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KEPLER, JOHANN (1571-1630)

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Originally appearing in Volume V15, Page 751 of the 1911 Encyclopedia Britannica.
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KEPLER, JOHANN (1571-1630) , See also:German astronomer, was See also:born on the 27th of See also:December 1571, at Weil, in the duchy of See also:Wurttemberg, of which See also:town his grandfather was burgomaster. Ile was the eldest See also:child of an See also:ill-assorted See also:union. His See also:father, See also:Henry Kepler, was a reckless soldier of See also:fortune; his See also:mother, See also:Catherine Guldenmann, the daughter of the burgomaster of Eltingen, was undisciplined and ill-educated. Her See also:husband found campaigning in See also:Flanders under See also:Alva a welcome See also:relief from domestic See also:life; and, after having lost all he possessed by a forfeited See also:security and tried without success the See also:trade of See also:tavern-keeping inthe See also:village of Elmendingen, he finally, in 1589, deserted his See also:family. The misfortune and misconduct of his parents were not the only troubles of Kepler's childhood. He recovered from small-pox in his See also:fourth See also:year with crippled hands and eyesight permanently impaired; and a constitution enfeebled by premature See also:birth had to withstand successive shocks of severe illness. His schooling began at Leonberg in 1577—the year, as he himself tells us, of a See also:great See also:comet; but domestic See also:bankruptcy occasioned his transference to See also:field-See also:work, in which he was exclusively employed for several years. Bodily infirmity, combined with See also:mental aptitude, were eventually considered to indicate a theological vocation; he was, in 1584, placed at the See also:seminary of Adelberg, and thence removed, two years later, to that of Maulbronn. A brilliant examination for the degree of See also:bachelor procured him, in 1588, admittance on the See also:foundation to the university of See also:Tubingen; Where he laid up a copious See also:store of classical erudition, and imbibed Copernican principles from the private instructions of his teacher and life-See also:long friend, See also:Michael Maestlin. As yet, however, he had little knowledge of, and less inclination for, See also:astronomy; and it was with extreme reluctance that he turned aside from the more promising career of the See also:ministry to accept, See also:early in 1594, the vacant See also:chair of that See also:science at Gratz, placed at the disposal of the Tubingen professors by the Lutheran states of See also:Styria. The best recognized See also:function of German astronomers in that See also:day was the construction of prophesying almanacs, greedily bought by a credulous public. Kepler thus found that the first duties required of -him were of an astrological nature, and set himself with characteristic alacrity to See also:master the rules of the See also:art as laid down by See also:Ptolemy and See also:Cardan.

He, moreover; sought in the events of his own life a verification of the theory of planetary influences; and it is to this practice that we owe the See also:

summary See also:record of each year's occurrences which, continued almost to his See also:death, affords for his See also:biography a slight but sure foundation. But his thoughts were already working in a higher See also:sphere. He early attained to the settled conviction that for the actual disposition of the See also:solar See also:system some abstract intelligible See also:reason must exist, and this, after much meditation, he believed himself to have found in an imaginary relation between the " five See also:regular solids " and the number and distances of the See also:planets. He notes with exultation the 9th of See also:July 1595, as the date of the pseudo-See also:discovery, the publication of which in Prodromus Dissertationum Cosmographicarum seu Mysterium Cosmographicum (Tubingen, 1596) procured him much fame, and a friendly See also:correspondence with the two most eminent astronomers of the See also:time, Tycho See also:Brahe and Galileo. Soon after his arrival at Gratz, Kepler contracted an engagement with See also:Barbara von Muhleck, a wealthy Styrian heiress, who, at the See also:age of twenty-three, had already survived one husband and been divorced from another. Before her relatives could be brought to countenance his pretensions, Kepler was obliged to undertake a See also:journey to Wurttemberg to obtain documentary See also:evidence of the somewhat obscure See also:nobility of his family, and it was thus not until the 27th of See also:April 1597 that the See also:marriage was celebrated. In the following year the See also:archduke See also:Ferdinand, on assuming the See also:government of his hereditary dominions, issued an See also:edict of banishment against See also:Protestant preachers and professors. Kepler immediately fled to the Hungarian frontier, but, by the favour of the See also:Jesuits, was recalled and reinstated in his See also:post. The gymnasium, however, was deserted; the nobles of Styria began to murmur at subsidizing a teacher without pupils; and he found it prudent to look elsewhere for employment. His refusal to subscribe unconditionally to the rigid See also:formula of belief adopted by the theologians of Tubingen permanently closed against him the See also:gates of his See also:alma mater. His embarrassment was relieved however by an offer from Tycho Brahe of the position of assistant in his See also:observatory near See also:Prague, which, after a preliminary visit of four months, he accepted. The arrangement was made just in time; for in See also:August 1600 he received definitive See also:notice to leave Gratz, and, having leased his wife's See also:property, he departed with his family for Prague.

By Tycho's unexpected death (Oct. 24, 1601) a brilliant career seemed to be thrown open to Kepler. The See also:

emperor See also:Rudolph II. immediately appointed him to succeed his See also:patron as imperial mathematician, although at a reduced See also:salary of 500 florins; the invaluable treasure of Tycho's observations was placed at his disposal; and the laborious but congenial task was entrusted to him of completing the tables to which the grateful Dane had already affixed the See also:title of Rudolphine. The first See also:works executed by him at Prague were, nevertheless, a See also:homage to the astrological proclivities of the emperor. In De fundamentis astrologiae certioribus (Prague, 1602) he declared his purpose of preserving and purifying the See also:grain of truth which he believed the science to contain. Indeed, the See also:doctrine of "aspects" and "influences" fitted excellently with his mystical conception of the universe, and enabled him to See also:discharge with a semblance of sincerity the most lucrative See also:part of his professional duties. Although he strictly limited his prophetic pretensions to the estimate of tendencies and probabilities, his forecasts were none the less in demand. Shrewd sense and considerable knowledge of the See also:world came to the aid of stellar See also:lore in the preparation of " prognostics " which, not unfrequently hitting off the event, earned him as much See also:credit with the vulgar as his cosmical speculations with the learned. He See also:drew the horoscopes of the emperor and See also:Wallenstein, as well as of a See also:host of lesser magnates; but, though keenly alive to the unworthy See also:character of such a trade, he made See also:necessity his excuse for a See also:compromise with superstition. " Nature," he wrote, " which has conferred upon every See also:animal the means of subsistence, has given See also:astrology as an See also:adjunct and ally to astronomy." He dedicated to the emperor in 1603 a .See also:treatise on the " great See also:conjunction" of that year (Judicium de trigono igneo); and he published his observations on a brilliant See also:star which appeared suddenly (See also:Sept. 30, 1604), and remained visible for seventeen months, in De stella nova in pede Serpentarii (Prague, 16o6).

While sharing the See also:

opinion of Tycho as to the origin of such bodies by condensation of nebulous See also:matter from the Milky Way, he attached a mystical signification to the coincidence in time and See also:place of the sidereal apparition with a triple conjunction of See also:Mars, See also:Jupiter and See also:Saturn. The See also:main task of his life was not meanwhile neglected. This was nothing less than the foundation of a new astronomy, in which See also:physical cause should replace arbitrary See also:hypothesis. A preliminary study of See also:optics led to the publication, in 1604, of his Astronomiae pars optica, containing important discoveries in the theory of See also:vision, and a notable approximation towards the true See also:law of See also:refraction. But it was not until 1609 that, the " great Martian labour " being at length completed, he was able, in his own figurative See also:language, to See also:lead the See also:captive See also:planet to the See also:foot of the imperial See also:throne. From the time of his first introduction to Tycho he had devoted himself to the investigation of the See also:orbit of Mars, which, on See also:account of its relatively large eccentricity, had always been especially recalcitrant to theory, and the results appeared in Astronomia nova airLoXoyorbs, seu Physica coelestis tradita commentariis de motibus stellae Martis (Prague, 1609). In this, the most memorable of Kepler's multifarious writings, two of the See also:cardinal principles of See also:modern astronomy—the See also:laws of elliptical orbits and of equal areas—were established (see ASTRONOMY: See also:History); important truths See also:relating to gravity were enunciated, and the tides ascribed to the See also:influence of lunar attraction; while an See also:attempt to explain the planetary revolutions in the then backward See also:condition of See also:mechanical knowledge produced a theory of vortices closely resembling that afterwards adopted by See also:Descartes. Having been provided, in August 1610, by Ernest, See also:archbishop of See also:Cologne, with one of the new Galilean See also:instruments, Kepler began, with unspeakable delight, to observe the wonders revealed by it. He had welcomed with a little See also:essay called Dissertatio cum See also:Nuncio Sidereo Galileo's first announcement of See also:celestial novelties; he now, in his Dioptrice (See also:Augsburg, 1611), expounded the theory of refraction by lenses, and suggested the principle of the " astronomical " or inverting See also:telescope. Indeed the work may be said to have founded the See also:branch of science to which it gave its name. The year 1611 was marked by Kepler as the most disastrous of his life. The death by small-pox of his favourite child was followed by that of his wife, who, long a See also:prey to See also:melancholy, was on the3rd of July carried off by typhus.

Public calamity was added to private bereavement. On the 23rd of May 1611 See also:

Matthias, See also:brother of the emperor, assumed the Bohemian See also:crown in Prague, compelling Rudolph to take See also:refuge in the citadel, where he died on the loth of See also:January following. Kepler's fidelity in remaining with him to the last did not deprive him of the favour of his successor. Payments of arrears, now amounting to upwards of 4000 florins, was not, however, in the desperate condition of the imperial finances, to be hoped for; and he was glad, while retaining his position as See also:court astronomer, to accept (in 1612) the See also:office of mathematician to the states of Upper See also:Austria. His See also:residence at See also:Linz was troubled by the harsh conduct of the pastor Hitzler, in excluding him from the See also:rites of his See also:church on the ground of supposed Calvinistic leanings—a decision confirmed, with the addition of an insulting reprimand, on his See also:appeal to Wurttemberg. In 1613 he appeared with the emperor Matthias before the See also:diet of Ratisbon as the See also:advocate of the introduction into See also:Germany of the Gregorian See also:calendar; but the attempt was for the time frustrated by See also:anti-papal See also:prejudice. The See also:attention devoted by him to See also:chronological subjects is evidenced by the publication about this See also:period of several essays in which he sought to prove that the birth of See also:Christ took place five years earlier than the commonly accepted date. Kepler's second courtship forms the subject of a highly characteristic See also:letter addressed by him to See also:Baron Stralendorf, in which he reviews the qualifications of eleven candidates for his See also:hand, and explains the reasons which decided his choice in favour of a portionless See also:orphan girl named Susanna Reutlinger. The marriage was celebrated at Linz, on the 3oth of See also:October 1613, and seems to have proved a happy and suitable one. The abundant vintage of that year drew his attention to the defective methods in use for estimating the cubical contents of vessels, and his essay on the subject (Nova Stereometria Doliorum, Linz, 1615) entitles him to See also:rank among those who prepared the discovery of the infinitesimal calculus. His observations on the three comets of 1618 were published in De Cometis, contemporaneously with De Harmonice Mundi (Augsburg, 1619), of which the first lineaments had been traced twenty years previously at Gratz. This extraordinary See also:production is memorable as having announced the discovery of the " third law "—that of the sesquiplicate ratio between the planetary periods and distances.

But the main purport of the treatise was the exposition of an elaborate system of celestial harmonies depending on the various and varying velocities of the several planets, of which the sentient soul animating the See also:

sun was the solitary auditor. The work exhibiting this fantastic emulation of extravagance with See also:genius was dedicated to See also:James I. of See also:England, and the compliment was acknowledged with an invitation to that See also:island, conveyed through See also:Sir Henry See also:Wotton. Notwithstanding the distracted See also:state of his own See also:country, he refused to abandon it, as he -had previously, in 1617, declined the post of successor to G. A. Magini in the mathematical chair of See also:Bologna. The insurmountable difficulties presented by the lunar theory forced Kepler, after an enormous amount of fruitless labour, to abandon his See also:design of comprehending the whole See also:scheme of the heavens in one great work to be called See also:Hipparchus, and he then threw a portion of his materials into the See also:form of a See also:dialogue intended for the instruction of See also:general readers. The See also:Epitome Astronomiae Copernicanae (Linz and See also:Frankfort, 1618-1621), a lucid and attractive textbook of Copernican science,was remark-able for the prominence given to " physical astronomy," as well as for the See also:extension to the See also:Jovian system of the laws recently discovered to regulate the motions of the planets. The first of a See also:series of ephemerides, calculated on these principles, was published by him at Linz in 1617; and in that for 1620, dedicated to Baron See also:Napier, he for the first time employed logarithms. This important invention was eagerly welcomed by him, and its theory formed the subject of a treatise entitled Chilias Logarithmorum, printed in 1624, but circulated in See also:manuscript three years earlier, which largely contributed to bring the new method into general use in Germany. His studies were interrupted by family trouble. The restless disposition and unbridled See also:tongue of Catherine Kepler, his mother, the sphere of the fixed stars, and the intermediate space, filled with created for her numerous enemies in the little town of Leonberg; while her unguarded conduct exposed her to a See also:species of calumny at that time readily circulated and believed. As early as 1615 suspicions of sorcery began to be spread against her, which she, with more spirit than prudence, met with an See also:action for See also:libel.

The suit was purposely protracted, and at length, in 1620, the unhappy woman, then in her seventy-fourth year, was arrested on a formal See also:

charge of See also:witchcraft. Kepler immediately hastened to Wurttemberg, and owing to his indefatigable exertions she was acquitted after having suffered thirteen See also:month's imprisonment, and endured with undaunted courage the formidable See also:ordeal of " territion," or examination under the imminent See also:threat of See also:torture. She survived her See also:release only a few months, dying on the 13th of April 1622. Kepler's whole attention was now devoted to the production of the new tables. " Germany," he wrote, " does not long for See also:peace more anxiously than I do for their publication." But See also:financial difficulties, combined with See also:civil and religious See also:convulsions, long delayed the accomplishment of his desires. From the 24th of See also:June to the 29th of August 1626, Linz was besieged, and its inhabitants reduced to the utmost straits by bands of insurgent peasants. The pursuit of science needed a more tranquil shelter; and on the raising of the See also:blockade, Kepler obtained per-See also:mission to See also:transfer his types to See also:Ulm, where, in See also:September 1627, the Rudolphine Tables were at length given to the world. Although by no means See also:free from errors, their value appears from the fact that they ranked for a See also:century as the best aid to astronomy. Appended were tables of logarithms and of refraction, together with Tycho's See also:catalogue of 777 stars, enlarged by Kepler to 1005. Kepler's claims upon the insolvent imperial See also:exchequer amounted by this time to 12,000 florins. The emperor Ferdinand II., too happy to transfer the See also:burden, countenanced an arrangement by which Kepler entered the service of the See also:duke of See also:Friedland (Wallenstein), who assumed the full responsibility of the See also:debt. In July 1628 Kepler accordingly arrived with his family at See also:Sagan in See also:Silesia, where he applied himself to the See also:printing of his ephemerides up to the year 1636, and whence he issued, in 1629, a Notice to the Curious in Things Celestial, warning astronomers of approaching transits.

That of See also:

Mercury was actually seen by Gassendi in See also:Paris on the 7th of See also:November 1631 (being the first passage of a planet across the sun ever observed); that of See also:Venus, predicted for the 6th of December following, was invisible in western See also:Europe. Wallenstein's promises to Kepler were but imperfectly fulfilled. In lieu of the sums due, he offered him a professorship at See also:Rostock, which Kepler declined. An expedition to Ratisbon, undertaken for the purpose of representing his See also:case to the diet, terminated his life. Shaken by the journey, which he had performed entirely on horseback, he was attacked with See also:fever, and died at Ratisbon, on the 15th of November (N.S.), 1630, in the fifty-ninth year of his age. An See also:inventory of his effects showed him to have been possessed of no inconsiderable property at the time of his death. By his first wife he had five, and by his second seven See also:children, of whom only two, a son and a daughter, reached maturity. The character of Kepler's genius is especially difficult to estimate. His tendency towards mystical See also:speculation formed a not less fundamental quality of his mind than its strong grasp of See also:positive scientific truth. Without assigning to each See also:element its due value, no See also:sound comprehension of his modes of thought can be attained. His See also:idea of the universe was essentially See also:Pythagorean and Platonic. He started with the conviction that the arrangement of its parts must correspond with certain abstract conceptions of the beautiful and harmonious.

His See also:

imagination, thus kindled, animated him to those severe labours of which his great discoveries were the See also:fruit. His demonstration that the planes of all the planetary orbits pass through the centre of the sun, coupled with his clear recognition of the sun as the moving See also:power of the system, entitles him to rank as the founder of physical astronomy. But the fantastic relations imagined by him of planetary movements and distances to musical intervals and geometrical constructions seemed to himself discoveries no less admirable than the achievements which have secured his lasting fame. Outside the boundaries of the solar system, the metaphysical See also:side of his genius, no longer held in check by experience, fully asserted itself. The Keplerian like the Pythagorean cosmos was threefold, consisting of the centre, or sun, the See also:surface, represented by ethereal matter. It is a See also:mistake to suppose that he regarded the stars as so many suns. He quotes indeed the opinion of See also:Giordano See also:Bruno to that effect, but with dissent. Among his happy conjectures may be mentioned that of the sun's axial rotation, postulated by him as the physical cause of the revolutions of the planets, and soon after confirmed by the discovery of sun-spots; the See also:suggestion of a periodical variation in the obliquity of the See also:ecliptic; and the explanation as a solar atmospheric effect of the radiance observed to surround the totally eclipsed sun. It is impossible to consider without surprise the See also:colossal amount of work accomplished by Kepler under numerous disadvantages. But his See also:iron See also:industry counted no obstacles, and secured for him the highest See also:triumph of genius, that of having given to mankind the best that was in him. In private character he was amiable and affectionate; his generosity in recognizing the merits of others secured him against the worst shafts of envy; and a life marked by numerous disquietudes was cheered and ennobled by sentiments of sincere piety. Kepler's extensive See also:literary remains, See also:purchased by the empress Catherine II. in 1724 from some Frankfort merchants, and long inaccessibly deposited in the observatory of Pulkowa, were fully brought to See also:light, under the able editorship of Dr Ch.

Frisch, in the first See also:

complete edition of his works. This important publication (Joannis Kepleri See also:opera amnia, Frankfort, 1858-1871, 8 vols. 8vo) contains, besides the works already enumerated and several See also:minor See also:treatises, a See also:posthumous scientific See also:satire entitled Jolt. Keppleri Somnium (first printed in 1634) and a vast See also:mass of his correspondence. A careful biography is appended, founded mainly on his private notes and other See also:authentic documents. His correspondence with Herwart von Hohenburg, unearthed by C. Anschiitz at See also:Munich, was printed at Prague in 1886. AUTHORITIES—C. G. Reuschle, Kepler and See also:die Astronomic (See also:Frank-fort, 1871); Karl Goebel, Ober Keplers astronomische Anschauungen (See also:Halle, 1871) ; E. F. Apelt, Johann Keplers astronomische Weltansicht (See also:Leipzig, 1849) ; J.

L. C. Breitschwert, Johann Keplers Leben and Wirken (See also:

Stuttgart, 1831) ; W. See also:Forster, Johann Kepler and die Harmonie der Sphdren (See also:Berlin, 1862) ; R. See also:Wolf, Geschichte der Astronomic (Munich, 1877); J. von Hasner, Tycho Brahe and J. Kepler in See also:Brag (1872); H. Brocard, Essai sur la Meteorologie de Kepler (See also:Grenoble, 1879, 1881) ; Siegmund See also:Gunther, Johannes Kepler 'and der tellurischkosmische Magnetismus (Wien, 1888); N. Herz, Keplers Astrologie (1895) ; See also:Ludwig Gunther, Keplers Traum vam See also:Mond (1898 ; an annotated See also:translation of the Somnium); A. See also:Muller, Johann Keppler, der Gesetzgeber der neueren Astronomic (1903); Allgemeine Deutsche Biographic, Bd. XV. (1882). (A.

M.

End of Article: KEPLER, JOHANN (1571-1630)

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