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have a volume vast enough, upon the lowest computation, to fill the whole orbit of Herschel !
In some instances a nebula presents the appearance of a faint, luminous atmosphere, of a circular form, and of large extent, surrounding a central star of considerable brilliancy. These are denominated Stellar Nebula.
The nebulæ furnish an inexhaustible field of speculation and conjecture. That by far the larger number of them consists of stars, there can be little doubt; and in the interminable range of system upon system, and firmament upon firmament, which we thus catch a glimpse of, the imagination is bewildered and lost. Sir William Herschel conjectured that the nebulæ might form the material out of which nature elaborated new suns and systems, or replenished the wasted light of older ones. But the little we know of the physical constitution of these sidereal masses, is altogether insufficient to warrant such a conclusion. (For a Spiral Nebula recently discovered by Lord Rosse, see Map IX., Fig. 68.)
VIA LACTEA (THE MILKY-WAY).
"Throughout the Galaxy's extended line,
Where every star that gilds the gloom of night
With the strong influence of a radiant sun."-Mrs. Carter.
256. THE VIA LACTEA, or Milky-Way, is that luminous zone or pathway of singular whiteness, varying from 4° to 20° in width, which passes quite around the heavens. The Greeks called it GALAXY, on account of its color and appearance: the Latins, for the same reason, called it VIA LACTEA, which, in our tongue, is Milky Way.
Of all the objects which the heavens exhibit to our view, this fills the mind with the most indescribable grandeur and amazement. When we consider what unnumbered millions of mighty suns compose this stupendous girdle, whose distance is so vast that the strongest telescope can hardly separate their mingled twilight into distinct specks, and that the most contiguous of any two of them may be as far asunder as our sun is from them, we fall as far short of adequate language to express our ideas of such immen. sity, as we do of instruments to measure its boundaries.
257. It is one of the achievements of astronomy that has resolved the Milky-Way into an infinite number of small stars, whose confused and feeble luster occasions that peculiar whiteness which we see in a clear evening, when the moon is absent. It is also a recent and well-accredited doctrine of astronomy,
the Nebula? Sir Wm. Herschel's conjecture? 256. What is the Via Lactea? Its Greek name? What said of its magnificence and grandeur? 257. What said of the achievements of astronomy? Its doctrine respecting the structure of the universe? Of the sun, and its relation to the fixed stars?
that all the stars in the universe are arranged into clusters, or groups, which are called NEBULE or STARRY SYSTEMS, each of which consists of myriads of stars.
The fixed star which we call OUR SUN, belongs, it is said, to that extensive nebula, the Milky-Way; and although apparently at such an inmeasurable distance from its fellows is, doubtless, as near to any one of them, as they are to one another.
258. Of the number and economy of the stars which compose this group, we have very little exact knowledge. Dr. Herschel informs us that, with his best glasses, he saw and counted 588 stars in a single spot, without moving his telescope; and as the gradual motion of the earth carried these out of view and introduced others successively in their places, while he kept his telescope steadily fixed to one point, "there passed over his field of vision, in the space of one quarter of an hour, no lest than one hundred and sixteen thousand stars, and at another time, in forty-one minutes, no less than two hundred and fifty-eight thousand."
In all parts of the Milky-Way he found the stars unequally dispersed, and appearing to arrange themselves into separate clusters. In the small space for example, between Beta and Sad'r, in Cygni, the stars seem to be clustering in two divisions; each division containing upwards of one hundred and sixty-five thousand stars. At other observations, when examining a section of the Milky-Way, not apparently more than a yard in breadth, and six in length, he discovered fifty thousand stars, large enough to be distinctly counted; and he suspected twice as many more, which, for want of sufficient light in his telescope, he saw only now and then.
259. It appears from numerous observations, that various changes are taking place among the nebula-that several nebulæ are formed by the disolution of larger ones, and that many nebulæ of this kind are at present detaching themselves from the Milky-Way. In that part of it which is in the body of Scorpio, there is a large opening, about 4° broad, almost desti tute of stars. These changes seem to indicate that mighty movements and vast operations are continually going on in the distant regions of the universe, upon a scale of magnitude and grandeur which baffles the human understanding.
More than two thousand five hundred nebulæ have already been observed; and, if each of them contains as many stars as the Milky-Way, several hundreds of millions of stars must exist, even within that portion of the heavens which lies open to our observation.
"O what a confluence of ethereal fires.
From urns unnumber'd down the steep of heaven
260. Although the Milky-Way is more or less visible at all seasons of the year, yet it is seen to the best advantage during
258. Number and economy of the stars? Dr. Herschel's statements? What number passed the field of his instrument in a quarter of an hour? In forty-one minutes? In space apparently only a yard in breadth? 259. What changes observed in the nebuWhat do they indicate ? Number of nebula? Estimated number of stars? 260. When is the Via Lactea seen to the best advantage? Direction when Lyra is on the
the months of July, August, September, and October. When Lyra is on, or near the meridian, it may be seen stretching obliquely over the heavens from northeast to southwest, gradually moving over the firmament in common with other constellations. (For views of our cluster, see Map IX., Figs. 69, 70, 71.)
Its form, breadth and appearance are various, in different parts of its course. In some places it is dense and luminous; in others, it is scattered and faint. Its breadth is often not more than five degrees; though sometimes it is ten or fifteen degrees, and even twenty. In some places it assumes a double path, but for the most part it is single.
It may be traced in the heavens, beginning near the head of Cepheus, about 30° from the north pole, through the constellations Cassiopeia, Perseus, Auriga, and part of Crion and the feet of Gemini, where it crosses the Zodiac; thence over the equinoctial into the southern hemisphere, through Monoceros, and the middle of the ship Argo, where it is most luminous, Charles' Oak, the Cross, the feet of the Centaur, and the Altar. Here it is divided into two branches, as it passes over the Zodiac again into the northern hemisphere. One branch runs through the tail of Scorpio, the bow of Sagittarius, the shield of Sobieski, the feet of Antinous, Aquila, Delphinus, the Arrow and the Swan. The other branch passes through the upper part of the tail of Scorpio, the side of Serpentarius, Taurus Poniatowskii, the Goose and the neck of the Swan, where it again unites with the other branch, and passes on to the head of Cepheus, the place of its beginning.
Some of the pagan philosophers maintained that the Milky-Way was formerly the sun's path, and that its present luminous appearance is the track which its scattered beams left visible in the heavens.
The ancient poets, and even philosophers, speak of the Galaxy, or Milky-Way, as the path which their deities used in the heavens, and which led directly to the throne of Jupiter. Thus, Ovid, in his Metamorphoses, Book i. :
"A way there is in heaven's extended plain,
The groundwork is of stars, through which the road
Milton alludes to this in the following lines :
A broad and ample road, whose dust is gold,
ORIGIN OF THE CONSTELLATIONS.
261. THE science of astronomy was cultivated by the immediate descendants of Adam. JOSEPHUS informs us that the sons of SETH employed themselves in the study of astronomy; and that they wrote their observations upon two pillars, one of brick
meridian? Its form, breadth, &c.? How traced in the heavens? Notion of the Pagan philosophers! Of the poets? What citations? 261. How early was astronomy cultivated?
and the other of stone,* in order to preserve them against the destruction which ADAM had foretold should come upon the earth.
He also relates, that Abraham argued the unity and power of God, from the orderly course of things both at sea and land, in their times and seasons, and from his observations upon the motions and influences of the sun, moon and stars; and that he read lectures in astronomy and arithmetic to the Egyptians, of which they understood nothing till Abraham brought these sciences from Chaldea to Egypt; from whence they passed to the Greeks.
262. BEROSUS also observes that Abraham was a great and just man, and famous for his celestial observations; the making of which was thought to be so necessary to the human welfare, that he assigns it as the principal reason of the Almighty's prolonging the life of man.
This ancient historian tells us, in his account of the longevity of the antediluvians, that Providence found it necessary to prolong man's days, in order to promote the study and advancement of virtue, and the improvement of geometry and astronomy, which required, at least, six hundred years for making and perfecting observations.t
263. When Alexander took Babylon, Calisthenes found that the most ancient observations existing on record in that city, were made by the Chaldeans about 1903 years before that period, which carries us back to the time of the dispersion of mankind by the confusion of tongues. It was 1500 years after this that the Babylonians sent to Hezekiah, to inquire about the shadow's going back on the dial of Ahaz.
It is, therefore, very probable that the Chaldeans and Egyptians were the original inventors of astronomy; but at what period of the world they marked out the heavens into constellations, remains in uncertainty. La Place fixes the date thirteen or fourteen hundred years before the Christian era, since it was about this period that Eudoxus constructed the first celestial sphere upon which the constellations were delineated. Isaac Newton was of opinion, that all the old constellations related to the Argonautic expedition, and that they were invented to commemorate the heroes and events of that memorable enterprise. It should be remarked, however, that while none of the ancient constellations refer to transactions of a later date, yet we have various accounts of them of a much higher antiquity than that event.
264. Some of the most learned antiquarians of Europe have searched every page of heathen mythology, and ransacked all the legends of poetry and fable for the purpose of rescuing this subject from that impermeable mist which rests upon it, and they have only been able to assure us, in general terms, that they are Chaldean or Egyptian hieroglyphics, intended to perpetuate, by means of an imperishable record, the memory of the times in which their inventors lived, their religion and manners,
*Josephus affirms, that "he saw himself that of stone to remain in Syria in his own time." + Vince's Complete System of Astronomy, Vol. ii. p. 244.
262. What further proof? What reason 263. What discovery by Calisthenes?
What proof? What said of Abraham? assigned for the longevity of the antediluvians?
What conclusion from this discovery? La Place's date of the origin of the constella tions? Sir Isaac Newton's opinion? Remark? results?
264. What researches, and what
their achievements in the arts, and whatever in their history was most worthy of being commemorated. There was, at least, a moral grandeur in this idea; for an event thus registered, a custom thus canonized, or thus enrolled among the stars, must needs survive all other traditions of men, and stand forth in perpetual characters to the end of time.
265. In arranging the constellations of the Zodiac, for instance, it would be natural for them, we may imagine, to represent those stars which rose with the sun in the spring of the year, by such animals as the shepherds held in the greatest esteem at that season; accordingly, we find Aries, Taurus, and Gemini, as the symbols of March, April, and May.
266. When the sun enters the sign Cancer, at the summer solstice, he discontinues his progress towards the north pole, and begins to return towards the south pole. This retrograde motion was fitly represented by a Crab, which is said to go backward. The sun enters this sign about the 22d of June.
The heat which usually follows in the next month was represented by the Lion; an animal remarkable for its fierceness, and which at this season was frequently impelled by thirst to leave the sandy desert, and make its appearance on the banks of the Nile.
267. The sun entered the sixth sign about the time of harvest, which season was therefore represented by a Virgin, or female reaper, with an ear of corn in her hand.
At the autumnal equinox, when the sun enters Libra, the days and nights are equal all over the world, and seem to observe an equilibrium or balance. The sign was therefore represented under the symbol of a pair of Scales.
268. Autumn, which produces fruit in great abundance, brings with it a variety of diseases, and on this account was represented by that venomous animal, the Scorpion, which, as he recedes, wounds with a sting in his tail. The fall of the leaf, was the season for hunting, and the stars which mark the sun's path at this time were represented by a huntsman, or archer, with his arrows and weapons of destruction.
The Goat, which delights in climbing and ascending some mountain or precipice, is the emblem of the winter solstice, when the sun begins to ascend from the southern tropic, and gradually to increase in height for the ensuing half year.
266. Of Cancer and Leo? 267. Of
265. Origin of Aries, Taurus, and Gemini ? Virgo and Libra? 268. Of Scorpio and Capricorn?