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this distance-one hundred and seventeen thousand years would thus be occupied; and, if you thought of travelling it at all, you would find that it could not be accomplished in seventy-four millions of years. Having thus ascended where the nearest of the fixed stars are, let us, in the next place, ascertain what they arewhether planets or suns, or what? We all know with how much facility we see a bright light, though it may be very small. A candle or taper can be seen in foggy weather long before the building containing it; and even in the case of reflected light, the merest spicula of glass, how brightly it shines, and how readily it can be distinguished from the dark substances surrounding it. The light of a star must be very intense, for even when highly magnified by a telescope, so that its light is enfeebled, it yet shines brightly, though appearing nearly as a mere point; and if the light of it is reflected light why do we not see the body that illuminates the star? What is that body? It cannot be the sun, because, even at the very moderate distance of the planets, it becomes very feeble; if, then, we could suppose the light coming from the stars to be reflected light, we would be at a loss to discover the luminous body that shines upon them. But it has been ascertained, by careful experiment, that the light of the very brightest fixed star, Sirius or the Dog star, which, if the night were clear, my audience might see as they passed out of the lecture room—we say it has been ascertained that the actual light emitted by this star, (with quite a probable allowance for distance, is full sixty-three times that of our sun; such is not always the case, as some stars do not give quite as much light as the sun. But it is true, notwithstanding, that if many of the stars are not suns they are more. It is unnecessary to contend about the name, for you must either call them suns or invent a name which shall mean a larger thing. When we make the statement that all the fixed stars are suns, are we aware of the sublimity involved in that statement ? I undertook to show my audience, as well as I could, a short time ago, what constituted a single sun; but it is also true that the tiny ray which gladdens our eye, as shooting from some twinkling star, it trembles in the casement; it is true that this is a miniature sunbeam, and the faint and feeble glow of starlight, which sometimes, like a semitransparent veil, covers the fair face of nature is woven of the scattered glory of thousands of suns. In the very fact that it is thus but faint and feeble we have the most speaking illustration of their awful distance; when we arrive at such a distance as this, it becomes quite evident that such a unit as the earth's distance from the sun is altogether too small. The distance of the earth from the sun must be taken some 500,000 times or more, in order to make a comparison, and we must therefore resort to something that will give us an adequate measuring unit. This may be found in the velocity of progression of the light which comes from the stars themselves. According to two different and independent results this velocity is about 192,000 miles per second ; the distance of the earth from the sun will thus be represented by 84 minutes. It takes a very trifle more than that for light to pass from the sun to the earth. The light comes from a Centauri, the nearest of the fixed stars, in 31 years; from 61 in the
Swan in 94 years; from Arcturus in 26 years; from the Polar star in 48 years; and from Capella in 704 years; or Capella, the beautiful star in the Goat, is seen by the light which left it nearly three-quarters of a century ago, and has been travelling at the rate of one hundred and oinety-two thousand miles per second during the whole of that interval.
Let us next notice the combinations of the stars. It is a very curious circumstance, to say the least, that wherever we direct the telescope to the heavens we shall find the stars combined in pairs ; and so frequently does this combination occur that we cannot regard it as the result of accidental position. It is true that when two stars are almost one behind the other they might not appear to be very far apart, though really at very different distances from us; but by careful measurement, in some cases, it has been ascertained that they are really, as well as apparently, near. In fact they are connected together, and revolve around each other, as is the case with the earth
We have here represented two or three such double stars. Toere is one in Gemini; also one in Scorpio, one of the two stars being blue and the other yellow. The blue star does not show well, unless in a very good light; but the representation is therefore the more true to nature, the sky being itself so blue that it is more difficult to see such a star. Red and yellow stars are also of frequent occurrence; and in the case of the beautiful star in Andromeda, the two individual stars are, the one rose color, and the other green; the colors of the double stars are complementary, or such as, when combined together, form a white light, the star appearing white and single to the bare eye. We can perceive something extremely elegant in the arrangement if planets should circulate around these red or green suns; then a red or a green light would be seen as long as it alone were visible; but a white light, when both suns were above the horizon, poetic fancy never sketched anything more sublimely elegant than this combination of tinted suns, these parti-colored gems which sparkle in the diadem which surrounds the dark brow of night.
We come now to a more extensive combination of stars. We cannot look at the sky with any sort of attention even once without perceiving an amazing collection of the stars in the direction of one single great band or girdle. This constitutes what is called the milky way. Throughout one half of its circuit it is divided into at least two parts. Most of the stars in heaven are situated in one part, and in the other portions of the sky the stars are comparatively sparse. The attempt was made by Sir William Herschel to ascertain the relative distance of the fixed stars before the actual distance of any of them was determined. Some idea may be formed of this by ascertaining how many more can be seen in one direction rather than another, as we might judge of the extent of a crowded audience in one direction rather than in another, by ascertaining how many could be seen in the one and in the other direction. A better method of sounding the heavens, as it was called, consisted in using successively telescopes of greater and greater space-penetrating power. The space-penetrating power may be ascertained by comparing the brightness of the beam of light emitted by a telescope with that seen by the bare eye. The science of optics will readily enable us to ascertain that. Then, if we dear in mind that light
at twice the distance is four times as feeble, &c., it will be seen that a telescope which would increase the intensity of light to four times that of the light seen by the bare eye might enable us to see twice as far, &c.
By making use of a telescope of a greater and greater space-penetrating power Sir William Herschel, in investigating portions of the milky way, continued to see new stars up to the twenty-eighth order of distance. The borders of the milky way are supposed to be at the nine hundredth order of distance. If this be so the time of the arrival of light from the borders of the milky way must not be measured by a single year, but by centuries; in fact, so far as we may rely on the conclusions of Dr. Mädler, the distance of the centre of this our group from us, as thus estimated, is 537 years. He concludes, moreover, that the stars in the milky way and our sun with them revolve at the rate of once in about eighteen million years. Whether we regard this as accurately ascertained or not, very certain it is that the sun and ell planets are moving in the regions of space.
The researches of Herschel, Argelander, Struve, and others, have all contributed to point out very accurately a single spot in the heavens, towards which we are incessantly travelling by a motion very slow when we consider the magnitude of the orbit, the distance travelled being about four-fifths of the diameter of the earth’s orbit every year.
When we scrutinize the outskirts of the milky way and attempt to see beyond it, we find what seems to be an entirely detached combination of stars. If what we see in them be stars only about the size of those in the milky way we might readily conclude that they were at no greater distance; but it may be that what are apparently single stars are themselves combinations. These groups are called clusters. This is the representation of a coarse cluster. We find others much more closely arranged, as in the figure, where they are represented by a white, powdery substance. The stars near the centre are not to be counted by hundreds. When clusters become so remote that you cannot make out the individual stars you may still discern ciusters of a granular shape and appearance in their structure; or that they are made up of a “star dust,” an expression sublime from its very simplicity. In this quasi crystalline mass the molecules are double stars, the ultimate particles are suns, and the atoms, if any, are planets. If the cluster be a globular one it may also be true that all the stars, the outer ones only excepted, are revolving around the centre in the self-same time. Beyond these still are the nebulæ, some of which the most powerful telescopes have failed to resolve; that is, have failed to show that they are made up of stars. In other cases they are found to be made up of stars, and resolvable. We cannot positively assert that there is no cloudy-looking substance existing in the heavens which is not made up in this way; some appearances, surrounding stars, cannot as yet be resolved. Other whole nebulæ cannot yet be resolved by telescopes of large space-penetrating power. Some idea of the distance of a nebula not resolvable may be obtained by ascertaining the space-penetrating power which will cause that nebula to present the appearance put on by another before power sufficient was applied to resolve it; and thus, comparing the powers employed in the two cases, we arrive at a distance so great as that & comparison by means of the velocity of light itself becomes almost
inadequate. Even light, (which could we thus curb its motion would girdle the earth in a twinkling,) which rebounds to us from the moon in a second and a quarter, and which, springing from its home in the sun, visits the most distant of the known planets and returns in less than a day, even this swiftly flying messenger, borne upon the very wings of the morning, can only reach us from those remote bounds after the lapse of centuries. Admitting all this to be true, then, although an accurate result is here no longer possible, there is a reasonable probability that the sublime idea presented by Huygens is itself a fact; that some of these bodies are so remote that the light by which we see them must have left them before the creation of man. There is something almost awful in the thought of our having arrived at a reasonable probability that we see these objects as they were before the race of man had being; to behold, as it were, the record of eternity past, unrolled to be read in time. We are compelled to view them from such a distance looking towards them; but in imagination we may place ourselves at the other extremity of the line thus defined, then the light from the earth and solar system would have been as long in reaching that position as the light from the other way has been in reaching us; and if we had the optical power and could look down upon the earth, then the mastodon, which is now a mere fossil in our cabinets, would be seen as the living, moving, breathing mastodon. The fact, in more general terms, is this: There are portions of the universe through which the visible record of very much that is great and awful that has been transacted here is still travelling through the regions of space, and might be discerned by a being provided with sufficient optical power. I think it necessary to notice but one thing more. The fixed stars are not merely like the sun in the intensity of their light, but, it would also seem, in revolving around their axes. We ascertain that the sun revolves around its axis by noticing the spots on its surface. When there are many spots towards us the light of the sun must be enfeebled, sometimes even sensibly so.
There are variable stars that periodically become dim and then again resume their former brightness. The natural solution of this fact is that these stars are like the sun, not merely in their light, but also in the way in which that light is produced. Perhaps upon their surface there are spots which, when turned towards us, cause their light to become dim, and when away from us there is an increase of brightness. There are stars also which may be called temporary stars; for after appearing in the heavens a brief period they become seemingly very small or they disappear altogether, a fact which can hardly well be accounted for, except by the supposition that there has been a real physical change in the body itself. In undergoing these changes, changes in color have also been manifest, so great that we may suppose that there has been a combustion or partial destruction of the body in question. The star seen by Anshelm in 1670 was of the third magnitude, passed through great fluctuations of light for two years, and then became either excessively small or quite invisible. There are, moreover, lost stars, whose places are now vacant, though some of them have been recently observed. When we look at these strange fluctuations we may suppose that something like combustion has taken place, or that, for the
time being, its power of giving light has been suspended. In reviewing these facts it appears difficult not to conclude that here was a world whose destiny was, for the time being, completed, and the fitful glare of whose gorgeous funeral pile shooting across almost the vast distance which separates us came with undiminished velocity to tell us the tale that once it was. However this may be, we certainly know that He who, “by His strength, setteth fast the mountains, being girded with power," hath also " of old laid the foundation of the earth, and the heavens are the work of his hands. They shall perish but He shall endure; yea, all of them shall wax old, like a garment, and as a vesture shall He change them, and they shall be changed; but He is the same and his years shall have no end;" for “He inhabiteth eternity and the praises thereof."