The fairy tales of science/A Flight through Space

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The fairy tales of science by John Cargill Brough
A Flight through Space
"A Flight through Space"

A Flight through Space.

"We fly by night."—Macbeth.

Let us take our station, on a clear evening, in some wide, open plain, and gaze upward and around on the star-spangled heavens that shroud and reveal—reveal and shroud—the unfathomable mystery of the Infinite and Eternal. Though from the spot we occupy in space we can see only a small portion of the visible universe, yet even with the naked eye we behold a multitude of bright luminaries. As we continue to watch them we find that the immense majority of them shine with a twinkling light, and retain the same relative position to each other, whilst the remainder, very few in number, shed a steady light, and change their places continually, returning at given periods in the same path. We are thus led to divide the heavenly bodies within the sphere of our perception into two principal classes or systems—the sidereal—as we will call it here, for convenience' sake—and the planetary. The stars belonging to the former are popularly called fixed stars, although this term, in its strictest acceptation, must be held not to be quite applicable to them, as they unquestionably have measurable motions of their own. Those belonging to the latter are called erratic or wandering stars, popularly planets, from a Greek word signifying a wanderer; these include the sun, moon, our own earth, and the other planetary bodies, as well as the comets. The erratic stars constitute, with the sun—about which they move as their common centre or focus, in obedience to the great universal law of gravitation revealed to us by the genius of Newton and his sublime predecessor the illustrious Kepler—the solar system, which, however so infinitesimally small in comparison to the infinite magnitude and extent of the sidereal world, men must naturally regard with greater and more vivid—nay, if the expression may be permitted us, with more affectionate—interest than the universe beyond. Moreover, the bodies composing this system are comparatively near to us, and more within the reach of our observation, than the fixed stars, which are placed at immeasurable distances from us. Let us, therefore, first take, as we are being wafted on with our planet through space, a rapid survey of them, before proceeding to the contemplation of the “world of worlds” beyond.

By a long series of patient observations of a most delicate kind, aided by the telescope and other marvellous instruments devised by human ingenuity, and by refined combinations of theoretical reasoning and logical induction, man has succeeded in measuring the dimensions, gauging as it were the contents, and weighing as in a balance the mass, not of our earth alone, but of all the other planets, and of the great sun himself.

Thus we know that the equatorial diameter of our globe is about 7926, the polar diameter 7900 miles; that our earth revolves round its axis with a velocity of nearly 12 miles in a minute, and that it moves in its orbit round the sun at a rate of more than 1000 miles a minute; that its distance from the sun is 95,000,000 miles.

The moon, the satellite of the Earth, is distant from it some 240,000 miles, and revolves round it in 27 1/2 days; its diameter measures only 2180 miles.

Of the other planetary bodies, some are considerably larger, some smaller, than our earth. The largest of all, the brightest among them, is Jupiter, with a diameter of about 88,000 miles, and a bulk 1300 times that of the Earth; owing to his inferior density, his mass is, however, only upwards of 370 times that of our globe. Perpetual spring reigns on this King of Planets. Jupiter is attended by four satellites or moons, with the exception of one, each of them larger than our moon, which revolve round him from west to east. His distance from the sun is 485,000,000 miles; his revolution round the great centre of the planetary world occupies 12 years. The next in size is Saturn, with a diameter of 79,000 miles, and accordingly about 1000 times larger than the Earth; he is 890,000,000 miles distant from the sun, and revolves round it in 29 years. A revolving luminous ring, consisting of three distinct portions, one within the other, surrounds this most remarkable planet, and eight satellites revolve round him. Uranus was, up to Adams’s, Leverrier’s, and Galle’s recent discovery of Neptune, considered the most distant planet from the solar centre of the system; the distance being calculated at 1,800,000,000 miles, and the period of revolution, 84 years. The diameter of Uranus is 35,000 miles, and the bulk about 80, the mass about 20, times that of the Earth; at least four satellites are known to revolve round him, and several more undoubtedly exist. Neptune, now the most distant known planet from the sun (2,800,000,000 miles), revolves round the latter in 165 years; the diameter of this planet is 37,500 miles, the bulk about 107 times that of the Earth, the mass about the same as that of Uranus. Among the lesser planets, we have to mention Mercury, the one nearest the solar centre, being distant from it only 37,000,000 miles; the period of his revolution is 88 days. His diameter is about 3200 miles; from the close proximity of this planet to the sun, it is conjectured that the mean heat in it is above that of boiling quicksilver, and even near the poles water would always boil. Its mass is about one-twelfth that of the Earth, the mean density rather greater than that of our planet. Venus, next to Jupiter the brightest and most important and interesting of the planets, has a diameter of about 7800 miles; some 68,000,000 miles distant from the centre of the solar system, she revolves round it in 224 days. Nearly of equal size, mass, and density as the Earth, and with a comparatively trifling difference of some 27,000,000 miles between the respective distances of the two planets from the sun, Venus would be supposed to present the same climatological and meteorological conditions as her sister planet; and this would unquestionably be the case, but that Venus happens to turn most obliquely round her axis, whence it results that snow and ice cannot accumulate at the poles, which are subjected by turns for some four months to the fierce glare of an almost vertical sun, and that there are no temperate zones in that planet as in ours; though an atmosphere, much loaded with clouds, would certainly seem to mitigate in some measure the intense glare and heat of the sunshine.

Mars, the nearest of the superior planets exterior to the Earth, presents more points of similarity to the latter than any of the other. His diameter is about 4100 miles, his distance from the solar centre, round which he revolves in 687 days, 142,000,000 miles; his mass is about one-seventh part of that of the Earth, and his density a trifle smaller. He is evidently surrounded by an atmosphere of considerable density; he shines with a red and fiery light; seen through a good telescope, his disk presents something like a vague delineation of seas and continents. Near the poles a zone of white is seen, clearly denoting the existence of large masses of snow. The climate of this planet must be considerably colder than ours; but, from the similar obliquity of the ecliptic, and almost identical period of diurnal rotation of the two, the changes of the seasons must be very similar to our own, though with much greater variations.

Besides these larger planets, there are found between Mars and Jupiter about thirty smaller planets and asteroids, most of them exceedingly minute, and discernible only through the telescope. Vesta and Pallas are the brightest among them, and may, when nearest to us, be just barely detected with the naked eye, though even then with the greatest difficulty only.

To convey to the mind of the reader an intelligible general impression of the relative magnitudes and distances of the principal parts of the planetary system, let a globe two feet in diameter be placed on a well levelled field, to represent the Sun. Mercury will then be represented by a grain of mustard-seed on the circumference of a circle 164 feet in diameter for its orbit. Venus will appear as a pea, on a circle 284 feet in diameter; the Earth of the same size, on a circle of 430 feet; Mars of the size of a rather large pin’s head, on a circle of 654 feet; Juno, Ceres, Vesta, and Pallas, grains of sand, in orbits of from 1000 to 1200 feet; Jupiter a moderate-sized orange, on a circle about 720 yards across; Saturn a smaller orange, on a circle of four-fifths of a mile; Uranus a small plum, on the circumference of a circle above a mile and a half in diameter; Neptune a somewhat larger plum, on the circumference of a circle about two miles and a third in diameter.

Having thus briefly glanced at the planetary satellites of the sun, we will now proceed to view, with equal briefness, that great centre of the system itself, which feeds and vivifies them all with its glorious rays. The stupendous globe which we call the sun, is about 1,400,000 times as large as our earth, its diameter being 885,000 miles! However, its density being only 0·2543 as compared to that of the earth, it contains only 354,936 times the mass or quantity of ponderable matter that the latter consists of. It turns on its axis in 25 1/4 days, as proved by telescopic observations of certain dark spots on its surface. The sun apparently moves round the earth, though it is in reality the latter body which moves round the sun, in a nearly circular orbit, described in a plane, sensibly fixed, called the ecliptic. The ancients called that portion of the heavens in which the sun’s apparent orbit is performed the zodiac, and divided the great circle formed by the intersection of the plane of this orbit with the sphere of the heavens into twelve equal portions or signs, named in order—Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, Aquarius, Pisces. The sun, however, has also a real motion: he moves with the entire solar system in the direction of the constellation of Hercules in the western sky. The sun’s rays are the ultimate source of all the motions observed on the surface of our planet, and of all vegetable and animal life on it; since it is by their vivifying action that plants are elaborated from inorganic matter, to become in their turn the support of animals and of man, and the source of our great coal deposits, so felicitously and truly called by the late George Stephenson “bottled sunshine!” By the unequal action of the solar heat are produced all winds and storms, and those disturbances in the electric equilibrium of the atmosphere which give rise to the phenomena of terrestrial magnetism. By the solar rays the waters of the sea are drawn up into the air in vapour, to descend again in rain, irrigating and fertilizing the land, and producing springs and rivers. To their action and influence must mainly and primarily be attributed the chemical compositions and decompositions of the elements of nature, nay, even the phenomena of volcanic activity.

Judging by what we see around us on our own globe, and by the way in which every corner of it is crowded with living beings, and arguing from the most natural of all analogies, most, if not all, of the other larger planets of our solar system must be held to be habitable and inhabited worlds like our earth.

By nations in the infancy of intellectual development the heavens above and around us might have been looked upon as a kind of solid arch, vault, or canopy, hung with greater and lesser lamps, intended solely for the special behoof and benefit of the puny dwellers on this puny atom which we call our earth. But we of a generation immeasurably more advanced in knowledge, to whom the beneficence of the Creator has deigned to unclasp the first volume of the great Book of Nature, that we may read the marvellous page, and bow down and adore the Infinite Wisdom that conceived, the Infinite Power that made this glorious world; we, who are permitted to walk in the light of knowledge and science, before which the desponding comment of “Athena’s wisest son” upon human knowledge, that

All we know is—nothing can be known,”

stands rebuked and disproved; we who may span with a thought the inconceivable distance which separates our planet from the “threshold of space”—we can no longer entertain the same crude and “unintelligent” notion of the “nature and purpose” of the works of the Divine Hand.

The discoveries of science have disclosed to us in each planet, which, like our own, revolves in regulated periods round the sun, provisions in all respects similar to those found to exist here:—the same structure, form, and materials—the same action and influence of the same calorific and illuminating agency—the same alternations of light and darkness, produced by the same means—the same pleasing succession of seasons—the same diversity of climate—the same agreeable distribution of land and water.

With the overwhelming evidence of these most essential analogies between our own and the other planets before our mind, how can we doubt but that those other “celestial structures” have been made, provided, and fitted by God to be the abodes of sentient beings kindred to the denizens of our earth? As direct evidence of the fact, however, remains as yet still denied us, attempts have not been, and even now are not wanting to throw doubt on the correctness of this inference from our analogical reasoning. But most of the “arguments” adduced against the supposition of the planets being inhabitable globes like our earth are of too flimsy and futile a nature to be deserving even of a passing allusion; others have been convincingly refuted. Thus, to give an instance, it has been advanced that Jupiter, Saturn, Uranus, and Neptune, being severally five, nine, eighteen, and twenty-eight times farther removed from the sun than our earth, the heating and illuminating power of the solar rays must be in these large planets respectively 25, 81, 324, and 784 times less than on our globe, which would preclude the possibility of the existence on them of beings organized like the denizens of earth. The simple consideration, however, that a mere enlargement of the pupil of the eye in the ratio of the diminution of the apparent superficial magnitude of the sun’s disk as respectively beheld from these planets, or a proportionally increased sensibility of the retina, would leave the illuminating power of the sun the same as at the earth; and that in like manner the diminished calorific power of the solar rays might be compensated by modified atmospheric conditions, will suffice to dispose of this objection. The only tenable argument against the habitableness of those large globes might be, that from their vast magnitude in comparison to the earth the effects of gravity upon them would be such as to unfit species organized like those of the latter for existence there, since they would, in fact, be crushed to pieces under the enormous pressure of their own weight. But leaving out of consideration the very obvious expedient of a proportionate adaptation of the size and weight of the bodies placed upon these globes to the respective magnitudes of the latter, a more careful examination of the question, and application of the rule, that “the weight of bodies placed upon the surface of a globe depends conjointly on the quantity of matter in the globe, and on the distance of the body from its centre,” will at once show that owing to the inferior density of the matter composing the four large planets, which in comparison to that of the matter composing the Earth, is for Jupiter as 1 to 4, for Saturn as 1 to 8 1/2, for Uranus and Neptune as 1 to 6; the weight of bodies placed on the surfaces of the three latter planets actually does not differ much from their weight on the earth, whilst in the case of Jupiter, it is only 2 3/4 times greater than upon the terrestrial globe.

In the case of the moon we are led to believe from the desolate bleakness of her surface, and the total absence of all indications of an atmosphere, that she is not inhabited by organized beings. But even here, how know we but that that most beneficent emanation of the “self-evolving energy divine,” that most powerful agent in the mysterious chemistry of the spheres—the all-vivifying rays of the sun, may not be silently at work re-fitting even that “cinder of an extinct world,” for the habitation of kindred beings?

The satellites of the other planets have been proved by astronomical observation to be under physical conditions similar to that of the moon; and it is probable, therefore, that they are at all events not as yet in a proper state of habitability. Finally, as regards the planetoids or asteroids—whether we look upon them in the light of fragments of a smashed or exploded planet, or in that of germs or constituent elements of a future planet in process of formation by coalescing and agglomeration—it is plain that they present none of the leading and essential analogies to our earth that are observed in the larger planets.

To those “strange wanderers of the sky,” comets, we intend to devote a separate chapter, and will therefore now at once wing our flight beyond the narrow limits of our solar system, to the confines of the visible universe—to the threshold of the abyss of space beyond.

The innumerable multitude of celestial bodies, which seemingly preserve from age to age the same relative situation in the heavens, and are therefore popularly called “fixed stars” (although, as we have already taken occasion to observe, they have unquestionably all of them measurable motions of their own, too slow, indeed, to be sensibly perceptible, yet none the less real), were classified by the ancients into fanciful groups, called constellations, to which names were assigned, either from some supposed resemblance of the outlines of the group to figures of men, animals, or other objects—for example, Ursa Major, Ursa Minor, Draco, Aquila, Cygnus, Serpens; the names of the signs of the zodiac, which we have already given; Lyra, &c.; or by way of a special tribute of veneration to some departed hero or heroine—e.g., Hercules, Perseus, Andromeda, Cassiopeia, &c.; or from the most grovelling adulation—of which the name of Coma Berenices, bestowed upon a constellation above Leo, affords a most striking instance. Berenice, daughter of Magas of Gyrene, and wife of Ptolemy III., King of Egypt, rejoiced in an abundance of very beautiful hair, of which she was inordinately vain; a portion of this had been suspended in a temple, from which it was suddenly missed one day—to the great consternation of the courtiers, who had reason to dread the anger of the “bereaved” beauty. However, Conon the astronomer, a sharp fellow in his way, luckily bethought himself of the notable expedient of looking for the missing locks in the heavens, where, sure enough, he beheld them quite plain, the same having been “translated” to that exalted position by the gods, evidently on account of their surpassing loveliness. The laureate of the Egyptian court, Callimachus, wrote a poem thereon. The “delicate” flattery succeeded to the fullest extent; the queen was more than satisfied, and the Coma Berenices shines down on us to the present day! The catalogue of stars which forms part of the famous Almagest of Ptolemy of Alexandria,[1] an astronomer who flourished in the second century after Christ, contains 1022 stars, arranged in forty-eight such constellations. Although these fanciful divisions and classifications of the stars are altogether lacking a scientific or other practical and intelligible basis, and would seem, as Sir John Herschel truly and pertinently observes, to have been purposely named and delineated to cause as much confusion as possible, yet the general convenience which they afford is so great, and the stars have in process of time become so intensely identified with their names, that they have for ages been permitted, and must even in our own days still be permitted, to retain them.

A much more rational division of the stars, however, is that into classes, according to their apparent brightness. These classes astronomers term magnitudes. The brightest stars are said to be of the first magnitude; those next in brightness of the second magnitude, and so forth. The stars down to the sixth magnitude are visible to the naked eye; it requires, however, tolerably good eyes to distinguish those of the sixth magnitude, even on very clear evenings. For stars below the sixth magnitude we must have recourse to telescopes; with the aid of the most powerful of these instruments, we can at present discern stars down to the twentieth magnitude, and even below. The number of stars of the first magnitude is very small, only about 20 of them being counted in the heavens; those of the second magnitude number 65; of the third, 190; of the fourth, 425; of the fifth, 1100; of the sixth, 3200; of the seventh, 13,000; of the eighth, 40,000; of the ninth, 142,000,—which gives a total number of 200,000 stars down to the ninth magnitude. As a glance at these figures will show, the numbers increase very rapidly as we descend in the scale of brightness. To conceive a notion, still most inadequate, however, of the countless multitudes of stars that are dispersed through infinite space, we need simply reflect that Sir William Herschel, through his powerful telescope, discovered some eighteen millions of stars, of an average magnitude between the tenth and eleventh, in the milky way alone—that great luminous band which stretches all across the sky from horizon to horizon. What inconceivable numbers should we arrive at, were we to go down to the twentieth magnitude! or attempt to count the myriads of star-clusters composing those "clouds of suns" that are comprehended under the general name of nebulæ [2] and of which Sir William and Sir John Herschel have catalogued above 4000! What an inexhaustible field of speculation and conjecture is opened here to the imagination! The finite mind of man, with its limited comprehensive powers, is bewildered and lost in the interminable range of system upon system, firmament upon firmament, of stars, each of them a sun, and probably in its sphere the presiding centre round which planetary worlds may be revolving, the dwelling-places, perchance, of intelligences of an immeasurably superior order to ours.

The classification of stars into magnitudes by estimation of their relative brightness, although unquestionably much more rational than the unmeaning division into constellations, is, however, entirely arbitrary. As we can only judge of the brightness of a star by the total impression made by its light upon the eye, it is quite evident that the assumed magnitude will depend, first, on its distance from us; second, on the absolute extent of its illuminated surface; third, on the intrinsic brightness of that surface;—and of these data we know nothing, or next to nothing. Up to a recent period we only knew that the nearest fixed stars could not possibly be placed at a distance so small as 19,200,000,000,000 miles from the sun; but certain most admirable observations and measurings, made by the illustrious Bessel, have since clearly established the astounding fact that the fixed stars placed nearest to our solar system are distant from it some 57,000,000,000,000 miles—a distance utterly inconceivable by the human mind. Light travelling, as is well known, at the rate of 192,000 miles per second, it will take a ray from the fixed stars nearest to us some 9 1/3 years to reach the earth! But if this nearest and comparatively trifling distance is sufficient to appal the human understanding, what shall we say or think of the immeasurably greater distances which separate us from the remoter stars, and from the most distant visible nebulæ, whose light, it has been calculated, will take at least a million years to reach our earth! To arrive at some approximate estimation of the real magnitude of the stars, the light which they shed on us, and the most imperfect and as yet still almost entirely negative knowledge which we have obtained respecting their distances, must be our only guide. Now, direct photometrical[3] experiments have shown that the light of Sirius, the most brilliant of the fixed stars, is, at equal distances, 146 1/2 times more intense than that of our Sun, and that it would accordingly require a collection of more than 146 suns to shed a ray of light on our earth like that of Sirius, supposing the two bodies to be placed at the same distance from us.[4]

Several among the stars exhibit the most remarkable phenomenon of a regular periodical increase and diminution of lustre, involving, in some rare instances, an alternate total extinction and revival. These are called periodical, or variable stars. One of the most remarkable is the star Omicron, in the constellation Cetus, which has a period of 334 days. It remains about a fortnight at its greatest brightness, equal to a large star of the second magnitude; it then decreases during about three months until it disappears altogether; after remaining invisible during about five months, it reappears again, and continues increasing in brilliancy during the remaining three months of its period. It shows, however, occasionally considerable irregularity in its phases, and has actually been known on one occasion to remain altogether invisible during more than four years (between October, 1672, and December, 1676). Another remarkable specimen of a variable star is Beta, in the constellation of Perseus. The whole period of change of this star is rather less than 2 days 20 hours and 49 minutes, during which time it varies in brightness from the second magnitude to the fourth; its changes are confined, however, to a few hours, as it continues for rather more than 2 days 12 hours at its state of greatest brightness.

Stars have also occasionally appeared suddenly in various parts of the heavens, blazing forth for a time with extraordinary lustre, and after remaining awhile apparently immovable, have gradually decreased in brightness, and finally altogether vanished. These are properly termed temporary stars. Thus there suddenly appeared in the time of Tycho Brahe, (1572, 11th November), in the constellation of Cassiopeia, a most lustrous star, equalling Sirius in brightness; it continued increasing in brilliancy up to December, 1572, when it actually surpassed Jupiter and Venus when nearest to the earth, and was visible at mid-day. From this period forward it began to diminish rapidly, and in March, 1574, it had completely disappeared from the heavens. Another equally brilliant star burst forth on the 10th October, 1604, in the constellation of Serpentarius, and continued visible till October, 1605. The fact of the sudden appearance and subsequent disappearance of such temporary stars affords an irrefragable indication that there must exist also in space immense dark bodies, absolutely invisible to us, and of which accordingly we cannot possibly have any knowledge, as light is the only means of communication between the stars and the earth.

There remains now for us still to consider another marvel of the heavens—the double and multiple stars. The telescope has revealed to us that several thousands of stars which appear single to the naked eye, consist in reality of two or more luminous bodies placed in close proximity to each other; the observations, and researches made principally by Sir William and Sir John Herschel, Sir James South, and the great Russian astronomer Struve, have placed it beyond doubt that the proximity of these stars to each other is by no means accidental, but that they are physically connected together by the tie of gravity, and revolve round each other as the planets do round the sun, and in obedience to the same law of attraction and gravitation which governs the motions of the solar system. Many of the double stars of unequal magnitude exhibit the beautiful phenomenon of complementary colours. Thus, if the larger star be of a ruddy or orange hue, the smaller one will appear blue or green; if the larger star appear yellow, the smaller will appear blue; if the light of the brighter star incline to crimson, that of the other will incline to green. In connexion with this subject we may here remark, that in many parts of the heavens isolated stars have been observed of a red colour, almost as deep as blood.

Thus, Arcturus, Aldebaran (in Taurus), Antares (in the Scorpion), are red stars; and what is more curious still, Sirius, whose light is now, and has been for several centuries, of the purest white, is mentioned by Ptolemy and all other astronomers of antiquity as a red star. Lyra, Cygnus, Cor Leonis, Virgo, are white stars. 'Canis Minor, Aquila, the Polar Star, and the star Beta, in Ursa Minor, shed a yellow light. In certain nebulae all the suns are of the same colour, blue for instance; whilst in the nebulæ of Lacaille, near the Southern Cross, powerful telescopes reveal to the delighted eye. more than a hundred differently coloured stars—red, green, blue, and of a greenish blue.

Thus far have we winged our daring flight to the utmost confines of the visible heavens, to the Ultima Thule of the starry world. But beyond, into the endless realms of space, we may not soar. Here Almighty wisdom has fixed a barrier, sealed to the finite intellect of man. The superior intelligences of higher spheres may perchance pass beyond into the immensity of God’s creation, to stand in their turn on the confines of another immensity, into which even they may not enter—and so on in endless succession.

Verily, verily, inconceivable and ineffable is the magnitude of the works of the Almighty. A flight through space? No, no, not through space; ay, not even yet towards the threshold of space!

  1. This catalogue of stars is generally held to be the most ancient on record. However, this is a popular error. An earlier catalogue had been drawn up, about 125 B.C., by the illustrious Hipparchus, the greatest astronomer of antiquity, and, indeed, up to the days of the immortal Kepler. The catalogue of Hipparchus supplied the materials from which Ptolemy compiled his. At present there are some 130,000 stars catalogued!
  2. Sir William Herschel was enabled, by the powers of his large reflecting telescope, to divide and arrange the nebulous masses of light discovered by him in his general sweep of the northern heavens into the following six classes: —1st. Distinct clusters of separate stars; 2nd. Resolvable nebulæ, or such as, though not distinctly resolved, yet clearly indicated that their resolution might be accomplished by more powerful optical instruments. Most of these have indeed now yielded to the powers of Lord Rosse's gigantic six-feet reflector; 3rd. Nebulæ showing no trace of resolution in his (Sir William Herschel's) telescope. In some of these, also, separate stars have been detected by Lord Rosse's telescope, and by the great refractor of the observatory at Cambridge, near Boston, United States; and with every new increase in the dimensions and power of our optical instruments, we may expect to see these "clouds of light" more and more resolved into myriads upon myriads of separate stars; 4th. Planetary nebulæ, or such as have the appearance of planets; 5th. Stellar nebulæ; and, 6th. Nebulous stars, which, according to Sir John Herschel's definition, consist of "a sharp and brilliant star, concentrically surrounded by a perfectly circular disk or atmosphere of faint light, in some cases dying away insensibly on all sides, in others almost suddenly terminated." This may also be the proper place to make a passing allusion to two most remarkable phenomena visible with the naked eye in southern latitudes, called the Magellanic Clouds. They are "two cloudy masses of light of a somewhat oval shape. When examined through powerful telescopes, they are found to be of astonishing complexity of constitution, the general ground of them consisting of large tracts and patches of nebulosity in every stage of resolution, and of clustering groups, interspersed with numerous nebulae, globular clusters in every stage of condensation, and objects of a nebulous character quite peculiar, and having no analogy in any other part of the heavens.”
  3. Light-measuring.
  4. To realize, however so feebly, the idea of the magnitude and intense luminousness of Sirius, we need simply reflect that the diameter of the sun is 885,000 miles, and that the light of the latter is about 800,000 times more intense and brilliant than that of the full moon.