« PreviousContinue »
2. A neat DOUBLE STAR on the north extreme of the graduated limb of the instrument; and three-fifths of the distance between Alphard and Denebola; R. A. 10h. 35m. 02s.; Dec. N. 5° 35' 2". A 7, topaz yellow; B 8, smalt blue; a fine object.
3. A bright class ROUND NEBULA on the frame of the instrument; R. A. 10h. 05m. 58s.; Dec. N. 4° 15' 1". A good telescope shows another large but faint nebula near by.
This object is on or near the spot where the Capuchin, De Rheita, fancied he saw the napkin of St. Veronica, in 1783. Captain Smyth has a picture of this wonderful napkin; and Sir J. Herschel remarks that "many strange things were seen among the stars before the use of powerful telescopes became common."
HYDRA AND THE CUP.-MAP IV.
136. HYDRA, (the Water-Serpent,) is an extensive constellation, winding from E. to W. in a serpentine direction, over a space of more than 100 degrees in length. It lies south of Cancer, Leo and Virgo, and reaches almost from Canis Minor to Libra. It contains sixty stars, including one of the 2d magnitude, three of the 3d, and twelve of the 4th.
137. Alphard or Cor Hydra, in the heart, is a lone star of the 2d magnitude, 23° S. S. W. of Regulus, and comes to the meridian at the same time with Lambda, in the point of the sickle, about 20 minutes before 9 o'clock on the 1st of April. There is no other considerable star near it, for which it can be mistaken. An imaginary line drawn from Gamma Leonis through Regulus, will point out Cor Hydra, at the distance of 23°.
138. The head of Hydra may be distinguished by means of four stars of the 4th magnitude, 24° and 4° apart, situated 6° S. of Acubens, and forming a rhomboidal figure. The three upper stars in this cluster form a small arch, and may be known by two very small stars just below the middle one, making with it a very small triangle. The three western stars in the head also make a beautiful little triangle. The eastern star in this group, marked Zeta, is about 6° directly S. of Acubens, and culminates at the same time.
139. When Alphard is on the meridian, Alkes, of the 4th magnitude, situated in the bottom of the Cup, may be seen 24° S. E. of it, and is distinguished by its forming an equilateral triangle with Beta and Gamma, stars of the same magnitude, 6° S. and E. of it. Alkes is common both to Hydra and the Cup. Beta, on the S., is in Hydra, and Gamma, on the N. E., is near the middle of the Cup. A line drawn from Zozma, through Theta
186. Describe Hydra? Its situation? Number and magnitude of its stars? 137. Position and magnitude of Alphard? How pointed out? 138. How is the head of Hydra distinguished? 189. What said of Alkes? Of Beta and Gamma? How is Beta found?
Leonis, and continued 384° directly S. will reach Beta; it is therefore on the same meridian, and will culminate at the same time on the 23d of April.
140. The Cup itself (called also the Crater), may be easily distinguished by means of six stars of the 4th magnitude, forming a beautiful crescent, or semicircle, opening to the W. The center of this group is about 15° below the equinoctial, and directly S. of the hinder feet of Leo. The crescent form of the stars in the Cup is so striking and well defined, when the moon is absent, that no other description is necessary to point them out. Its center comes to the meridian about two hours after Alphard, on the same evening; and consequently, it culminates at 9 o'clock, one month after Alphard does. The remainder of the stars in this constellation may be easily traced by aid of the map.
141. When the head of Hydra is on the meridian, its other extremity is many degrees below the horizon, so that its whole length cannot be traced out in the heavens until its center, or the Cup, is on the meridian.
"Near the equator rolls
O'er the long track of his enormous spires;
Chief beams his heart, sure of the second rank,
The astrologers of the east, in dividing the celestial hosts into various compartments, assigned a popular and allegorical meaning to each. Thus the sign Leo, which passes the meridian about midnight, when the sun is in Pisces, was called the House of the Lions, Leo being the domicil of Sol.
The introduction of two serpents into the constellations of the ancients, had its origin, it is supposed, in the circumstances that the polar one represented the oblique course of the stars, while the Hydra, or Great Snake, in the southern hemisphere, symbolized the moon's course; hence the Nodes are called the Dragon's head and tail to this day.
The hydra was a terrible monster, which, according to mythologists, infested the neighborhood of the lake Lerna, in the Peloponnesus. It had a hundred heads, according to Diodorous; fifty, according to Simonides; and nine, according to the more com monly received opinion of Apollodorus, Hyginus, and others. As soon as one of these heads was cut off, two immediately grew up if the wound was not stopped by fire.
"Art thou proportion'd to the hydra's length,
Who by his wounds received augmented strength?
When one I lopp'd, up sprang a dreadful pair."
To destroy this dreadful monster, was one of the labors of Hercules, and this he easily effected with the assistance of Iolaus, who applied a burning iron to the wounds as soon as one head was cut off. While Hercules was destroying the hydra, Juno, jealous of his glory, sent a sea-crab to bite his foot. This new enemy was soon despatched; and
141. What is said of the
140. How is the Cup distinguished? Is it easily found? extent of Hydra east and west? History of Hydra?
Juno was unable to succeed in her attempts to lessen the fame of Hercules. The conqueror dipped his arrows in the gall of the Hydra, which ever after rendered the wounds inflicted with them incurable and mortal.
This fable of the many-headed hydra may be understood to mean nothing more than that the marshes of Lerna were infested with a multitude of serpents, which seemed to multiply as fast as they were destroyed.
1. a CRATERIS-A star with two very distant companions in the base of the cup; R. A. 10h. 52m. 00s; Dec. S. 17° 26' 9". A. 4, orange tint; B 8, intense blood color; C 9, pale blue.
2. y CRATERIS-A close DOUBLE STAR, in the center of the cup; R. A. 11h. 16m. 54s. ; Dec. S. 16° 48' 3"; A 4, bright white; B 14, grey, with a star of the 11th magnitude following, on a line with A. B. 25' distant.
3. d CRATERIS-A star with a very distant companion, on the cup, midway between Alphard and Spica, but a little south of the line joining them; R. A. 11h. 11m. 21s.; Dec. S. 13° 54' 8". A 31⁄2, pale orange; B 11, pale blue-other small stars in the field.
4. a HYDRA (Cor Hydra)—A bright star in the heart of Hydra with a distant companion; R. A. 1h. 19m. 44s.; Dec. S. 7° 58′ 1′′. A 2, orange tint; B 10, pale green.
5. HYDRA-A star with a distant companion in the head of Hydra; R. A. 8h. 29m, 14s.; Dec. N. 6° 15′ 5′′. A 4, light topaz; B 9, livid-several other stars in the field.
6. & HYDRA-A double star in the head; R. A. 8h. 38m. 18s.; Dec. N. 7° 00′ 2′′. A 4, pale yellow; B 8%, purple.
7. A PLANETARY NEBULA in the middle of the body; R. A. 10h. 17m. 01s.; Dec. S. 17° 50' 6"; greyish white.
URSA MAJOR (THE GREAT BEAR).-MAPS IV. AND VI.
142. URSA MAJOR is situated between Ursa Minor on the north, and Leo Minor on the south. It is one of the most noted and conspicuous in the northern hemisphere. It has been an object of universal observation in all ages of the world.
CONSTELLATIONS ON THE MERIDIAN IN MAY.
The priests of Belus and the Magi of Persia, the shepherds of Chaldea, and the Phonician navigators, seem to have been equally struck with its peculiar outlines. And it is somewhat remarkable, that a remote nation of American Aborigines, the Iroquois, and the earliest Arabs of Asia, should have given to the very same constellation the name of "Great Bear," when there had probably never been any communication between them; and when the name itself is so perfectly arbitrary, there being no resemblance whatever to a bear, or to any other animal.
143. It is readily distinguished from all others by means of a remarkable cluster of seven bright stars, forming what is familiarly termed the Dipper, or Ladle. In some parts of England it is called "Charles' Wain," or wagon, from its fancied resem
Gamma? Delta? Alpha Hydræ? Delta Hydræ?
143. How dis
142. Describe Ursa Major? What remarkable fact as to its name? tinguished? What other names for the Dipper? What remark in small type?
blance to a wagon drawn by three horses in a line. Others call it the Plough. The cluster, however, is more frequently put for the whole constellation, and called simply the Great Bear.
We see no reason to reject the very appropriate appellation of the shepherds, for the resemblance is certainly in favor of the Dipper; the four stars in the square forming the bowl, and the other three the handle.
144. When the Dipper is on the meridian, above the pole, the bottom lies toward us, with the handle on the right.
Benetnasch is a bright star of the 2d magnitude, and is the first in the handle. The second, or middle star in the handle is Mizar, 7° distant from Benetnasch. It may be known by means of a very minute star almost touching it, called Alcor.
145. The third star in the handle is called Alioth, and is about 41° W. of Mizar. Alioth is very nearly opposite Shedir in Cassiopeia, and at an equal distance from the pole. Benetnasch, Mizar, and Alioth constitute the handle, while the next four in the square form the bowl of the Dipper.
146. Five and a half degrees W. of Alioth is the first star in the top of the Dipper, at the junction of the handle, called Megrez; it is the smallest and middle one of the cluster, and is used in various observations both on sea and land for important purposes.
When Megrez and Caph have the same altitude, and are seen in the same horizontal line east and west, the polar star is then at its greatest elongation from the true pole of the heavens; and this is the proper time for an observer to take its angle of elevation, in order to determine the latitude, and its azimuth or angle of declination, in order to determine the magnetic variation.
147. At the distance of 44° S. W. of Megrez is Phad, the first star in that part of the bottom which is next the handle.
The stars in this cluster are so well known, and may be so easily described without reference to their relative bearings, that they would rather confuse than assist the student, were they given with ever so much accuracy. The several bearings for this cluster were taken when Megrez was on the meridian, and will not apply at any other time, though their respective distances will remain the same.
148. At the distance of 8° W. of Phad, is the westernmost star in the bottom of the Dipper called Merak. The bright star 5° N. of it, toward the pole, is called Dubhe. These two, are, by common consent, called the Pointers, because they always point toward the pole; for, let the line which joins them be continued in the same direction 28° further, it will just reach the north pole.
The names, positions, and relative distances of the stars in this cluster should be well
144. How is the handle of the Dipper situated, when the Dipper is above the pole? Describe Benetnasch? Mizar? How known? 145. Alioth? Megrez? Remark respecting? Phad? Remark in small print? 148. Merak and Dubhe? Constitute what? Remark respecting the names, positions and distances of the stars in Ursa Major? Why should these distances be well understood?
remembered, as they will be frequently adverted to. The distance of Dubhe, or the Pointer nearest to the north pole, is 28%. The distance between the two upper stars in the Dipper is 10°; between the two lower ones is 8°; the distance from the brim to the bottom next the handle, is 4; between Megrez and Alioth, is 5°; between Alioth and Mizar, 4°; and between Mizar and Benetnasch, 7°.
The reason why it is important to have these distances clearly settled in the mind is, that these stars, being always in view, and more familiar than any other, the student will never fail to have a standard measure before him, which the eye can easily make use of in determining the distances between other stars.
149. The position of Megrez in Ursa Major, and of Caph in Cassiopeia, is somewhat remarkable. They are both in the equinoctial colure, almost exactly opposite each other, and equally distant from the pole. Caph is in the colure, which passes through the vernal equinox, and Megrez is in that which passes through the autumnal equinox. The latter passes the meridian at 9 o'clock, on the 10th of May, and the former just six months afterward, at the same hour, on the 10th of November.
150. Psi, in the left leg of Ursa Major, is a star of the 4th magnitude, in a line with Megrez and Phad, distant from the latter 121. A little out of the same line, 3° farther, is another star of the 4th magnitude, marked Epsilon, which may be distinguished from Psi, from its forming a straight line with the two Pointers.
151. The right fore-paw, and the two hinder ones, each about 15° from the other, are severally distinguished by two stars of the 4th magnitude, between 1° and 2° apart. These three duplicate stars are nearly in a right line, 20° S. of, and in a direction nearly parallel with Phad and Dubhe, and are the only stars in this constellation that ever set in this latitude.
There are a few other stars of equal brightness with those just described, but amidst the more splendid and interesting group with which they are clustered, they seldom engage our observation.
The whole number of visible stars in this constellation is 87; of which five are of the 2d, two of the 3d, and about twice as many of the 4th magnitude.
URSA MAJOR is said to be Calisto, or Helice, daughter of Lycaon, king of Arcadia. She was an attendant of Diana, and mother of Arcas, by Jupiter, who placed her among the constellations, after the jealousy of Juno had changed her into a bear.
"This said, her hand within her hair she wound,
149. What said of Megrez and Caph? 150. Of Psi and Epsilon?
151. How find
the feet of the figure? Number of stars in Ursa Major? Magnitudes?
HISTORY.-Who was Ursa Major before she became a bear? What other supposition? How are the two bears represented by the Egyptians? What further remarks ?