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Altair is one of the stars from which the moon's distance is taken for computing longitude at sea. Its mean declination is nearly 80 N., and when on the meridian, it occupies nearly the same place in the heavens that the sun does at noon on the 12th day of April. It culminates about 6 minutes before 9 o'clock, on the last day of August. It rises acronycally about the beginning of June.
Ovid alludes to the rising of this constellation; or, more probably, to that of the principal star, Altair:
"Now view the skies,
"Among thy splendid group
The northernmost star in the line, next above Altair, is called Tarazed. In the wing of the Eagle, there is another row composed of three stars, situated 40 or 50 apart, extending down towards the southwest; the middle one in this line is the smallest, being only of the 4th magnitude; the next is of the 3d magnitude, marked Delta, and situated 8° S. W. of Altair.
As you proceed from Delta, there is another line of three stars of the 3d mag. nitude, between 50 and 60 apart, extending southerly, but curving a little to the west, which mark the youthi Antinous. The northern wing of the Eagle is not
inguished by any conspicuous st
Zeta and Epsilon, of the 3d magnitude, situated in the tail of the Eagle, are about 20 apart, and 12° N. W. of Altair. The last one in the tail, marked Epsilon, is on the same meridian, and culminates the same moment with Gamma, in the Harp.
From Epsilon, in the tail of the Eagle, to Theta, in the wrist of Antinous, may be traced a long line of stars, chiefly of the 3d magnitude, whose letter names are Theta, Eta, Mu, Zeta, and Epsilon. The direction of this line is from S. E. to N. W., and its length is about 250.
Eta is remarkable for its changeable appearance. Its greatest brightness continues but 40 hours; it then gradually diminishes for 66 hours when its lustre remains stationary for 30 hours. It then waxes brighter and brighter, until it appears again as a star of the 3d magnitude.
From these phenomena, it is inferred that it not only has spots on its surface, like our sun, but that it also turns on its axis.
Similar phenomena are observable in Algol, Beta, in the Hare, Delta, in Cepheus, and Omicron, in the Whale, and many others.
"Aquila the next,
Divides the ether with her ardent wing:
HISTORY.-Aquila, or the Eagle, is a constellation usually joined with Antinous. Aquila, is supposed to have been Merops, a king of the island of Cos, in the Archipelago, and the husband of Clymene, the mother of Phaeton; this monarch having been transformed into an eagle, and placed among the constellations. Some have imagined that Aquila was the eagle whose form Jupiter assumed when he carried away Ganyinede; others, that it represents the eagle which brought nectar to Jupiter while he lay concealed in the cave at Crete, to avoid
Of what importance is this star at sea? What is its declination? What place does it occupy in the heavens when on the meridian, and when does it culminate? When does it rise acronycally? Describe the position of Tarazed. Describe the row of stars in the wing of the Eagle. Describe the row of stars which mark the youth_Antinous. What stars in the northern wing? Describe Zeta and Epsilon. When is Epsilon on the meridian? What long ine of stars terminates at Epsilon? What are the direction and extent of this line? Describe the remarkable appearance of Eta. What is inferred from these phenomena?
the fury of his father, Saturn. Some of the ancient poets say, that this is the eagle which furnished Jupiter with weapons in his war with the giants:
"The tow'ring Eagle next doth boldly soar,
The eagle is justly styled the "sovereign of birds," since he is the largest, strongest, and swiftest of all the feathered tribe that live by prey. Homer calls the eagle, "the strong sovereign of the plumy race;" Horace styles him
"The royal bird, to whom the king of heaven
And Milton denominates the eagle the "Bird of Jove." Its sight is quick. strong and piercing, to a proverb: Job xxix. 28, &c.
"Though strong the hawk, though practis'd well to fly,
An eagle when deserting human sight,
Antirous is a part of the constellation Aquila, and was invented by Tycho Brahe. Antinous was a youth of Bithynia, in Asia Minor. So greatly was his death lamented by the emperor Adrian, that he erected a temple to his memory, and built in honour of him a splendid city, on the banks of the Nile, the ruins of wh are still visited by travellers with much interest.
DIRECTIONS FOR TRACING THE CONSTELLATIONS WHICH ARE ON THE MERIDIAN IN SEPTEMBER.
THE DOLPHIN.-This beautiful little cluster of stars is situated 13° or 140 N. E. of the Eagle. It consists of eighteen stars, including five of the 3d magnitude, but none larger. It is easily distinguished from all others, by means of the four principal stars in the head, which are so arranged as to form the figure of a diamond, pointing N. E. and S. W. To many, this cluster is known by the name of Job's Coffin; but from whom, or from what fancy, it first obtained this appellation,
is not known.
Where is the constellation Delphinus situated? What are the number and magni tule of its stars? How is this constellation distinguished from all others? What sin gular name is sometimes given to this cluster, and whence was it derived?
There is another star of the 2d magnitude, situated in the body of the Dolphin, about 3° S. W. of the Diamond, and marked Epsilon. The other four are marked Alpha, Beta, Gamma, Delta. Between these are several smaller stars, too small to be seen in presence of the moon.
The mean declination of the Dolphin is about 150 N. It comes to the meridian the same moment with Deneb Cygni, and about 50 minutes after Altair, on the 16th of September.
"Thee I behold, majestic Cygnus,
On the inarge dancing of the heavenly sea,
HISTORY.-The Dolphin, according to some mythologists, was made a constellation by Neptune, because one of these beautiful fishes had persuaded the goddess Amphitrite, who had made a vow of perpetual celibacy, to become the wife of that deity; but others maintain, that it is the dolphin which preserved the famous lyric poet and musician Arion, who was a native of Lesbos, an island in the Archipelago.
He went to Italy with Periander, tyrant of Corinth, where he obtained immense riches by his profession. Wishing to revisit his native country, the sailors of the ship in which he embarked, resolved to murder him, and get possession of his wealth. Seeing them immoveable in their resolution, Arion begged permission to play a tune upon his lute before he should be put to death. The melody of the instrument attracted a number of dolphins around the ship; he immediately precipitated himself into the sea; when one of them, it is asserted, carried him safe on his back to Tænarus, a promontory of Laconia, in Peloponnesus; whence he hastened to the court of Periander, who ordered all the sailors to be crucified at their return.
"But, (past belief,) a dolphin's arched back
When the famous poet Hesiod was murdered in Naupactum, a city of Ætolia, in Greece, and his body thrown into the sea, some dolphins, it is said, brought back the floating corpse to the shore, which was immediately recognised by his friends; and the assassins being afterwards discovered by the dogs of the departed bard, were put to death, by immersion in the same sea.
Taras, said by some to have been the founder of Tarentum, now Tarento, in the south of Italy, was saved from shipwreck by a dolphin; and the inhabitants of that city preserved the memory of this extraordinary event on their coin.
The natural shape of the dolphin, however, is not incurvated, so that one might ride upon its back, as the poets imagined, but almost straight. When it is first taken from the water, it exhibits a variety of exquisitely beautiful but evanescent. tints of colour, that pass in succession over its body until it dies. They are an extremely swift-swimming fish, and are capable of living a long time out of water; in fact, they seem to delight to gambol, and leap out of their native element.
"Upon the swelling waves the dolphins show
Their bending backs; then swiftly darting go,
THE SWAN.-This remarkable constellation is situated in the Milky-Way, directly E. of Lyra, and nearly on the same
Mention some other stars in the Dolphin, What is the mean declination of the Dolphin, and when is it on the meridian? In what part of the heavens is the constellation Cygnus situated?
meridian with the Dolphin. It is represented on outspread wings, flying down the Milky-Way, towards the southwest.
The principal stars which mark the wings, the body and the bill of Cygnus, are so arranged, as to form a large and regular Cross; the upright piece lying along the MilkyWay from N. E. to S. W., while the cross piece, representing the wings, crosses the other at right angles, from S. E. to N. W.
Arided, or Deneb Cygni, in the body of the Swan, is a star of the 1st magnitude, 24° E. N. E. of Lyra, and 30° directly N. of the Dolphin. It is the most brilliant star in the constellation. It is situated at the upper end of the cross, and comes to the meridian at 9 o'clock, on the 16th of September.
Sad'r, is a star of the 3d magnitude, 6° S W. of Deneb, situated exactly in the cross, or where the upright piece intersects the cross piece, and is about 20° E. of Lyra.
Delta, the principal star in the west wing, or arm of the cross, is situated N. W. of Sad'r, at the distance of little more than 80, and is of the 3d magnitude. Beyond Delta, towards the extremity of the wing, are two smaller stars about 50 apart, and inclining a little obliquely to the north; the last of which reaches nearly to the first coil of Draco. These stars mark the west wing; the east wing may be traced by means of stars very similarly situated.
Gienah, is a star of the 3d magnitude, in the east wing, just as far east of Sad'r in the centre of the cross, as Delta is west of it. This row of three equal stars, Delta, Sad'r, and Gienah, form the bar of the cross, and are equidistant from each other, being about 80 apart. Beyond Gienah on the east, at the distance of 60 or 7° there are two other stars of the 3d magnitude; the last of which marks the extremity of the eastern wing.
The stars in the neck are all too small to be noticed. There is one, however, in the beak of the Swan, at the foot of the cross, called Albireo, which is of the 3d magnitude, and can be seen very plainly. It is about 16° S. W. of Sad'r, and about the same distance S. E. of Lyra, with which it makes nearly a right angle.
"In the small space between Sad'r and Albireo," says Dr. Herschel, "the stars in the Milky Way seem to be clustering into two separate divisions; each division containing more than one hundred and sixty-five thousand stars."
Albireo bears northerly from Altair about 20°. Immediately south and southeast of Albireo, may be seen the Fox and GOOSE; and about midway between Albireo and Altair, there may be traced a line of four or five minute stars, called the ARROW; the head of which is on the S. W., and can be distinguished by means of two stars situated close together.
According to the British catalogue, this constellation contains eighty-one stars, including one of the 1st or 2d magnitude, six of the 3d, and twelve of the 4th. The author of the following beautiful lines, says there are one hundred and seven.
"Thee, silver Swan, who, silent, can o'erpass?
How is it represented? What remarkable figure is formed by its principal stars? Describe the position and appearance of Arided, or Deneb Cygni. When does it culminate at 9 o'clock? Describe the position of Sad'r. Describe Delta, What stars beyond Delta? What stars in the east wing? What stars form the bar of the cross? What stars beyond Gie on east? Describe the stars in the neck and bill of the Swan. How is the star in the bill situated with respect to Sad'r and Lyra? What clusters south and southeast of Albireo? What are the number and magnitude of the stars in the Swan ?
Of the fair Milky-Way distinguish'd; one
Astronomers have discovered three variable stars in the Swan. Chi, situated in the neck, between Beta and Sad'r, was first observed to vary its brightness, in 1686. Its periodical changes of light are now ascertained to be completed in 405 days. Sad'r is also changeable. Its greatest lustre is somewhat less than that of a star of the 3d magnitude, and it gradually diminishes till it reaches that of the 6th. Its changes are far from being regular, and, from present observations, they do not seem to recur till after a period of ten years or more.
A third variable star was discovered in the head on the 20th of June, 1670, by Antheline. It appeared then to be of the 3d magnitude, but was so far diminished in the following October, as to be scarcely visible. In the beginning of April, 1671, it was again seen, and was rather brighter than at first. After several changes, it disappeared in March, 1672, and has not been observed since.
These remarkable facts seem to indicate, that there is a brilliant planetary system in this constellation, which, in some of its revolutions, becomes visible
HISTORY.-Mythologists give various accounts of the origin of this constellation. Some suppose it is Orpheus, the celebrated musician, who, on being murdered by the cruel priestess of Bacchus, was changed into a Swan, and placed near his Harp in the heavens. Others suppose it is the swan into which Jupiter transformed himself when he deceived Leda, wife of Tyndarus, king of Sparta. Some affirm that it was Cicnus, a son of Neptune, who was so completely invul. nerable that neither the javelins nor arrows, nor even the blows of Achilles, in furious combat, could make any impression.
"Headlong he leaps from off his lofty car,
And in close fight on foot renews the war;-
But when Achilles saw that his darts and blows had no effect on him, he im. mediately threw him on the ground and smothered him. While he was attempt. ing to despoil him of his armour, he was suddenly changed into a swan.
"With eager haste he went to strip the dead;
Had turn'd it to a bird that bears his name."
According to Ovid this constellation took its name from Cygnus, a relative of Phaeton, who deeply lamented the untimely fate of that youth, and the melancholy end of his sisters, who, standing around his tomb, wept themselves into poplars.
"Cicnus beheld the nymphs transform'd, allied
All Cicnus now into a swan was turn'd."-Ovid's Met. b. ii.
What variable stars have astronomers discovered in this constellation? Which of these was first discovere to be variable 686 In what period are its periodical changes of light completed? Describe the appearance of Sud'r. Describe the one discovered in 1670. What do these remarkable facts indicate?