inay be readily distinguished, abcat 20° S. E. of Aries, by means of five remarkable stars, 4° and 5° apart, and so situated as to form a regular pentagon. The brightest of these is Menkar, of the 2d magnitude, in the nose of the Whale. It occupies the S. E. angle of the figure. It is 3° N. of the equinoctial, and 15° E. of El Rischa in the bight of the cord between the Two Fishes. It is directly 37° S. of Algol, and nearly in the same direction from the Fly. It makes an equilateral triangle with Arietis and the Pleiades, being distant from each about 23° S., and may otherwise be known by a star of the 3d magnitude in the mouth, 3° W. of it, called Gamma, placed in the south middle angle of the pentagon.

56. Nu is a star of the 4th magnitude, 4° N. W. of Gamma, and these two constitute the S. W. side of the pentagon in the bead of the Whale, and the N. E. side of a similar oblong figure in the neck.

Three degrees S. S. W. of Gamma, is another star of the 3d magnitude in the lower jaw, marked Delta, constituting the E. side of the oblong pentagon; and 6° S. W. of this, is a noted star in the neck of the Whale, called Mira, or the "wonderful star of 1596," which forms the S. E. side. This variable star was first noticed as such by Fabricius, on the 13th of August, 1596. It changes from a star of the 2d magnitude so as to become invisible once in 234 days, or about 7 times in 6 years. Herschel makes its period 331 days, 10 hours, and 19 minutes; while Hevelius assures us that it once disappeared for 4 years; so that its true period, perhaps, has not been satisfactorily determined.

The whole number of stars ascertained to be variable amounts to only 15; while those which are suspected to be variable, amount to 37.

57. Mira is 7° S. S. E. of El Rischa, in the bend or knot of the ribbon which connects the Two Fishes. Ten degrees S. of Mira, are 4 small stars, in the breast and paws, about 3° apart, which form a square, the brightest being on the E. Ten degrees S. W. of Mira is a star of the 3d magnitude, in the heart, called Baten Kaitos, which makes a scalene triangle with two other stars of the same magnitude 7° and 10° W. of it; also, an equilateral triangle with Mira and the easternmost one in the square.

star? Position? Name? 56. Size and Position of Nu? Delta? Mira? Position? Peculiarity? When, and by whom first noticed? Period and extent of variability? Whole number of variable stars? 57. Buten Kaitos? Position with regard to Mira. Feather stars?

A great number of geometrical figures may be formed from the stars in this, and in most of the other constellations, merely by reference to the maps; but it is better that the student should exercise his own ingenuity in this way with reference to the stars themselves, for when once he has constructed a group into any letter or figure of his own invention, he never will forget it.

The teacher should therefore require his class to commit to writing the result of their own observations upon the relative position, magnitude and figures of the principal stars in each constellation. One evening's exercise in this way will disclose to the student a surprising multitude of crosses, squares, triangles, arcs and letters, by which he will be better able to identify and remember them, than by any instructions that could be given. For example: Mira and Baten in the Whale, about 10° apart, make up the S. E. or shorter side of an irregular square, with El Rischa in the node of the ribbon, and another star in the Whale as far to the right of Baten, as El Rischa is above Mira. Again,

There are three stars of equal magnitude, forming a straight line W. of Baten; from which, to the middle star is 10°, thence to the W. one 12%; and 8° or 9° S. of this line, In a triangular direction, is a bright star of the second magnitude in the coil of the tail, called Diphda.

In a southerly direction, 25° below Diphda, is Alpha in the head of the Phenix, and about the same distance S. W. is Fomalhaut, in the mouth of the Southern Fish, forming together a large triangle, with Diphda in the vertex or top of it.

That fine cluster of small stars S. of the little square in the Whale, constitutes a part of a new constellation called the Chymical Furnace. The two stars N. E., and the three to the southward of the little square, are in the river Eridanus.

HISTORY.

This constellation is of very early antiquity: though most writers consider it the famous sea-monster sent by Neptune to devour Andromeda because her mother Cassiopeia had boasted herself fairer than Juno or the Sea Nymphs; but slain by Perseus and placed among the stars in honor of his achievement.

"The winged hero now descends, now soars,
And at his pleasure the vast monster gores.
Deep in his back, swift stooping from above,
His crooked sabre to the hilt he drove."

It is quite certain, however, that this constellation had a place in the heavens long prior to the time of Perseus. When the equinoctial sun in Aries, which is right over the head of Cetus, opened the year, it was denominated the Preserver, or Deliverer, by the idolaters of the East. On this account, according to Pausanius, the sun was worshipped, at Eleusis, under the name of the Preserver or Saviour.

"With gills pulmonic breathes the enormous whale,

And spouts aquatic columns to the gale;

Sports on the shining wave at noontide hours,

And shifting rainbows crest the rising showers."-Darwin.

TELESCOPIC OBJECTS.

1. B CETI-A DOUBLE STAR; R. A. 0h. 35m. 34s.; Dec. S. 18° 51′ 9′′. A 2, yellow; B 12, pale blue.

2. Y CETI A CLOSE DOUBLE STAR in the Whale's mouth; R. A. 2h. 85m. 01s.; Dec. N. 2° 33' 5". A 3, pale yellow; B 7, lucid blue; the colors finely contrasted.

8. A DOUBLE STAR in the Whale's eye; y R. A. 2h. 27m. 29s.; Dec. N. 4° 58′ 5′′. A 4%, pale yellow; B 15, blue.

4. A LONG NARROW NEBULA, of a pale, milky tint; R. A. Oh. 39m. 45s.; Dec. S. 26° 10' 1". It is situated in the space south of the tail of Cetus, near a line drawn from a Andromeda to B Ceti. Discovered by Miss Herschel, in 1783.

5. A PLANETARY NEBUĻA; R. A. 2h. 19m. 25s.; Dec. S. 1° 51′ 6′′; in the middle of the Whale's neck.

6. A BRIGHT ROUND NEBULA; R. A. 1h. 28m. 20s.; Dec. S. 7° 41' 8". Registered by Sir W. Herschel, 1785. It is just above the Whale's back.

Lequence?

HISTORY.--Antiquity? Its original name? When, and why? What worship in con TELESCOPIO OBJECTS.-Beta? Gamma? Nu? Nebulæ ?

from y

7. A ROUND STELLAR NEBULA, near & in the Whale's lower jaw, and about 2 on a line towards E, or south by west. A very distant object, classed by Sir W. Herschel, as 910 times as distant as stars of the first magnitude.

PERSEUS, ET CAPUT MEDUSÆ.-MAP III. AND IV.

58. PERSEUS is represented with a sword in his right hand, the head of Medusa in his left, and wings at his feet. It is situated directly N. of the Pleiades and the Fly, between Andromeda on the W. and Auriga on the E. Its mean declination is 46° N. It is on the meridian the 24th of December. It contains, including the head of Medusa, 59 stars, two of which are of the 2d magnitude, and four of the 3d. According to Eudosia, it contains, including the head of Medusa, 67 stars.

"Perseus next,

Brandishes high in heaven his sword of flame,
And holds triumphant the dire Gorgon's head,
Flashing with fiery snakes! the stars he counts
Are sixty-seven; and two of these he boasts,
Nobly refulgent in the second rank-

One in his vest, one in Medusa's head."

59. THE HEAD OF MEDUSA is not a separate constellation, out forms a part of Perseus. It is represented as the trunkless head of a frightful Gorgon, crowned with coiling snakes, instead of hair, which the victor Perseus holds in his hand. There are, in all, about a dozen stars in the head of Medusa; three of the 4th magnitude, and one, varying alternately from the 2d to the 4th magnitude. This remarkable star is called Algol. It is situated 12° E. of Almaack, in the foot of Andromeda, and may be known by means of three stars of the 4th magnitude, lying a few degrees S. W. of it, and forming a small triangle. It is on the meridian the 21st of December; but as it continues above the horizon 18 hours out of 24, it may be seen every evening from September to May. It varies from the 2d to the 4th magnitude in about 3 hours, and back again in the same time; after which it remains steadily brilliant for 2 days, when the same changes recur.

The periodical variation of Algol was determined in 1783, by John Goodricke, of York (Eng.), to be 2 days, 20 hours, 45 minutes, and 56 seconds. Dr. Herschel attributes the variable appearance of Algol to spots upon its surface, and thinks it has a motion on its axis similar to that of the sun. He also observes, of variable stars generally :-"The rotary motion of the stars upon their axis is a capital feature in their resemblance to the sun. It appears to me now, that we cannot refuse to admit such a motion, and that indeed it may be as evidently proved as the diurnal motion of the earth. Dark spots,

58. Perseus? How represented? When on the meridian? 59. Head of Medusa? How represented? Number of stars? Situation? Variableness and period? When and by whom cause of variability? Lalande?

Number of stars? Size? What remarkable ce? determined? Supposed

or large portions of the surface less luminous than the rest, turned alternately in certala directions either toward, or from us, will account for all the phenomena of periodical changes in the lustre of the stars, so satisfactorily, that we certainly need not look out for any other cause."

It is said that the famous astronomer Lalande, who died at Paris in 1807, was wont to remain whole nights, in his old age, upon the Pont Neuf, to exhibit to the curious the variations in the brilliancy of the star Algol.

60. Nine degrees E. by N. from Algol, is the bright star Algenib, of the 2d magnitude, in the side of Perseus, which with Almaack, makes a perfect right angle at Algol, with the open part towards Cassiopeia. By means of this strikingly perfect figure, the three stars last mentioned may always be recognized without the possibility of mistaking them. Algenib may otherwise be readily distinguished by its being the brightest and middle one of a number of stars lying four and five degrees apart, in a large semicircular form, curving towards Ursa Major.

Algenib comes to the meridian on the 21st December, 15 minutes after Algol, at which time the latter is almost directly overhead. When these two stars are on the meridian, that beautiful cluster, the Pleiades, is about half an hour E. of it; and in short, the most brilliant portion of the starry heavens is then visible in the eastern hemisphere. The glories of the scene are unspeakably magnificent; and the student who fixes his eye upon those lofty mansions of being, cannot fail to covet a knowledge of their order and relations, and to "reverence Him who made the Seven Stars and Orion."

61. The Milky Way around Perseus is very vivid, being undoubtedly a rich stratum of fixed stars, presenting the most wonder ful and sublime phenomenon of the Creator's power and greatness. Kohler, the astronomer, observed a beautiful nebula near the face of Perseus, besides eight other nebulous clusters in different parts of the constellation.

The head and sword of Perseus are exhibited on the circumpolar map. That very bright star 23 E. of Algol, is Capella in the Charioteer.

HISTORY

Perseus was the son of Jupiter and Danae. He was no sooner born than he was cast into the sea, with his mother; but being driven on the coasts of one of the islands of the Cyclades, they were rescued by a fisherman, and carried to Polydectes, the king of the place, who treated them with great humanity, and intrusted them to the care of the priests of Minerva's temple. His rising genius and manly courage soon made him a favorite of the gods. At a great feast of Polydectes, all the robles were expected to present the king with a superb and beautiful horse; but Perseus, who owed his benefactor much not wishing to be thought less munificent than the rest, engaged to bring him the head of Medusa, the only one of the three Gorgons, who was subject to mortality. The names of the other two were Stheno and Euryale. They were represented with serpents wreathing round their heads instead of hair, having yellow wings and brazen hands; their bodies which grew indissolubly together, were covered with impenetrable scales, and their very looks had the power of turning into stones all those on whom they fixed their eyes.

To equip Perseus for this perilous enterprise, Pluto, the god of the infernal regions, lent him his helmet, which had the power of rendering the wearer invisible. Minerva, the goddess of wisdom, furnished him with her buckler, which was as resplendent as a polished mirror; and he received from Mercury wings for his feet, and a dagger made

60. Algenib? How known? When on the meridian? Where, then, are the Pleiades? What the general aspect of the heavens? 61. Milky Way around Perseus? Observa. tion of Kohler?

HISTORY.-Who was Perseus? What fate at birth, &c.?

of diab

Thus equipped, he mounted into the air, conducted by Mirerva, and came upon tl.c n.sters who, with the watchful snakes about their heads, were all asleep. He approached them, and with a courage which amazed and delighted Minerva, cut off with one blow Medusa's head. The noise awoke the two immortal sisters, but Pluto's helmet rendered Perseus invisible, and the vengeful pursuit of the Gorgons proved fruitless.

"In the mirror of his polished shield
Reflected, saw Medusa slumbers take,

And not one serpent by good chance awake;
Then backward an unerring blow he sped,

And from her body lopped at once her head."

Perseus then made his way through the air, with Medusa's head yet reeking in his hand, and from the blood which dropped from it as he flew, sprang all those innumerable zerpents that have ever since infested the sandy deserts of Libya.

"The victor Perseus, with the Gorgon head,

O'er Libyan sands his airy journey sped,

The gory drops distilled, as swift he flew,

And from each drop envenomed serpents grew."

The destruction of Medusa rendered the name of Perseus immortal, and he was changed into a constellation at his death, and placed among the stars, with the head of Medusa by his side.

TELESCOPIC OBJECTS.

1. a PERSEI-A FINE DOUBLE STAR; R. A. 3h. 12m. 55s.; Dec. N. 49° 17′ 2′′. A 2%1⁄2, brilliant lilac; B9, cinereous. This is Algenib, in the hero's left side.

2. PERSEI, or Algol; R. A. 2h. 57m. 46s.; Dec. N. 41° 20′. A variable Double Star. A 2 to 4, whitish; B 11, purple. The former varies in brightness periodically, from the 2d to the 4th magnitude, and back again to the 2d magnitude, period being 2d. 20h. 48m. 56s.; an object of great interest.

3. Y PERSEI-A WIDE UNEQUAL DOUBLE STAR in the hero's left shoulder; R. A. 2h, 58m. 14s.; Dec. N. 52° 52′ 4′′. A 4, flushed white; B 14, clear blue.

4. d PERSEI-A BRIGHT STAR with a companion in the hero's hip; R. A., 8h. 31m. 33s.; Dec., N. 47° 16' 2". About 3° south-west of a Persei. A 3%, white; B 11, pale blue.

5. & PERSEI-A NEAT DOUBLE STAR in the right knee; R. A. 8h. 47m. 08s.; Dec. N. 39° 32' 4". A 3%, pale white; B 9, lilac; a fine delicate object.

6. PERSEI-A DELICATE QUADRUPLE STAR; R. A. 3h. 44m. 05s.; Dec. N. 81° 24′ 2′′. A 3%, flushed white; B 10, smalt blue; C 12, ash-colored; D 11, blue. It is situated in the right foot, and is designated by Smyth as "an elegant group."

7. PERSEI-A FINE DOUBLE STAR in the head of the figure; R. A. 2h. 89m. 04s.; Dec. N. 55° 13' 5". A 5, orange; B 8%, smalt blue; the colors in fine contrast.

8. A GORGEOUS CLUSTER in the sword handle of Perseus; R. A. 2h. 08m. 588.; Dec. N. 56° 24' 4". It may be seen with the naked eye, and when seen through a good telescope, is one of the most magnificent objects in the heavens. Map VIII., Fig. 25.

9. An EXTENSIVE and rich CLUSTER on the right side of Perseus, in a rich portion of the galaxy. R. A. 3h. 04m. 01s.; Dec. N. 46° 37' 9". Smyth says "it has a gathering spot about 4' in diameter, where the star-dust glows among minute points of light." Herschel says, "the large stars are arranged in lines like interwoven letters.

10. An ELONGATED NEBULA; R. A. 2h. 30m. 25s.; Deo. N. 38° 21′ 3′′; supposed to be a vast ring, seen obliquely. Map VIII., Fig. 26.

11. A pretty compressed OVAL group of stars, in the left knee of Perseus, nearly midway between 2 and μ; R. A. 8h. 58m. 11s.; Dec. N. 49° 04′ 05′′. A well-marked object, surrounded by a curve of larger stars, somewhat in the form of the letter D. Map VIII., Fig. 27.

TELESCOPIC OBJECTS.-Alpha? Beta? Gamma? Clusters? Nebula? Which shown on the map?

Delta?

Epsilon? Zeta? Eta!