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popular dread. The comet appeared at the close of the year 1680, and continued visible till March, 1681, when it disappeared from terrestrial eyes. Flamstead, Halley, Newton, Bernoulli, and Cassini, were all engaged in observing it, and few appearances of the kind were more imposing in appearance, or attractive in scientific interest. Its magnitude was immense. Its tail or train - reached up to the zenith, when the body of the comet had set below the horizon, so as to extend over more than 180 degrees of the heavens. The length of this train was found to be 123,000,000 of miles, and in two days the nucleus emitted an additional extent of train equal to 60,000,000 of miles. Like a wrathful messenger it thus overspread the sky, and shot into the depths of far space its luminous appendage. Its rapidity of motion was almost incredible, for it spun along at the rate of 800,000 miles in an hour. This, however, was its velocity only when near the sun ; far removed from his beams, its pace is that of a snail compared with a race-horse, as if the cold regions into which it finds its way, benumb its faculties, and congeal its blood ; and like some of the lesser creatures of our own earth, it passes a winter of sluggish torpidity. According to Newton, this comet came within 144,000 miles of the sun's body, a proximity sufficient not only to scorch, but utterly destroy such a planet as the earth ; but in the case of the comet, it seemed only to revive it, and send it forth with renewed brilliancy and increased magnitude. If the motion of the comet had been stopped when in this position, it would have closed with the sun in three minutes--its velocity, however, prevented such a catastrophe, by constantly changing its place in reference to the sun's attraction. There is no body with which we are acquainted, but would have been dissipated at such a temperature as this mass was subjected to. Newton estimated it at two thousand times the heat of redhot iron.

In an historical point of view, this comet had several points of interest. It is believed to have been the one which appeared just after Cæsar's death, and also in the reign of Justinian, in the year 531, and again in the year

1106, in the reign of Henry II. Comparing these dates, and taking into account the elements of the comet's orbit as ascertained by the astronomers of 1680, it seems to have a period of 574 years ; at the expiration of which, it appears again in our sky. If this is correct, this strange visitant will not be seen again till the year 2255. During the great interval between one appearance and another, this comet travels some 40,000,000,000 of miles, the extreme end of its orbit being 13,000,000,000 of miles from the sun. And yet even when removed to that distance from the solar | luminary, the lamp of the comet is not quenched, its life-blood still flows and energises, and it bas strength left, spite of cold and darkness, and isolation from the warm, social worlds which roam together in the planetary system, to dash up again to the source of light and heat, and receive a new influx of life and power, at the very edge of that blazing furnace.

The prediction of the return of comets is one of those achievements of mathematical astronomy which we have ceased to regard with wonder. The rate of a comet's motion, and the shape of its orbit being ascertained, astronomers are able to say, when it may be again expected, and while there is no pretence of prophecy in these announcements, their fulfilment often creates surprise, and is at all times interesting. The first comet, whose return was predicted, fulfilled the prediction by appearing in 1682, a year after the disappearance of the one just noticed. Though far inferior to the former in dimensions and splendour, it has, from other reasons, become one of the most interesting bodies of the system. It presented a tail extending through thirty degrees of the hemisphere; and while science watched its movements, the eyes of the populace watched it without alarm ; a sense of security following the safe departure of the preceding. With this comet Halley associated similar appearances in the years 1531 and 1607, by a comparison of elements, says the present astronomer royal, such as none but Halley could have performed ; its period was stated at seventy-five years.

Continuing these analyses, Halley ventured to foretel its appearance in 1758; and identified it further as having

appeared in the years 1155, 1230, 1305, 1380, 1456,1531,1607
and 1682, between each of which dates a period of seventy-
five or seventy-six years intervenes. The year 1758
approached, and the French astronomers, Lalande and
Clairaut, assisted by Madame Lalande, began to reconsider
its elements, and asserted that it would be later in
appearing than was expected, owing to the attraction of
Jupiter and Saturn, which the comet would have to pass.
The whole of Europe was on the alert ; and on Christmas-
day, 1758, the anticipations of Halley and the French
astronomers, were realized by the discovery of the comet.
It passed its perihelion, the point of its orbit nearest the
sun, on the 12th of March, 1759, exactly within the limits
determined by the French astronomers. According to
subsequent announcements the comet appeared again in
1835, and passed its perihelion in November of that year ;
on each occasion proving, by its peaceful passage, and
quiet, though swift departure, that the lines,

A pathless comet, and a curse,
The menace of the universe;
Still rolling on with innate force,

Without a sphere, without a course :
are too fictitious even for the license of poetry-these
bodies being as subject to law as the other bodies of the
system, and so far from Menacing," courting and
engaging intellectual enquiry.

One of the most wonderful comets of modern times was that of 1743, which had six tails, all curved in the same direction, and diverging from its body. It first appeared in December, 1743, and continued visible during the spring following. On the 1st of February it was more brilliant than the star Sirius; on the 8th it rivalled Jupiter; and was visible even when the sun shone at the beginning of the next month. By selecting suitable places, many persons saw it at mid-day without glasses. Its six separate tails spread out like a fiery fan, and each measuring from thirty to forty degrees in length, and four in width ; the edges were bright and sharp, the middle faint, and the intervening spaces as sombre as the rest of

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the firmament the stars shining through them. This comet was frequently seen in Switzerland, with the nucleus far below the horison, and the six tails extending twenty or thirty degrees above it. On the whole it was one of the most striking exhibitions on record.

[graphic]

COMET OF 1743. In 1811 the finest comet which the present generation have yet seen appeared. It was beheld in this country in the beginning of September, and was visible for more than three months to the naked eye, shining with great splendour, the observed of all observers. It was a comet of first class, and had a tail of 123,000,000 miles in length, by 15,000,000 in breadth. Supposing the body of the comet to have been placed on the sun, its tail would have extended sufficiently far to pass Mercury, Venus and the earth, and to approach the neighbourhood of Mars. It came no nearer to us than 141,000,000 of miles, so that if its tail had been pointed towards the earth, it would not have touched it by 18,000,000 of miles. Various estimates have been formed as to the period of its revolution, and periods ranging from three thousand and fifty-six to four thousand two hundred and thirty

[graphic]

SO

COMET OF 1811.

seven years assigned it. Even the last of these periodsconstituting only one year of the comet's history-overwhelms us with its magnitude, and carries back the mind to the infant state of man when cities were unfounded, and fable was lisped from the lips of men then in the first dawn of civilization. Yet in this journey of three thousand and fifty-six years in which it descends deeply into space, the influence of the sun follows it; not merely lighting up its vaporous body, but holding it by the power of attraction, from passing into other systems. The appearance of this comet was an ornament to the evening sky. “Many a reaper

late in the harvest field stayed his hand, and many a peasant homeward bouuu supped m his way, to gaze upon the celestial novelty as it grew into distinctness with the declining day," the “ Ettric Shepherd ” has left some lines descriptive of the impression made on his mind by this mysterious visitor.

How lovely is this wilder'd scene,

As twilight from her vaults so blue,
Steals o'er soft Yarrow's mountain green,

To sleep embalmed in midnight dew !
All hail, ye hills, whose towering height,

Like shadows, scud the yielding sky;
And thou, mysterious guest of night,

Dread traveller of immensity!

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