The Rudolphine Tables were published at Ulm in one volume folio. These Tables were calculated by Kepler from the Observations of Tycho, and are founded on his own great discovery of the ellipticity of the planetary orbits. The first and third parts of the work contain logarithmic and other auxiliary tables, for the purpose of facilitating astronomical calculations. The second part contains tables of the sun, moon, and planets; and the fourth a catalogue of 1000 stars, as determined by Tycho. A nautical map is prefixed to some copies of the tables, and the description of it contains the first notice of the method of determining the longitude by means of occultations.
A short time after the publication of these tables, the Grand Duke of Tuscany, instigated no doubt by Galileo, sent Kepler a gold chain in testimony of his approbation of the great service which he had rendered to astronomy.
About this time Albert Wallenstein, Duke of Friedland, a great patron of astrology, and one of the most distinguished men of the age, made the most munificent offers to Kepler, and invited him to take up his residence at Sagan in Silesia. The religious dissensions which agitated Linz, the love of tranquillity which Kepler had so little enjoyed, and the publication of his great work, induced him to accept of this offer. He accordingly removed his family from Linz to Ratisbon in 1629, and he himself set out for Prague, with the double object of presenting the Rudolphine Tables to the Emperor, and of soliciting his permission to go into the service of the Duke of Friedland. The Emperor did not hesitate to grant this request; and would have gladly transferred Kepler’s arrears as well as himself to the charge of a foreign prince. Kepler accordingly set out with his wife and family for Sagan, where he arrived in 1629. The Duke Albert treated him with liberality and distinction. He supplied him with an assistant for his calculations, and also with a printing press; and, by his influence with the Duke of Mecklenburg, he obtained for him a professorship in the University of Rostoch.
In this remote situation, Kepler found it extremely difficult to obtain payment of the imperial pension which he still retained. The arrears had accumulated to 8000 crowns, and he resolved to 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 undergone, threw him into a violent fever, which is said to have been one of cold, and to have been accompanied with an imposthume in his brain, occasioned by too much study. This disease baffled the skill of his physicians, and carried him off on the 5th November, O.S. 1630, in the sixtieth year of his age.
The remains of this great man were interred in St Peter’s Churchyard at Ratisbon, and the following inscription, embodying an epitaph which he had written for himself, was engraven on his tombstone.
In hoc quiescit vir nobilissimus, doctissimus et celeberrimus Dom. Johannes Keplerus, trium Imperatorum Rudolphi II., Mathiæ, et Ferdinandi II., per annos XXX, antea vero procerum Styriæ ab anno 1594 usque 1600, postea quoque astriacorum ordinum ab anno 1612 usque ad annum 1628, Mathematicus toti orbi Christiani, per monumenta publica cognitus, ab omnibus doctis, inter Principes Astronomiæ numeratus, qui propria manu assignatum post se reliquit tale Epitaphium.
Mensus eram cœlos, nunc terræ metior umbras:
Mens cœlestis erat, corporis umbra jacet.
In Christo pie obiit anno Salutis 1630, die 5 Novembris, ætatis suæ sexagesimo.
This monument was not long preserved. It was destroyed during the wars which desolated Germany; and no attempt was made till 1786 to mark with honour the spot which contained such venerable remains. This attempt, however, failed, and it was not till 1803 that this great duty was paid to the memory of Kepler, by the Prince Bishop of Constance, who erected a handsome monumental temple near the place of his interment, and in the Botanical Garden of the city. The temple is surmounted by a sphere, and in the centre is a bust of Kepler in Carrara marble.
Kepler left behind him a wife and seven children—two by his first wife, Susanna and Louis; and three sons and two daughters by his second wife, viz.—Sebald, Cordelia, Friedman, Hildebert, and Anna Maria. The eldest of these, Susanna, was married a few months before her father’s death to Jacob Bartschius, his pupil, who was educated as a physician; and his son Louis died in 1663, while practising medicine at Konigsberg. The children by his second wife are said to have died young. They were left in very narrow circumstances; and though 24,000 florins were due to Kepler by the Emperor, yet only a part of this sum was received by Susanna, in consequence of her refusing to give up Tycho’s Observations till the debt was paid. Kepler composed a little work entitled “The Dream of John Kepler, or Lunar Astronomy,” the object of which was to describe the phenomena seen from the moon; but he died while he and Bartschius were engaged in its publication, and Bartschius having resumed the task, died also before its completion. Louis Kepler dreaded to meddle with a work which had proved so fatal to his father and his brother-in-law, but this superstitious feeling was overcome, and the work was published at Frankfort in 1636.