munificent gifts of Rudolph. He selected the | logue, as originally published in the Progymnas afterwards increased, by Kepler, from the original observations to 1005; and it is to be kept in mind, that all the observations were made with extrameridional instruments, and reduced by the laborious method of distances. This monument of Tycho's industry was republished last year, (1843,) along with some other ancient catalogues; under the care and at the expense of a private gentleman, to whose unostentatious liberality various sciences, but especially astronomy, have been under important obligations." castle of Benach, but after a few months trans- mata, contained 777 stars; but the number was ferred his family and instruments to a house which had been purchased for him in Prague. But his career was now drawing to a close. He removed to Prague in February, 1601. On the 13th of October, in the same year, while supping at the table of a nobleman, where they drank freely, he experienced some feelings of discomfort, but, from motives of courtesy, he remained at table, and on his return home was seized with a retention of urine, in consequence of which he expired, after ten days of extreme suffering. He died in the 55th year of his age; his last words, repeated frequently during his delirium, being Ne frustra videar vixisse. Such is a brief outline of the life of this remarkable man. To appreciate the services which he rendered to astronomy, it is necessary to consider the state of the science at the time he commenced his labors. The question between the rival theories of Ptolemy and Copernicus was then undecided; and as both hypotheses sufficed for the explanation of the observed phenomena, and afforded nearly equal facilities for calculation, no further advance could be made without more numerous and accurate observations. This was precisely what Tycho undertook to supply. Born in a favorable position, possessing independent resources, and liberally aided by the king of Denmark, he erected an observatory of more than regal magnificence; constructed or procured instruments superior in magnitude and accuracy to any that had been previously seen; engaged the services of able and zealous assistants, and devoted himself to assiduous observation during a long series of years. The result was the accumulation of a large mass of very accurate observations, which, falling into the hands of Kepler, led to the discovery of the true nature of the planetary orbits, and a complete revolution in astronomy. Although Tycho's principal merit is that of a diligent and accurate observer, various results which he deduced from his observations were important improvements in theory. He was the first who pointed out the diminution of the obliquity of the ecliptic. He detected several inequalities in the moon's motions, and determined their law. He proved from the parallax of comets that these bodies are situated far beyond the orbit of the moon, and consequently that the heavens are not, as was then supposed, solid transparent spheres. He formed the first table of refractions; imperfect, no doubt, as it extended only to 45° in altitude;but before the discovery of the telescope, the effect of refraction beyond that altitude was insensible. He introduced into practical Astronomy various improvements on the methods of observing; and he set the example of carefully verifying his instruments, and ascertaining the amount of instrumental errors. But the most valuable result of his labors is his catalogue of fixed stars. The cata The claim of Tycho to be regarded as a martyr of science rests solely on the circumstances, whatever they were, that led to the withdrawal of his pensions, and his exile from Denmark. Among the losses he sustained on this occasion, the one which he must have most deeply regretted was his observatory, which had been erected at so great an expense, and of which his biographers have given such glowing descriptions--descriptions which, were it not for the minuteness of their details, and the confirmation they receive from the plans and drawings given by Tycho himself, we might almost suppose to have belonged to a romance. The following extract will show Tycho's notions of the accommodation required for an astronomer. After describing the ceremony of laying the foundation, which was done in presence of the king, and at which "copious libations of a variety of wines were offered for the success of the undertaking," Sir David Brewster thus pro ceeds : "The observatory was surrounded by a rampart, each face of which was three hundred feet long. About the middle of each face the rampart became a semicircle, the inner diameter of which was ninety feet. The height of the rampart was twenty-two feet, and its thickness at the base twenty. Its four angles corresponded exactly with the four cardinal points, and at the north and south angles were erected turrets, of which one was a printing-house, and the other the residence of the servants. Gates were erected at the east and west angles, and above them were apartments for the reception of strangers. Within the rampart was a shrubbery with about three hundred varieties of trees; and at the centre of each semicircular part of the rampart was a bower or summer-house. This shrubbery surrounded the flower garden, which was terminated within by a circular wall about forty-five feet high, which enclosed a more elevated area, in the centre of which stood the principal building of the observatory, and from which four paths led to the above-mentioned angles, with as many doors for entering the garden. "The principal building was about sixty feet square. The doors were placed on the east and west sides; and to the north and south fronts were attached two round towers, whose inner diameter "The Catalogues of Ptolemy, Ulugh Beigh, Tycho Brahé, Hevelius, deduced from the best authorities; with various Notes and Corrections, and a Preface to each Catalogue." By Francis Baily, Esq. Forming vol, xiii. of the Memoirs of the Royal Astronomical Society. was about thirty-two feet, and which formed the observatories, which had windows in their roof that could be opened towards any part of the heavens. The accommodations for the family were numerous and splendid. Under the observatory, in the south tower, was the museum and library and below this, again, was the laboratory, in a subterraneous crypt, containing sixteen furnaces of various kinds. Beneath this was a well forty feet deep, from which water was distributed by syphons to every part of the building. Danish court. Many of the nobles envied the munificent establishment he had received from Frederick, and the liberal pension which he drew from the treasury. But among his most active enemies were some physicians, who envied his reputation as a successful and a gratuitous practitioner of the healing art. Numbers of invalids flocked to Huen; and diseases, which resisted all other methods of cure, are said to have yielded to the panaceal prescription of the astrologer. Under the influence of such motives, these individuals succeeded in exciting against Tycho the hostility of the court. They drew the public attention to the exhausted state of the treasury. They maintained that he had possessed too long the estate in Norway, which might be given to men who labored more usefully for the commonwealth; and they accused him of allowing the chapel at Rothschild to fall into decay."-(p. 168.) "As the two towers could not accommodate the instruments which Tycho required for his observations, he found it necessary to erect, on the hill about sixty paces to the south of Uraniburg, a subterranean observatory, in which he might place his larger instruments, which required to be firmly fixed, and to be protected from the wind and weather. This observatory, which he called Stiernberg, [Stiernburg,] or the mountain of the stars, consisted of several crypts, separated by solid The story about the jealousy of the physicians walls, and to these there was a subterranean pas-is given by Gassendi in rather stronger terms; but sage from the laboratory in Uraniburg. The it would seem to rest on no better foundation than various buildings which Tycho erected were in the following verses, in an elegy composed by a regular style of architecture, and were highly Tycho on the occasion of his departure. After ornamented, not only with external decorations, but with the statues and pictures of the most disalluding to his medical practice, he adds— tinguished astronomers, from Hipparchus and Ptolemy down to Copernicus, and with inscriptions and poems in honor of astronomers."-(pp. 148–151. Not the least remarkable circumstance connected with this magnificent structure, was its speedy demolition, without apparent cause or object. Even when Gassendi wrote, the edifice, with all its towers and ramparts, had entirely disappeared jam seges est ubi Troja fuit—and when Picard was sent to Huen, by the Academy of Sciences of Paris, in 1671 for the purpose of determining the exact position of the spot where the instruments had stood, he found only some remains of foundations; the whole structure, he remarks, having been demolished soon after Tycho's departure, and the materials partly used in the construction of a farm-house. What renders its demolition more unaccountable, is the circumstance, that in the time of Tycho the island contained only one village, with about forty inhabitants. It could scarcely be necessary to pull down a castle to obtain building materials for the houses required for such a population. The causes of Tycho's rupture with the Danish court have been left by preceding biographers without satisfactory explanation; and Sir David Brewster has not thrown any new light on the subject. Tycho himself does not name his persecutors; but, in his elegies and private letters, hints at vague charges of ingratitude and oppression; declares he will tell all at the proper time and in the proper place; and piously suggests that his persecution was ordained by Providence, for the purpose of more widely diffusing a knowledge of astronomy. The reasons set forth in the following paragraph, afford no satisfactory explanation of the mystery : "For several years the studies of Tycho had been treated with an unwilling toleration by the « Nec tamen hinc lucrum sectabar, ut undique moris; * He appoint ed a committee of two persons, one of whom was Thomas Feuchius, to report to the government on the nature and utility of the studies of Tycho. These two individuals were entirely ignorant of astronomy and the use of instruments; and even if they had not, they would have been equally subservient to the views of the minister. They reported that the studies of Tycho were of no value, and that they were not only useless, but noxious. Armed with this report, Walchendorp prohibited Tycho, in the king's name, from continuing his chemical experiments."-(p. 171.) Passing over the assumed subserviency of Feuchius and his coadjutor, we may remark, that astronomers have no great reason to find fault with the sentence consequent on their report; nor is it probable that chemistry lost much by the prohibition of Tycho's experiments. The charges against Walchendorp of possessing real endowments, the idol devours would seem to require some further support, in order to entitle them to be received as matter of authentic history. the meats which are offered to him, without analyzing the motives and expectations under which he is fed. Even when the idolator and his god are not placed in this transverse relation, the love of power or of notoriety is sufficient to induce good men to lend a too willing ear to vulgar testimony in favor of themselves; and in our own times, it is not common to repudiate the unmerited cheers of a popular assembly, or to offer a contra diction to fictitious tales which record our talents or our courage, our charity or our piety.”—(p. 191.) Beyond the credit due to Tycho as a practical astronomer, his character presents few points for admiration, and is even stained with the grossest weaknesses and defects. He was a believer in astrology, and a confirmed alchemist;-the discoverer of a new elixir, or universal remedy, "which went by his name, and was sold in every apothecary's shop as a specific against the diseases which were then ravaging Germany." Astrolo- We proceed now to a character of a very differger, alchemist, and quack, he also aspired to be ent class;-one of those rare men, says Laplace, regarded as a conjurer. "He had various auto-whom nature bestows from time to time on the mata, with which he delighted to astonish the sciences, in order to develope the great theories peasants; and by means of invisible bells, which prepared by the labors of many ages. Kepler was communicated with every part of his establishment, born at Wiel, in the duchy of Wirtemberg, on the and which rung with the gentlest touch, he had 21st of December, 1571, and was consequently great pleasure in bringing any of his pupils sud-twenty-four years younger than Tycho, and seven denly before strangers, muttering at a particular years younger than Galileo. His father and motime the words, "Come hither, Peter," as if he ther are represented as having both been of noble had commanded their presence by some super- extraction, but reduced to indigence by their imnatural agency.'-(p. 196.) The following ex-providence or bad conduct. The nobility of his tract shows that the study of astronomy had not descent, however, afforded him no immunity from elevated his mind above the most abject supersti- the usual inconveniences of poverty; his father, tions:who had been a petty officer in the Duke of Wir "If, on leaving home, he met with an old wo-temberg's service, became ultimately the keeper man, or a hare, he returned immediately to his of a tavern at Elmendingen; and he himself, at house. But the most extraordinary of all his pe- the age of twelve years, was employed in menial culiarities remains to be noticed:-When he lived offices in this establishment. In his youth he was at Uraniburg, he maintained an idiot of the name of a feeble and delicate constitution, and subject to of Lep, who lay at his feet whenever he sat down to dinner, and whom he fed with his own hand. periodical attacks of severe illness. At the age of Persuaded that his mind, when moved, was capa- fifteen he was admitted into the school of the monble of foretelling future events, Tycho carefully astery of Maulbronn, whence, in due time, he proremarked everything he said. Lest it should be ceeded to the university of Tubingen. Here he supposed this was done to no purpose, Longomon-had Michael Mostlin for his preceptor in mathetanus relates that when any person in the island matics-an astronomer of no mean repute, and to was sick, Lep never, when interrogated, failed to whom the credit is due of being one of the first predict whether the patient would live or die."(p. 197.) who publicly taught the system of Copernicus. and, on taking his degree of master, in 1591, he Under this tuition Kepler made rapid advances; held the second place at the annual examination. Our author, in an eloquent paragraph, which we regret our limits will not permit us to transfer wholly to our pages, has, with a view to extenuate some of these defects of Tycho's character, discussed the question how far a belief in Alchemy, and the practice of its arts, have a foundation in the weakness of human nature; and to what extent they are compatible with piety and elevated moral feeling. We can only make room for the following passage :— In the biographies of great inventors we expect. manifestations of the ruling passion in early youth, to find, almost as matter of course, not only some but indulgence in the favorite pursuits at a more advanced period, in spite of every obstacle and discouragement. Thus Tycho was sent to Leipsic to study law, but passed his nights in measuring the distance of the stars. Galileo was placed at Pisa to study medicine, but gave his whole mind to mechanics. Kepler, however, cannot be cited as an example in illustration of the rule, for he took to astronomy as a matter of duty. On the recommendation of Mastlin, he was appointed, in 1594, to the professorship of astronomy at Gratz -an office for which he had, at that time, no particular qualification; and he himself states, that "The history of learning furnishes us with many examples of that species of delusion in which a great mind submits itself to vulgar adulation, and renounces unwillingly, if it renounces at all, the unenviable reputation of supernatural agency. In cases where self-interest and ambition are the basis of this peculiarity of temperament, and in an age when the conjurer and the alchemist were the companions and even the idols of princes, it is easy to trace the steps by which a gifted sage retains his ascendency among the ignorant. The heca. he had no predilection for the science, but having tomb, which is sacrificed to the magician, he re- been educated at the public expense, he felt himceives as an oblation to his science; and conscious self constrained to accept the first appointment that was offered him. His attention being thus | forgotten. "No adverse circumstances were cadirected to astronomy, he embarked in the study pable of extinguishing his scientific ardor, and, with the eagerness for which he was remarkable whenever he directed his vigorous mind to the inthrough life, devoting the whole energies of his vestigation of phenomena, he never failed to obtain mind to discover the causes of the number, the interesting and original results." At this period, size, and the nature of the planetary orbits. The he occupied himself with researches on the subject fruits of this application appeared in 1596, in his of refraction. His "Supplement to Vitellio" was "Prodromus of Cosmographical Dissertations ;"- published in 1604;-a work which contained the a work of which the object appears to have been best account of astronomical optics then extant, to prove, that the Creator of the universe had ob- and in which the offices performed by the different served the relations among the five regular solids, parts of the eye, in the act of vision, were first disin determining the order, number, and proportions tinctly explained. In 1611, he published another of the planetary orbits. Wild and extravagant as work on the same subject, his "Dioptrics," which were the theories propounded in this remarkable vol- contains the first theoretical explanation which was ume, the boldness and originality of genius, as well given of the construction of the telescope. But as powers of application which it manifested, called the most important result of his labors at this peforth the approbation of Galileo and Tycho, and riod of his life, and indeed by far the most valuastamped the author as one of the first astronomers ble of all his productions, was his "Commentaries of the age. Kepler's position at Gratz was by no on the Motions of Mars," which appeared in 1609. means an agreeable one. The feuds between the In this remarkable work he has recorded the variCatholics and Protestants, which then agitated the ous steps by which he was led to two of his greatcity, were a source of continual annoyance to him; est discoveries; namely, that the orbit of Mars is his income was insufficient for his support; he had an ellipse having the sun in one of its foci; and married, and his wife's dowry having turned out that the time of describing any arc is proportioned less than he had been led to expect, he was in- to the area included between the curve and two volved in disputes with her relations. In 1600 he straight lines drawn from the sun to the extremivisited Tycho at Prague, for the purpose of ob- ties of the arc. These important laws, together taining from that astronomer more accurate data with the correct views on gravity disclosed in this for the determination of the eccentricities of the work, entitle its author to be regarded as the preplanets; and an arrangement was proposed where- cursor of Newton and Laplace, and the founder of by he should become one of Tycho's assistants. celestial mechanics. Before this plan could be carried into effect, Kepler, in consequence of fresh troubles at Gratz, was induced to resign his appointment at that place; and being thus left without the means of subsistence, he applied for the professorship of medicine at Tubingen. From this purpose, which would probably have given an entirely different direction to his studies, he was dissuaded by Tycho; who "When Kepler presented to Rudolph the volinvited him to Prague, presented him to the empe- ume which contained these fine discoveries, he reror, and procured for him the title and emoluments minded him jocularly of his requiring the sinews of imperial mathematician, on the condition that he of war to make similar attacks upon the other planets. The emperor, however, had more formishould assist in reducing the observations. Lon-dable enemies than Jupiter and Saturn, and from gomontanus was at that time Tycho's first assist- the treasury, which war had exhausted, he found ant, and it was agreed that they should undertake it difficult to supply the wants of science. While the computation, from Tycho's observations, of an Kepler was thus involved in the miseries of poventirely new set of astronomical tables; to be erty, misfortunes of every kind filled up the cup called, in honor of the emperor, the "Rudolphine victim of low spirits, was seized, towards the end of his adversity. His wife, who had long been the Tables." The proposal was encouraged by the of 1610, with fever, epilepsy, and phrenitis, and emperor, who pledged himself to defray the ex-before she had completely recovered, all his three penses of the publication; but the death of Tycho, in 1601, and the return of Longomontanus to Copenhagen, put an end to the scheme for the pres ent. Upon the death of Tycho, Kepler succeeded him as first mathematician to the emperor, and came into possession of his invaluable collection of observations. To this office a handsome salary was attached; but the imperial treasury being drained by expensive wars, Kepler experienced great difficulties in providing a subsistence for his family. But his astronomical pursuits were not As an account of this volume, and of Kepler's principal astronomical discoveries, has been given in a former number of this Journal, we shall not dwell on them here, but proceed to give a few more incidents of his personal history. The melancholy posture of his private affairs about this time, is thus described by Sir David Brewster : children were simultaneously attacked with the small pox. His favorite son fell a victim to the tially occupied by the troops of Leopold. The malady, and, at the same time, Prague was parpart of the city where Kepler resided was harassed by the Bohemian levies, and, to crown the list of evils, the Austrian troops introduced the plague into the city."-(p. 228.) In consequence of his pecuniary embarrassments. Kepler made an attempt to obtain a professorship at Linz, in Austria; but the emperor would not consent to his leaving Prague, and encouraged him with hopes of payment of the arrears of his salary. On the death of Rudolph, Kepler again the form in which it appears in our modern treareceived the appointment of imperial mathemati-tises. The labor which Kepler bestowed on its cian, and was allowed to accept the chair at Linz. preparation was enormous; and it is curious to obHere he contracted his second marriage, and con- serve, that it was increased by the discovery of the tinued to reside during seven years, but with small logarithms; in consequence of which, he was unimprovement of his circumstances; for under der the necessity of giving a different form to seveMathias, the imperial finances appear to have been ral of the tables, in order to adapt them to the new in a still less flourishing state than under Rudolph; method of calculation. and Kepler, who depended mainly upon his pen- Kepler had continued to reside at Linz since sion for his means of living, suffered great vexa- 1622; but, about the time of the appearance of tion in consequence of its remaining unpaid. "In the "Rudolphine Tables," he was invited by the order," he says, "to defray the expense of the Duke of Friedland, a great patron of astrology, to Ephemeris for two years, I have been obliged to take up his abode at Sagan, in Silesia. Having compose a vile prophesying almanac, which is solicited permission from the emperor to accept of scarcely more respectable than begging, unless from this invitation, "the emperor did not hesitate to its saving the emperor's credit, who abandons me grant the request, and would gladly have transferentirely, and would suffer me to perish with hun-red Kepler's arrears as well as himself to the service ger." But the death of Mathias in 1619 gave of a foreign prince." Kepler accordingly removed him hopes of better times; for the new emperor, Ferdinand III., not only renewed his appointment, but promised to pay up all the arrears of his pension; and to furnish him besides with the means of accomplishing the great object of his ambition, the publication of the Rudolphine Tables. In 1622, Kepler published his Harmonices Mundi, a work filled with speculations on a great variety of subjects-geometry, music, astrology, astronomy, and metaphysics; but chiefly remarkable, as containing the announcement of the relation which subsists between the periodic times, and the mean distances of the planets. The beauty and extreme importance of this general law of the planetary system, is such as to render the burst of joy with which he announced it in no way extravagant :— "This law, as he himself informs us, first entered his mind on the 8th of March, 1618; but, having made an erroneous calculation, he was obliged to reject it. He resumed the subject on the 15th of May; and, having discovered his former error, recognized with transport the absolute truth of a principle which, for seventeen years, had been the object of his incessant labors. The delight which this grand discovery gave him had no bounds. Nothing holds me,' said he; 'I will indulge in my sacred fury; I will triumph over mankind by the honest confession that I have stolen the golden vases of the Egyptians to build up a tabernacle for my God, far away from the confines of Egypt. If you forgive me, I rejoice; if you are angry, I can bear it. The die is cast, the book is written, to be read either now or by posterity, I care not which. It may well wait a century for a reader, as God has waited six thousand years for an observer.'"-(p. 240.) The "Rudolphine Tables," in the preparation of which Kepler had been engaged for twenty-six years, after having been long delayed for want of funds to defray the expenses of the printing, and subsequently from the disturbed state of Germany during the wars of the reformation, were at length published in 1628. The work is remarkable in the history of astronomy, as containing the first tables which were calculated on the hypothesis of elliptic orbits, and as exhibiting the science under his family to Sagan in 1629, and was favorably received by the grand duke, who treated him with distinction and liberality, and procured for him a professorship in the University of Rostock. But it would seem as if no change had the power of producing any amelioration of Kepler's fortunes- "In this remote situation, Kepler found it extremely difficult to obtain payment of the imperial accumulated to 8000 crowns; and he resolved to pension, which he still retained. The arrears had go to the imperial assembly at Ratisbon to make a final effort to obtain them. His attempts, however, were fruitless. The vexation which this occasioned, and the great fatigue which he had is said to have been one of cold, and to have been undergone, threw him into a violent fever, which accompanied with an imposthume in the brain, baffled the skill of his physicians, and carried him occasioned by too much study. This disease off on the 5th of November, O. S., 1630, in the sixtieth [fifty-ninth] year of his age.”—(p. 249.) Kepler's name will always be associated with the discovery of the three laws which regulate the planetary motions; by which he effected a greater revolution in theoretical astronomy than ever had fallen, or can fall again, to the lot of any individual. But he has many other claims upon our consideration. The "Rudolphine Tables" were a most important contribution to practical astronomy, and would alone have sufficed to place him in the first rank among the promoters of that science; and various methods of observation and computation suggested by him are still in use. cal speculations, though frequently fanciful, and His physi sometimes extravagant, always give evidence of enlarged views and great acuteness; and he nearly anticipated two of Newton's most important discoveries-the law of gravitation, and the theory of the prismatic colors. In mathematics his knowledge was neither systematic nor very profound; and the circumstance was unfortunate for himself, for greater proficiency in this science would have saved him an immensity of unnecessary calculations. Nevertheless, even here he has left the impress of his genius. His method |