated with reference to the earth, and that the description of its appearance is probably not exaggerated. The great comet of 1472 made rather a near approach to the earth. When at its nearest it was only about one-thirtieth of the sun's distance from our globe, and it was then visible in full sunshine.

The comet of 1556, although of great brilliancy, was remarkable for the absence of a tail. This object was supposed by some to be identical with the comet of 1264, and on this hypothesis its return was predicted between the years 1857 and 1861. It has, however, not yet appeared, and it now seems probable that the two comets are not the same object. In the year 1618 a magnificent comet appeared with a tail over a hundred degrees in length. It is said to have been reddish in colour and to have been visible in daylight.

The great comet of 1680, which was observed by Sir Isaac Newton, was remarkable for its near approach to the sun. It had a tail about ninety degrees in length, the real length being about a hundred and twenty millions of miles. It approached the sun so closely when passing through perihelion that, had its flight been then arrested, it would have fallen into the sun in about three minutes! At this time the heat to which it was subjected must have been intense, a heat computed by Sir Isaac Newton at about two thousand times that of red-hot iron! But it passed safely through the ordeal, and swept away into space, probably not to return to the sun's vicinity for several thousand years. It was first seen by G. Kirch, who supposed it to be a return of the comet of B.C. 44, and also identical with the comets of A.D. 531 and 1106; but this seems very improbable.