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An old nurse was sitting by the fire sewing. The two elder children were asleep; but the youngest, an audacious young sinner of three, had refused to do anything of the kind until the cat came to bed with him. The nursery cat being at that time out a-walking on the leads, the nursemaid had been despatched to borrow one from the kitchen. At this state of affairs Mary entered. The nurse rose and curtsied, and the rebel clambered on her knee, and took her into his confidence. He told her that that day, while walking in the square, he had seen a chimney-sweep; that he had called to Gus and Flora to come and look; that Gus had been in time and seen him go round the corner, but that Flora had come too late, and cried, and so Gus had lent her his hoop and she had left off, &c. &c. After a time he requested to be allowed to say his prayers to her; to which the nurse objected, on the theological ground that he had said them twice already that evening, which was once more

than was usually allowed. Soon after this the little head lay heavy on Mary's arm, and the little hand loosed its hold on hers, and the child was asleep.

She left the nursery with a thankful heart; but, nevertheless, she cried herself to sleep. "I wonder, shall I like Lady Hainault; Charles used to. But she is very proud, I believe. I cannot remember much of her. - How those carriages growl and roll, almost like the sea, and dear old Ravenshoe." Then, after a time, she slept.

There was a light in her eyes, not of dawn, which woke her. A tall, handsome woman, in silk and jewels, who came and knelt beside her and kissed her, said that, now her old home was broken up, she must make one there, and be a sister to her, and many other kind words of the same sort. It was Lady Hainault (the long Burton girl, as Madam Adelaide called her) come home from her last party; and in such kind keeping I think we may leave little Mary for the present.

To be continued.

THE LAW OF BODE; OR, GAPS IN THE SOLAR SYSTEM FILLED UP.

A SKETCH FROM RECENT ASTRONOMICAL HISTORY.

BY PROFESSOR KELLAND.

LET us go back in fancy to the time when the clang of the church-bells and the shouts of the populace announced the coming in of a new year, and that year the first of our present century. It is, indeed, a time of great excitement. With the old century have gone down to the grave half the governments of Europe; and men are straining their eyes on the dawn of the new year to pierce through the dark curtain into something brighter and better beyond. The revolutionary torrent has swept away the old landmarks of civilization, monarchical and moral. The accustomed greeting, "A happy new year!" comes now with fearful significancy-for who can say what shall follow ?

From the feverish excitement of the ts it is refreshing to enter the

solitary chamber of the astronomer. In the observatory of Palermo, all unconscious of the bustle without, we find the astronomer Piazzi. He, too, is watching for the new year. But not idly watching! He is casting a nativity. His eye is steadily fixed on some unknown object in the heavens; and a flush comes over his cheek as he dreams-hopes, perhaps, - that he shall enter on it as a fair possession, that his name shall live in it for ever. His hope is realised. The object on which he is intent is a new planet-the planet Ceres-seen now for the first time, the star of the new century, the harbinger of union and completion. Happy horoscope !

We must be more particular in describing this event. Let me begin by remarking that the human mind is more adapted for seeking, than for selecting objects of search-more a workman than a projector. And so it has happened that many fields of knowledge have lain fallow for years, simply because the popular voice had proclaimed the soil exhausted. A little more than a century ago, a distinguished natural philosopher pronounced the mechanical sciences complete. Every corner of his limited field had been explored; and he never dreamt that there were fertile districts beyond, and still beyond, which the next generation should enter on with as much facility as the generation past had entered on their allotted work-field. Happily there have been permitted a few phantoms of the imagination, which, dancing like ignes fatui before the eyes of searchers after truth, have led them through the mazes of certain branches of science. Still, as they advanced, the object of their search ever eluded their grasp, and they have at length rested from their labours, not like the worthies who followed dainty Ariel,

"i' the filthy mantled pool up to the chins," but in some green meadow, better than the goal they sought. Of this kind of phantoms are the Philosopher's Stone, which helped chemistry into life; the Quadrature of the Circle, which kept geometry in motion; and the law known as "Bode's law," to which astronomy is largely indebted. To this law I am about to direct your attention. Milton, speaking of the mystical dance of the planets, said that

"In their motions, harmony divine

So smooths her charming tones, that God's

own ear

Listens delighted -."

He spake but as others thought. He gave poetic utterance to the prevalent idea of the mutual dependence of the planetary motions. That some harmonious relation should exist amongst the distances of the planets from the sun, must have occurred to the minds of astronomers as soon as these distances came to be tolerably well ascertained. But, try as they might to discover the relation, little harmony resulted from

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their trials. Even that strange and wonderful dreamer, Kepler, "the legislator of the heavens," with his piles of pyramids and circles, could evolve no law, save on one condition-that planet should exist between Mars and Jupiter. Others tried their hands in other ways; but there always came out the same condition-a missing planet to be restored. The simplest law, and that which obtained the firmest hold of the German mind, is that known as the law of Bode, enunciated about a century ago. It is not necessary to express the law fully; it will suffice to say that it requires that the distances between two consecutive planets (Mercury excepted) should go on doubling as you recede from the sun. Thus the distance of Mars from the Earth is double the distance of the Earth from Venus. The law, be it observed, had nothing whatever to rest on. It was the merest figment. But, like an uneasy dream, it haunted the minds of astronomers; and when, in 1781, Uranus appeared in the distant regions of space, fulfilling that law, (Uranus is, indeed, almost accurately, twice as far from Saturn as Saturn is from Jupiter), it was hopeless to expect men to shake off the impression of its truth. Accordingly we find Baron Zach, in the Berlin Almanack for 1789, gravely setting down the elements of the planet between Mars and Jupiter which the law required, as if such a planet really existed, and had been observed. He asserted that its distance from the sun is 268 millions of miles, and its periodic time 4 years. The law of Bode was indeed but a dream; yet, like the vision of Daniel, it changed the countenance of the dreamers. Accordingly, in 1800, a conference was held in Lilienthal, in which it was resolved by the astronomers present to form themselves into an association to search for the supposed planet. Letters were posted to the different observers throughout Europe, inviting their co-operation. A letter was actually on its way to Piazzi, the astronomer at Palermo; but, before he had received it, or had become acquainted with the proceedings of the association, the planet had been found by him, on the 1st of January, 1801, the first day of the present century. The event seems to mark the century as one in which the old paths would be retrodden, and be found to abound in riches unseen to the ages which had passed over them.

But how about the dream? Strange to say, unlike the vision of the morning and the evening rehearsed in Babylon which was true, but none understood itthis vision yielded realities through the interpretation of a figment of the imagination. The distance of Ceres from Jupiter was to a nicety double its distance from Mars; and the periodic time round the sun, which Baron Zach had predicted to be 42 years, turned out to be actually upwards of 41. But the planet was very small; so small and so ill-shaped as hardly to deserve the name of a planet. It seemed like a huge fragment of rock, struck off from some larger globe. This fact induced Olbers to conjecture that it was only the portion of a planet which had burst from some internal explosion. He expected that, if search were made, other similar fragments would be picked up; and he had himself the good fortune to discover one on the 28th of March, 1802, and a third on the 29th of March, 1807. Meantime a fourth had been discovered by Harding. occurs one of those remarkable blanks which present themselves in the annals of every branch of scientific discovery. The wise and gracious Disposer of Events seems to mete out to each generation its proper limit of success, that future ages may have a store reserved for the exercise of their faculties. The history of the steam-engine, the history of optics, equally with that of astronomy, exhibit stations of unaccountable arrestment. A restraining hand seems to hide, with the thinnest veil, bright objects from the eyes of searchers. Not a single addition was made to the catalogue of these little planets-asteroids, as they are called from March, 1807, to December, 1845384 years. It was not because they were not sought for that they were not

And

now

found. On the contrary, the look-out had been most careful. Olbers states, that from 1801 to 1816 he had examined the part of the heavens where the other asteroids had been discovered, with such strict scrutiny and unfailing regularity, that he was quite certain no new planets had passed. On the 6th December, 1845, Professor Hencke had the good fortune to find a fifth asteroid, naming it Astræa; and now, in 1861, seventeen years later, the number has been increased by sixty-two more. No less than eight were discovered in one year, 1857, and we may reasonably expect four or five annually. We owe this abundant crop of planets to the excellence of the German star-maps, and to the new mode of observation, which consists in constantly comparing a district of the heavens with its map. The difficulty is now no longer to find planets, but to find names for them. The English discoverer, Hind, names one of his Victoria, and the French discoverer, Goldschmidt, names one of his Eugenia. The Pantheon is exhausted -very nearly at least, only a muse or two being left; and Urania is weeping because men will persist in desecrating the skies by raising mortals to them.

There is little to add about the asteroids, and that little of no great importance. The interest which attaches to their discovery is all expressed when we say that they were wanted and looked for. I will pass on then to another case of anticipation of a still higher class.

I have spoken of the empirical law of Bode as a dream; but it was not the only dream which haunted the waking hours of the German mind during the latter half of the last century. There was another dream equally unsubstantial, and almost equally fruitful. Kant, the great metaphysician, had confidently asserted that there would be found at least one planet beyond Saturn; and his reason was this-that, as nature does not operate abruptly, she must have filled up the interval between the planets and the comets with some intermediate bodies. The reason may be good or bad; it is certain that men were on the look-out. Twenty years after the prediction is uttered, Uranus enters on the stage, filling up some portion of the gap. The German metaphysician is right: the planet has appeared in obedience to the prediction. But it has done more. It has appeared at a distance from Saturn only a little more than double the distance of the latter from Jupiter-just what the law of Bode required. The German dreamer is right, too.

Twenty years, save one, pass away, concluding the century, and Ceres appears, as we have explained, filling up the gap between Mars and Jupiter. Here are two facts-enough, in good sooth, says the German mind. On these I can build a theory that shall span the heavens. The law of nature is a law of continuity, argues Kant. The law of planetary distance is a law of duplication, argues Bode. Facts have borne out both arguments. Accordingly, when Ceres ushered in the present century, she was received throughout Germany as a long-expected stranger, and in many quarters as the harbinger of another and another planet. We have seen how Dr. Olbers took up the matter, and with what triumphant success. But astronomers did not limit themselves to the space between Mars and Jupiter. They saw in the dim distance a chain of bodies stretching away from Uranus to the dogstar. They even went further. They gave to the remote imaginary planet next in succession in the vast abyss "a local habitation and a name." In Jacobi's pocket-book for 1802 we read thus-" Ophion, the next planet beyond "Uranus, is 780 millions of (German) "miles distant from the sun, and has an " orbit of 250 years. It is not yet dis"covered."

Twice twenty years pass on. The heavens have been swept in every likely direction, but without result. Expectation has long since gone to rest. But now there begins to be experienced a tremor on the outskirts of our system, an unsteadiness in the march of the remotest planet, which seems to indicate the existence of a body beyond his orbit, dogging his path and disturbing the

serenity of his movements. Some astronomers thought the law of gravitation at fault, but the wisest men reverted to the now almost forgotten notion of an outer planet. Amongst these was the illustrious Bessel. Speculations like the following began to find favour. Mädler, in 1841, writes-"Had we possessed "very exact Saturnian observations [prior "to 1781], extended over a long series "of years, it might have been possible "to have discovered Uranus theoretically " by analytical combinations before Her"schel found it (by telescopic observa"tion);" and he adds, applying this conclusion to Uranus, "We approach a "planet acting upon and disturbing it;

yes, we may express the hope that "analysis will, some time or other, "solemnize this, her highest triumph"making discoveries with her mind's

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eye in regions where our actual sight "has failed to penetrate."

This is the language of a visionarya dreamer; but a dreamer of a very different cast from those we have already been speaking of. The dreams of the astronomer of Dorpat, and such as he, were like those of that strange deaf dreamer Kitto, who, when in the lowest depths of poverty, and the most pitiable state of helplessness, saw himself in a dream risen in station, and surrounded by books and manuscripts all his own; while into those ears where earthly sounds could find no access an angel whispered words which, like the touch of Ithuriel's spear, caused the vision to start up into a reality. These were, in truth, no dreams. Sparks from the anvil of time's workshop fell hot and hissing on the souls of astronomers. A student, young and unknown, sits in his lonely rooms in St. John's College, Cambridge. It is vacation-time, but vacation-time finds him hard at work. And, as he works, a spark reaches his soul, and kindles within him the desire to be, like Columbus, the discoverer of a world. The drift thrown upon Uranus from the dark ocean tells him that there is life beyond; and he longs to set out on a voyage of discovery. But his longings cannot yet be satisfied; so he writes in his journal of the 3d of July, 1841-"Formed a "design of investigating, as soon as pos"sible after taking my degree, the irre"gularities in the motion of Uranus, in "order to find whether they may be "attributed to the action of an undis"covered planet beyond it, and, if pos"sible, to determine the elements of its "orbit, which would probably lead to " its discovery." Good resolutions often come to nought; but this was more than a good resolution-it was a great resolution. And great resolutions are the forerunners of great deeds. They belong to great minds. The servants of Naaman knew their master when they said, "If the prophet had bid thee do some great thing, wouldest thou not have done it?" And so this young man acts upon his great resolve, and consecrates some of the best years of his life the years which others in his circumstances would have devoted to the acquisition of a little of this world's good-to a patient search after the disturbing agent which is at work on the remotest planet of our system. And the work is done. The planet is found. But here again occurs one of those remarkable conjunctions with which the history of science abounds. Whilst Mr. Adams is quietly pursuing his calculations at Cambridge, another man is occupied with a similar work in Paris. And the results are almost coincident. Adams had caught the planet-it was in his net; but, from the want of an accurate star-map, there required some little time for its identification. The process was going on surely and steadily; but it was incomplete, when Leverrier stepped in and bore off the prize. Of course you will conclude that astronomers so distinguished as Adams and Leverrier gave no heed to an empirical law like that of Bode, which had not even the semblance of a basis to stand on. You are wrong. Both astronomers tacked that law to their preliminary hypotheses. They used it just as a statesman would use rumours of a French invasion. They don't believe a word of it, but there can be no harm in employing it in the construction of a nation of sharpshooters!

As an episode to this curious history, it remains to be added that M. Leverrier, having succeeded so wonderfully in detecting a planet situated beyond the outer borders of the known system, naturally set to work to try his hand on the space lying between Mercury and the sun. The result was that, on the 2d of January, 1860, he announced that the irregularities traceable in the motion of Mercury would be made to disappear if a planet of the size of Mercury, and situated at half his distance from the sun-or, better still, if a group of planets like those which we have spoken of, lying between Mars and Jupiter-should be found. But in the dazzling proximity of the sun it was no easy matter to look for such bodies. They might exist, and their places might be pretty well determined, as was the place of Neptune; but what eagle-eye should pierce through the rays of the sun? Whilst men were debating this question a rumour arose that the thing had already been done. A medical practitioner residing in the provinces of France had been addicted to astronomy from his infancy, and for twenty years had been ruminating on the law of Bode; and, being led, by studying that law, to believe the possibility of the existence of a planet between Mercury and the sun, he had argued that, if there is such a planet, he must often cross the sun's disk. Accordingly, whenever his professional duties allowed him leisure during the day, he set himself on the watch. On the 26th of March, 1859, he observed the passage of the body he had been looking for. This circumstance is made known to Leverrier soon after the publication of the memoir referred to. He hastens down to the country, and marches up to the doctor's residence. The worthy man, whose name is Lescarbault, submits to the astronomer's crossexamination. He demands the record of the observations, and it is found covered with grease and laudanum, performing the part of marker in the Connaissance des Temps. He asks for the rough drafts of the calculations which have led M. Lescarbault to the conclusion that the planet's distance is half

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