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from the source indicated. So that sev- weather prevented any observations beeral days or so before details of the dis- ing made there. covery reached Europe, the present wri- The first news was expressed in teleter communicated it to the Times (in a graph-language, and was imperfect. It letter which appeared on Saturday, Au

ran thus: Two satellites of Mars disgust 25), or less than a week after the covered by Hall at Washington. First second moon had been detected, as a elongation west August 18, eleven hours, discovery not open to doubt or question. Washington time. Distance eighty sec

Within two days from this, or on Au- onds. Period, thirty hours. Distance gust 27, the brothers Henry were able to of second, fifty seconds.” This being recognise the outer satellite with the fine interpreted (or rather, the latter part betelescope of the Paris Observatory; but ing interpreted), means that the outerit was very faint, and could only be seen most, in its circuit around Mars, had when the planet was screened from view. reached its greatest apparent westerly In the mean time, however, two other range at 11 P.M., Washington time, Au. telescopes in America had been used to gust 18, or about 4 A.M., August 19, bring these tiny bodies into view. One Greenwich time (which Astronomers of these was the fine 15-inch Merz re- would call August 18, sixteen hours fractor * of the Harvard Observatory, Greenwich time), and that at this time Cambridge, Mass., celebrated in the his- its seeming distance from the centre of tory of astronomy as that wherewith Sat- Mars was about one twenty-fourth part urn's satellite Hyperion had been de- of the apparent diameter of the moon. tected in 1848. The other was an in- As to the other satellite the news did not strument as large, and doubtless as pow- convey much information. It implied erful, as the Washington telescope itself. that the distance was five-eighths that of It will have been noticed, perhaps, that, the outer moon; but whether that was in speaking of the latter above, we said the greatest distance, or the distance at that it is the finest refractor yet mount- the hour named, there was nothing to ed, not the finest yet made. Messrs. show. As it turned out, there was a Alvan Clark have made a companion in- mistake about this moon, for the greatest strument for the observatory of Mr. range of the moon, east and west of M'Cormick, of Chicago, one of those Mars, amounted only to about threemunificent patrons of science of whom fifths of the distance named. (of late, in particular) America has just In the circular issued by the Secretary reason to be proud. The instrument of the United States Navy (the Hon. R. has not yet left Messrs. Clark's factory, W. Thompson), dated August 21, 1877, and cannot be said to have been yet a copy of which reached the present (properly speaking) mounted. But the writer on September 3, fuller and more Clarks managed to get it turned upon correct details are given, in a form, howMars, and were able to see the Martian ever, which would be quite unsuited to satellites. There is another very fine these pages. We will endeavor to present telescope, by the way, also made by their meaning correctly, but without techMessrs. Clark & Sons, which is now nical expressions. erected at Chicago, where one of the The outer satellite travels at a dismost eminent observers of double stars, tance from Mars's centre, such that, when Mr. S. W. Burnham, has long pursued the planet is at its nearest, the extreme his labors. Its object-glass is 18 inches apparent span of the satellite's path in aperture; and we should have expects would be about one-eleventh part of the ed that, with this aperture and Mr. Burn- moon's apparent diameter. In actual ham's keen vision, the Martian satellites length this range is about 28,600 miles, would have been brought into view. half of which represents the distance We do not hear, however, of their being from the centre of the planet-about seen at Chicago. Perhaps unfavorable 14,300 miles. As Mars has a diameter

of about 4,600 miles, the distance of the * We use the technical term “refractor" as

satellite from his surface is about 12,000 the only convenient way of describing a telescope with an object-glass, as distinguished miles, or, roughly, about one-twentieth from a telescope with a mirror or speculum, of the distance which separates the moon which is called a "reflector."

from the earth. This other moon travNEW SERIES.—Vol. XXVI., No. 6

43

els round Mars in thirty hours fourteen cannot be much more than ten miles, minutes, the possible error in this deter- and may be less. Altogether these obmination at present being about two jects must be regarded as among the minutes. We have seen that it must be most remarkable members of the solar a very small moon. The present writer, system.” in an article in the Spectator which ap- Assigning to this satellite a diameter peared before the circular above men- of ten miles—which we ourselves, for tioned had reached Europe, had indi- the reasons above indicated, consider cated ten miles as the greatest diameter too large—it would appear, at a distance which could possibly be assigned to of 12,000 miles, with a diameter equal to this body. Let us hear what Profes- about the tenth of our moon's, and theresor Newcomb, the eminent mathemati- fore with a disc equal to about a huncian who presides over the astronomical dredth of hers in apparent area. But department of the Washington Observa- being less brightly illuminated it would tory, who has himself seen the satellite, shine with less than the hundredth part has to say on this point. Writing to the of her light. Mars receives from the New York Tribune he remarks that "the sun (and therefore his moons receive) first question which will naturally arise between one-half and one-third as much is, Why have these objects not been seen light as our earth and moon receive, before? The answer is, that Mars is about half when Mars is at his nearest to now nearer to the earth than he has been the sun, and about one-third when he is at any time since 1845, when the great at his farthest from the sun. Thus the telescopes of the present day had hardly light given by the farther of his two begun to be known. In 1862, when moons varies from one two-hundredth to Mars was again pretty near to the earth, one three-hundredth part of our moon's. we may suppose that they were not This part, then, of the Martian moonlooked for with the two or three tele- light is but small in amount, and cerscopes which alone would have shown tainly cannot go far to compensate the them. In 1875 Mars was too far south Martians (as compared with us Terresof the equator to be advantageously ob- trials) for their greater distance fom the served in high northern latitudes. The present opportunity of observing the Of course this moon passes through planet is about the best that could possi- all the phases which we recognise in the bly occur. At the next opposition, in case of our own moon.

It travels very October, 1879, there is hope that the rapidly among the constellations of the satellites may again be observed with the Martian heavens, which are exactly the great telescope at Washington; but Pro- same in all respects as those we see. In fessor Newcomb thinks that during the very little over thirty hours it traverses follo ten years, when, owing to the the entire circuit of the heavens; or over great eccentricity of the orbit of Mars, what would correspond to one of our he will be much farther from the earth zodiacal signs in two and a half hours : at opposition, the satellites may be invis- whereas our own moon takes more than ible with all the telescopes of the world. two and a quarter days traversing one of In the present year it is hardly likely these signs. Its rate of motion may be that they will be visible after October. best inferred, however, from the stateThe satellites may be considered as by ment that, if our moon travelled as fast, far the smallest heavenly bodies yet she would traverse a distance equal to known. It is hardly possible to make her own diameter in a little over two and anything like a numerical estimate of a half minutes, so that her motion among their diameters, because they are seen in the stars would be quite obvious to orthe telescope only as faint points of light. dinary vision. Perhaps the reader may But one might safely agree to ride round be interested to know which constellaone of them in a railway car between tions are traversed by this Martian moon two successive meals, or to walk round in the course of its circuit of the heavens. in easy stages during a very brief va- The zodiac of Mars, or the pathway of cation. In fact, supposing the surface the sun and planets, is nearly the same of the outer one to have'the same reflect- as ours; but her outer moon, instead of ng power as that of Mars, its diameter travelling, as ours does, within the zodi

sun.

star, the

ac, and indeed in a course nearly ap- outer moon shares this motion with the proaching the sun's, ranges far to the stars; but as it is itself travelling all the north and south of the solar pathway in time from west to east among the stars, each circuit. Its path crosses the eclip- going once round in thirty hours fourtic (passing from the southern to the teen minutes, or travelling nearly as fast northern side) at a point between the this way as it is carried the other, it two stars which mark the tips of the appears to move very slowly with referBuil's horns. It runs thence over a ence to the horizon. Suppose it, for inrather barren region rorth of the twin stance, rising in the east in company stars Castor and Pollux, over the Lesser with Fomalhaut. The stellar heavens Lion, through the Hair of Berenice, are carried round, and Fomalhaut passes where it attains its greatest northerly over to the west in twelve hours nineteen distance from the sun's track. Thence minutes. But the moon has in this time it passes onwards across the feet of the moved away eastwards from the star by Herdsman, the body of the Serpent, and nearly two-fifths of a complete circuit, the feet of the Serpent-Holder, crossing or four-fifths of the range from west to the sun's track near the right foot of this east. Instead, therefore, of being on worthy. On its track, now south of the the western horizon with th sun's, it passes over the Bow of the Arch

moon has passed only one-fifth of the er, and thence over his hind feet (the way from the eastern horizon. In angentleman is of the Centaur persuasion), other half-day she has travelled twoover the head of the Crane, and along fifths of the way, and so on. So that, the Southern Fish (not the southernmost roughly, this mcon occupies five halfof the Tied Fishes belonging to the zodi- days, or about sixty hours, in passing. ac, but the single fish into whose mouth from the eastern to the western horizon. the Water-Bearer pours a stream of wa- She is the same length of time below the ter); ranging very closely past the bright horizon. In other words, strange though star Fomalhaut (which it must some- it may seem, this moon, which travels times hide, just as our own moon some- round Mars, or circuits the stellar heavtimes hides the bright Antares and Al. ens, in thirty hours, only completes her debaran). Thence the Martian moon circuit of the Martian skies in about 120 passes athwart the Sea Monster and the hours. She passes through her phases River Eridanus, over the Bull, passing in a little over thirty hours fourteen minvery close indeed to Aldebaran (which it utes; for, supposing her to start from the must sometimes hide from view), to its sun's place on her eastward course, she starting-place between the horns of the gets round again to the place he had Bull. The circuit we have just described occupied among the stars in thirty is very nearly the celestial equator of the hours fourteen minutes, by which time Martian heavens. (The north pole of he has travelled only a very slight the Martians lies near the Tail of the distance eastwards, over which she, Swan, and the bright star Arided of this with her rapid motion, very quickly constellation must be their north polar passes. Thus while she is above the star; the southern pole-star for the Mar- horizon, which she is for about sixty tians is the star Alpha of the Peacock: hours, she passes twice through all her neither this star, nor any part of the phases. Imagine her, for instance, risconstellation, is visible in our northern ing with the sun. With his swifter latitudes.)

diurnal (or apparent) motion westwards One peculiar effect of this outer moon's he leaves her behind, and when he sets. rapid motion among the stars is that it she is, precisely as in the case before moves very slowly in the Martian skies. considered, only a fifth of the way above The whole of the heavenly sphere, as the eastern horizon and already nearly seen from Mars, is of course carried full, being nearly opposite the sun. Very from east to west just as with us, except soon after sunset she is full; and when that, instead of completing a circuit in the sun is about to rise in the east again twenty-four hours, it requires twenty- she is far on the wane, being past her four hours thirty-seven minutes twenty- third quarter, for she is now but twotwo seconds and seven-tenths, that being fifths of the way from the eastern hori. the length of the Martian day. Their zon, where he is. He travels on, her disc

waning more and more, till when he tions, supply one-seventh of the light overtakes her, in the mid-heavens, she is which the full moon gives to us. “new” in the astronomical sense; that But it is by her motions that this moon is, invisible. He passes to the west; is rendered most remarkable among all and when he sets she is near her first the satellites of the solar system. She quarter, being two-fifths of the way from travels round the planet, or, as seen from his place on the western horizon. She the planet, she completes her circuit of waxes till near morning time; but when the stellar heavens, in about 7 hours 3872 the sun rises in the east she is beginning minutes. This is less than a third of to wane, for she is now about a fifth of the time in which Mars turns on his the way from the place opposite to him axis, or in which the stellar heavens are in the west. He travels on, her disc carried round from east to west. So waning more and more, until about the that, as his nearer moon travels more time of sunset, when it is new moon, than three times as fast from west to the sun and moon setting together. east as the heavens are carried from east

But even more singular, though sim- to west, it follows that she has an excess pler, is the behavior of the second moon. of real eastwardly motion equivalent to We know less of the inner than of the more than twice the rate of motion of outer moon, because it is far more diffi- the star-sphere westwards. She moves, cult to see. The brothers Henry, of the then, in appearance, from the western to Paris Observatory, who caught the outer the eastern horizon, and in less than half moon, failed utterly to see the inner one. the time in which the stars or the sun But it is known that its distance from are carried from the eastern to the westthe centre of Mars is about 5,800 miles, ern horizon, thus completing her appaor from the planet's surface about 3,500 rent motion across the skies from west to miles. This moon may have a some- east in about five hours. As she goes what larger diameter than the other, be- through all her phases in about seven cause its proximity to Mars would natu- hours thirty-nine minutes there are not rally make it more difficult to see, and so many changes in her aspect while she might account for astronomers failing to is above the horizon as there are in the perceive a moon which, at the distance case of the outer moon. Her strangest of the outer, must long since have been feature is her rapid motion eastwards, detected. If we allow to it a diameter causing her to pass from the western to of fifteen miles, or about one-18,00oth of the eastern horizon, instead of the usual our moon's, its disc at the same distance way round. Her actual motions among as ours would be only about one-1,1ooth the stars would be very obvious to such of the disc of our moon. But that prox- vision as ours; for she traverses a disimity to Mars which makes this moon so tance equal to our moon's apparent difaint to our eyes must of course make it ameter in forty seconds ! much larger to theirs. It so happens that The moons of Mars have proved as this effect of proximity causes the moon communicative respecting their primary to appear larger to almost one-fourth the as our own moon has shown herself redegree in which her real surface (or disc specting our earth. As Newcomb well seen at equal distance) is less than that remarks, Leverrier's determination of the of our moon, on the assumption we have mass of Mars (at about one-118th part made. Thus she has a disc, always on of our earth's mass) was the product of this assumption be it remembered, equal a century of observations and several to about a quarter of our moon's; and years of laborious calculation by a corps being illuminated by the sun, like the of computers; whereas from the measother moon, with a light varying from ures of the satellite on four nights only, one-half to one-third that which he pours ten minutes' computation gave a value on the earth, it follows that the light of the planet's mass in striking agreeshe reflects to Martians, or would re- ment with Leverrier's—viz., one-113th flect to them if there were any such of the earth's mass. Moreover, this valheings, varies from one-eighth to one- ue, though obtained in so short a time, twelfth of that which we receive from is more trustworthy than Leverrier's. It the full moon. The two moons together amounts to a reduction of the planet's do not, under the most favorable condi- mass by one-2ooth part of the earth's, or by a trifle of about thirty millions of mil- heavenly bodies." The other is from lions of millions of tons.

Voltaire's Micromégas, Histoire PhilosoWe may add, in conclusion, two curi- phique. The Sirian giant, with a Saturous anticipations of the late discovery. nian friend, visited the neighborhood of One is well known-Swift's account (pro- Mars : "Ils côtoyèrent la planète (de bably corrected in this place by Arbuth- Mars, qui, comme on sait, est cinq fois not, for Swift was no arithmetician) of plus petite que notre petit globe; ils the discoveries made by the Laputan as- virent deux lunes qui servent à cette tronomers. “They have likewise dis- planète, et qui ont échappé aux regards covered two lesser stars,” he says, or de nos astronomes. Je sais bien que le satellites, which revolve about Mars, père Castel écrira, et même assez plaiswhereof the innermost is distant from amment, contre l'existence de ces deux the centre of the primary planet exactly lunes; mais je m'en rapporte à ceux qui three of his diameters and the outermost raisonnent par analogie. Ces bons phifive; the former revolves in the space of losophes là savent combien il serait diffiten hours and the latter in 21/2, so that cile que Mars, qui est si loin du soleil, se the squares of their periodical times are passât à moins de deux lunes.” Beyond very nearly in the same proportion with all doubt both these pleasantries had the cubes of their distance from the cen- their origin in the idea thrown out by tre of Mars, which evidently shows them Kepler in 1610, when Galileo announced to be governed by the same law of to him the discovery of the four moons gravitation that influences the other of Jupiter. *-Cornhill Magazine.

THE KHEDIVE'S EGYPT, AND THE ROUTE TO INDIA. The Khedive's Egypt; or, The Old House relations with the principal public men. of Bondage under New Masters. By Edwin of Egypt; and it will appear, from a de Leon, ex-Agent and Consul-General in Egypt. New York : Harper & Bros.

perusal of the interesting pages now un

der remark, that although Mr. De Leon The Khedive's Egypt has this point feels natural partiality for a ruler from of resemblance to the Egypt of the Pha- whom during a long acquaintance he has raohs—that the people of the soil are received many marks of kindness and ground down and oppressed by cruel consideration, he does not on that actaskmasters now, as they were in and be- count extenuate his faults, while giving fore the days of Moses.

him full credit for his good qualities. What the Pyramids were to the poor Egyptian of the time of Cheops-what eight years of age, under the middle height,

“Ismail Khedive is a man of about fortythe treasure-cities Ramses and Pithom but heavily and squarely built, with broad were to the Israelites-the Suez Canal shoulders, which, during the last year, seem and the other public works undertaken to have become bowed down by the heavy during his reign have been to the poor has so manfully struggled. His face is round,

burdens imposed upon him, under which he Egyptians of the Khedive Ismail who covered by a dark brown beard, closely cliphave been sacrificed by thousands on ped, and short moustache of the same color, the altar of progress” erected by their shading a firm but sensual mouth. His comruler.

plexion is dark; his features regular, heavy Mr. De Leon in respect to Egypt, the which he keeps habitually half closed, in.

rather than mobile in expression. His eyes, character of its ruler, and the condition of its people, speaks with an authority derived from an intimate personal ac

* Since the above was written Mr. Wentquaintance of many years' duration with nounced that the outer satellite has been seen

worth Erck, of Sherrington, Bray, has anthe country. American Consul-General three times with his seven-inch Alvan Clark at Cairo during the Crimean war, he re- telescope. In one of these observations a signed that post to throw in his fortunes small star was certainly seen; the others seem with his native South at the commence

to have been real observations of the satellite.

Either Newcomb must have underestimated. ment of the great American struggle. the satellite's brightness, or else its surface is . But he has ever since kept up intimate of such a nature that it varies in lustre.

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