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Better taught, thou didst despise
Earthly honour and renown;
Rest, from thy labours rest,
In heaven for ever blest!
Where thy Chief hath gone before;
Thou art more than conqueror.
J. W. T.
DECEMBER, 1854. By A. GRAHAM, Esq., Markree Observatory, Collooney. In the earlier part of this month, MERCURY rises two hours before the Sun: the student may thus enjoy a sight which many an ardent lover of astronomy (and among the rest Copernicus) never witnessed. Its intense and silvery light, its very minuteness, and the difficulty of obtaining a glimpse of it with the naked eye, tend to inspire an interest from age to age perhaps unsurpassed by any of the other planets. The revelations of the telescope, and its handmaid analysis, in this case, as in many others, considerably heighten that interest. We insert a brief summary of what is now known concerning this planet. As it revolves round our central body in an orbit considerably within that of the Earth, it presents successively all the phases of the Moon, but in a reversed order. After inferior conjunction, it appears as a fine crescent on the western side of the Sun, and gradually recedes, diminishing in diameter, but increasing the relative magnitude of its illuminated parts, until it attains its greatest western elongation from the Sun, between 16° and 29°, when its form is that of the Moon at the end of her third quarter. After this it becomes gibbous, approaching full toward superior conjunction, and is soon lost in the Sun's rays, to reappear on the eastern side, and reverse the series of changes ---full, gibbous, semicircle, crescent,-until it again reaches inferior conjunction, after a lapse of about one hundred and eighteen days: this interval is termed a synodic revolution. As it moves nearly in the plane of the Earth's orbit, and we consequently view its path very obliquely, the planet seems to oscillate on either side of the Sun's disc nearly in an arc of the ecliptic, whose mean value is 45°; the oscillation from left to right, that is, from east to west of the Sun, being performed in less time than that in the opposite direction. With the exception of the small bodies between Mars and Jupiter, thirty-one of which have now been registered, Mercury is the smallest primary planet in our system. His diameter is 3140 miles, about two-fifths of the Earth’s diameter, not quite once-and-a-half the diameter of our Moon. Of course its volume is to that of the Earth nearly as the cubes of two and five; that is, this planet is sixteen times less than the Earth: but it is composed of materials upwards of two-and-a-half times denser, so that the Earth is little more than six times weightier than Mercury. It is worthy of remark, that the mean density of this planet is about equal to that of its cognominal metal. Our readers need not to be informed that there is no more ground for inferring that mercury is the material of which this planet is composed, than a distinguished philosopher of our own times has for arguing that Jupiter is a sphere of water, from the fact that his mean density is five times less than that of the Earth, or almost precisely equal to that of water. Nor are we to infer that, because the Sun's light and heat at Mercury are nearly seven times greater than at the Earth, his seas, if seas there be, are huge caldrons of boiling water: atmospheric influences may so modify it as to make this planet as suitable for habitation as our own. The length of the day differs very little from ours. Mercury rotates in 24h. 5m. 28s.; the Earth in 23h. 56m. 4s. : the motion of the latter round the Sun makes the length of the day 3m. 56s. greater than the time of rotation; the more rapid motion of the former causes a difference of about sixteen minutes between the solar day and the sidereal, Themean distance of this planet from the Sun is 364 millions of miles; to this corresponds the period of revolution, eighty-eight days, by the third of Kepler's Laws: "The squares of the times of revolution are as the cubes of the mean distances from the Sun.” Analysis has shown that this proportion is only approximate, as it does not take into account the reaction of the planets upon the Sun. Compared with the larger planets of our system, the orbit of Mercury is very eccentric: his greatest and least distances from the Sun differ by 15 millions of miles; they are, in round numbers of millions, 44 and 29, respectively. The orbital motion is upwards of one hundred thousand miles per hour. Knowing the mass and diameter of this planet, relatively to the Earth, the inference may be easily deduced that a body at its surface weighs one-tenth more than would the same body at the surface of the Earth,
MERCURY is now receding from the Earth and Sun. The distances from the former on the first and last days of this month, are 84 and 132 millions of miles ; and from the latter, 32 and 44 millions, respectively. On the 2d, at 2h. in the afternoon, he will be at his greatest northern distance from the plane of the Earth's orbit; on the 26th, at lh, in the afternoon, in that plane. The form of the
planet will be a crescent till noon of the 7th, when he will have reached his greatest western elongation, 21° : after this it will be gibbous. Seen from Mercury, Venus is receding from the Sun westward, and is increasingly large and splendid. Somewhat eastward of Venus are Mars and Jupiter. The Earth, though far inferior to Venus, is a fine object, apparently approaching the Sun on the eastern side. Saturn is very close to the Earth.
Venus is too close to the Sun, and too distant from the Earth, to be visible. She will be in superior conjunction with the Sun on the 13th, at half-past ten in the morning. Mercury is the evening star to Venus. Toward the end of the month he will have reached his greatest elongation; and, as he is approaching Venus, he will then and subsequently increase in brightness. Mars and Jupiter will have nearly the same appearance as from Mercury.
MARS is near the Sun on the eastern side.
JUPITER is still visible after sunset; but is too low to bear examination with telescopes of high power.
SATURN will be in opposition to the Sun on the 4th, at 7h, in the afternoon. On that night he will be considerably obscured by the proximity of the full Moon. A few nights will suffice to restore him to his splendour; and those who have the means will do well to take advantage of the favourable position, and feast their eyes and their minds by contemplating this singular product of creative skill. At the end of the year he will be only 2° distant from Aldebaran. His ring appears almost precisely as it did in November. The minor axis is one second seven-tenths greater than the diameter of the sphere: thus, the southern edge of the latter will appear on the ring, nearly one second within its edge.
URANUS will cross the meridian, at an altitude of 54°, on the evening of the 1st, at four minutes past ten; on the 16th, at three minutes past nine; and on the 31st, at three minutes past eight.
NEPTUNE will cross the meridian, at an altitude of 31o, on the evening of the 1st, at eighteen minutes past six; 16th, at twenty minutes past five; 31st, at twenty-two minutes past four. His distance, on the 16th, is 2,871 millions of miles. To traverse this space, light requires 4h. 9m. 45s.: it comes from the Moon to us in less than a second and a half.
The Sun enters Capricorn on the 22d, at 3h. in the morning, and the Winter quarter commences.
"Ah! why reposest thou so pale,
Thou cherish'd fatherland?
Thy glowing vestment bland ?
“ On all thy trees, on every bough,
Where'er our eyes alight;
With glittering hoar.frost bright.
“Our Father kind, who dwells above,
He watches over thee;
New strength, new light to see."
RISING AND SETTING OF THE SUN, FOR THE PARALLELS OF THE
Rises. Sets. Rises. Sets. Rises. Sets. Rises. Sets. Rises. Sets. h. m. h. m. h. m. h.m.h.m. h. m. b. m. h, m. h. m. h, m. 17 36 4 2 7 45 3 537 55 3 43 8 6 3 32 8 19 3 19 117 48 3 59 7 58 3 498 9 3 38 8 21 3 268 35 3 12 217 56 4 18 6 3 518 17 3 40 8 30 3 278 45 3 12 31 7 59 4 8.8 8 3 58 8 19 3 47 8 32 3 35 8 46 3 21
SUN AND PLANETS AT GREENWICH.
MERCƯRY. VENUS. MARS. JUPITER. SATURN. URANUS.
VOL. XVIII. OF THE SECOND SERIES.
A soldier's trust, 5051
Chaucer, biographic sketch of, 193
Chinese insurgents, an imposture of
journey through the interior of, 537 Coinage, English, account of, 454
of Messrs. Harper, publishers, of Coloured glass windows, hints for, 154
an American erratum noticed, 138 August of last year, 333-parabolic
Constantine the Great, note respecting,
Crystal Palace, Sabbath-keeping in
the, 474-books on the, noticed, 476
Dante, biographic sketch of, 337
table of the orbits of, explained, 140, Dionysius, St., of Zante, history of,
Eagle and swan, 64
as a captive, 505--honourable con- Eclipse of the moon, 237, 525-of the
sun, 237, 526
Educated men, obligations of : an ad.
dress, by the Rev. John Allison,
New Brunswick, 156
Embalming of Joseph, 368
Evangelical religion, popular carica-
tures of, 207
Fashion, the miseries of, 281
Mansour and Khasi-moullah, 324- explained, 56
Fletcher, Mrs., the "Life" of, a fa-
vourite book with the ex.Queen of