On Tycho’s Island: Tycho Brahe and His Assistants, 1570-1601 
by John Robert Christianson.
Cambridge, 451 pp., £30, March 2000, 9780521650816
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In Prague people still say: ‘I do not want to die like Tycho Brahe.’ This means: ‘I have to go to the lavatory.’ In this way the memory of the greatest astronomer of early modern Europe is daily refreshed. How the Danish nobleman Brahe or, rather, Tycho – his fame was so great in his time that, like Dante and Galileo, he is known in ours by his first name – came to expire of a burst bladder in Prague is explained, along with much else, by John Robert Christianson. The centre of gravity of Tycho’s Island is Danish social history: in irresistible detail, Christianson interprets Tycho’s behaviour in the context of the customs and expectations of the Danish high aristocracy.

Tycho’s island was Hven, in the sound off Elsinore, now a bit of Sweden but then a fief in the gift of the Danish Crown. Tycho became its lord in 1576. In return for the island, the income from other holdings and a share of the tolls charged to shipping through the sound, Tycho undertook to make his King, Frederick II, famous throughout Europe as a patron of the sciences. Tycho’s interests extended beyond astronomy and astrology, for which he had developed a passion as a student in Germany, to alchemy, the decorative arts, printing, and eating and drinking. He would make Hven not only a northern precinct of the muses, but also a fitting dwelling for a Brahe.

Tycho had grown up in castles, of which his immediate family owned several. Hven had no castle. Tycho therefore built one with the help of the islanders’ labour: his feudal rights allowed him to demand their services. Uraniborg, as he called his new home, had rooms for alchemical experiments and celestial observations, studies and a library, 14 chimneys and the usual domestic apartments. The castle stood at the centre of a square garden enclosed by walls 6 metres high, 78 metres long and 5 metres thick, and guarded by man-eating dogs. At a short distance from the castle Tycho built a satellite observatory stocked with instruments unique in their size and accuracy. Outbuildings contained a printing press, shops and servants’ quarters.

To run this establishment Tycho needed the islanders, a printer and a domestic staff to look after himself, his wife, their five children, and a fluctuating number of astronomers, chemists, mathematicians, noble guests and common visitors. Tycho must have had two dozen people to dinner every night he was at home. That was a heavy expense, but he recouped on the payroll. The islanders had to work for nothing and the observers – many of them students from the University of Copenhagen – followed the stars at night for no greater payment than breakfast and bed and Tycho’s conversation at dinner. More senior observers, who signed on for between six months and five years, received as well whatever Tycho was pleased to give them. Some had trouble escaping from the island when they rejected his terms of employment.

Christianson stresses that the observers, the printer, the pastor Tycho installed in the island’s church, the jester and other senior members of his establishment were an extension of Tycho’s family, and owed him loyalty in return for his beneficence. As for the family itself, it suffered as a result of the same ready passion that drove Tycho to undertake the first systematic and continuous observations of the stars and planets, as well as to fight a duel in Germany that cost him half his nose: he fell for a commoner, Kirsten Jørgensdatter. Although they never married in a church, Tycho and Kirsten were bound together as man and wife by customary law. Nonetheless, neither his wife nor his children could inherit his estates without a special dispensation from the Crown. Tycho spent much of his time trying to obtain this and an agreement that his sons could succeed him as lords of Hven. Frederick II died before signing the documents and his successor, Christian IV, refused to do so.

The new King, who was 19 when he was crowned in 1596, had visited Hven and been much impressed by the scale of Tycho’s operations. Perhaps too impressed. His advisers, playing on his susceptibilities, convinced him that the nobility had usurped power rightly belonging to the Crown. Tycho’s magnificent way of living and his refusal to honour his feudal commitments despite frequent royal admonitions made him a target. The islanders charged him with unfair exactions and a church court accused him of living in sin. Since he was too powerful to be brought down in this way, the court condemned his pastor for having allowed the sinning. The pastor spent a month in jail. The King repossessed about a third of the estates that his father had bestowed on Tycho.

The writing on the thick walls of Hven was clear. Tycho left the island in 1597 and set up in Copenhagen in a castle and observatory he had built near the university. He was hounded out. The municipal authorities would not allow him to use the observatory, which rested on the city wall. Tycho packed up his instruments, household belongings, cash, jewels and extended family – some twenty people including the lax pastor – and set off for Hamburg. There he found refuge in the castle of a Danish nobleman. His attempts to reinstate himself with King Christian via a haughty letter praising himself and claiming his due inevitably failed. He turned to Rudolf II, Holy Roman Emperor, astrologer, alchemist, collector and crackpot, for patronage. Rudolf agreed to an interview in Prague, which he had made the Imperial capital. Tycho gave the Emperor three of his works bound in silk and came away with what he needed to establish his astronomical programme in Prague. But at one particularly lengthy bout of eating and drinking, he remained at table, unwilling to rise before his host, until his bladder burst. He died five days later, on 24 October 1601. Although he had not regained Uraniborg, he had obtained from Rudolf something he prized as much: his wife and children were accorded noble status. His sons lived as Bohemian squires. His youngest daughter married a baron; the middle daughter, an important Hapsburg diplomat; the eldest, no one, having been jilted by one of Tycho’s students. Tycho spent much of his last years in Denmark trying to prove the malfeasance of this suitor, and Christianson devotes a proportionate number of pages to his unsuccessful campaign.

Christianson’s is the first biography of Tycho in English to take as its subject the running of Hven, Tycho’s relationships with the Danish nobility and the identities of the visitors and residents of Uraniborg. The last third of his book provides a biographical register of Tycho’s assistants, and lists their future careers as clergymen, administrators, bishops, professors, physicians and so on. Readers wanting to know why Tycho deserved and deserves the admiration of astronomers should turn to Victor Thoren’s The Lord of Uraniborg: A Biography of Tycho Brahe (1990) or to J.L.E. Dreyer’s Tycho Brahe: A Picture of Scientific Life and Work in the 16th Century (1890, reprinted 1977). What made Tycho a world-historical figure was his involuntary exile to Prague. There his great registers of observations fell into the hands of a man uniquely prepared to exploit them. He was Johannes Kepler, a Protestant teacher of mathematics who had been driven from his school in Catholic Austria. Kepler had published one book, the Mysterium cosmographicum (1596), which, with his usual openness, he announced as the finest first work ever written. He sent Tycho a copy. Just by flipping the pages Tycho could see that Kepler was a vigorous and resourceful mathematician and a whimsical cosmologist.

Kepler had discovered that God had been thinking about the five Platonic solids – the equilateral pyramid, the cube, and analogous structures with 8, 12 and 20 faces – when placing the planets around the Sun (Kepler was a Copernican). Kepler could read God’s calculations as easily as he could check a laundry bill. To Tycho, however, the interesting fact about Kepler was not that he knew the secret of the Universe but that he was unemployed. Kepler joined Tycho’s extended family as a mathematician. He was ordered to deduce from the Hven observations the system of circles supposed to carry the planets around the Sun (or the Earth). He worked under Tycho for ten months before the Imperial Mathematician’s last drinking bout. Kepler succeeded to Tycho’s post and also to his registers, and continued the project he had been assigned. After several years of fighting with Mars, Kepler gave it up. He could neither discard the Hven observations – they were too good and too plentiful – nor fit them to circles. In his frustration he discovered or (to speak in the language of historians of science) invented the elliptical paths of the planets. These and two other key ‘laws’ worked out by Kepler later helped Newton to unlock the cosmic mystery.

Tycho himself did not willingly abandon anything, including the making of world systems, to anyone. He flirted with Copernican geometry but finally gave it up for philosophical and theological reasons. To secure its advantages without the perceived blemishes, Tycho supposed that all the planets circle the Sun and that the Sun with its brood circles the Earth. This ‘Tychonic system’ had a long life. Its compromising character recommended it to the Jesuits, who taught it well into the 18th century. It provided a convenient haven for them and for lay astronomers when, as a result of its dispute with Galileo, the Catholic Church condemned Copernican theory as contrary to scripture and absurd in philosophy.

It is tempting to compare Hven – with its parade of Danish, Dutch and German students, its staff of senior observers, its up-to-date equipment, its schedule of observations, its director always seeking financial support – to a modern international research institute. Christianson yields to this temptation and in doing so commits the sin of anachronism. Uraniborg was Tycho’s fief. All the instruments and all the data belonged to him. He printed the results, his results, when it pleased him to do so, which was not often. Staff and students would have had no means of publishing their work independently (there were no scientific journals) even if they’d considered it. Most of them aimed at a career in medicine or the Church or the service of a prince; they were not ‘scientists’, as Christianson often calls them, but assistants and even servants in a noble household. There was peer review only in a Pickwickian sense: Tycho stayed in Hven as long as his equals in the high nobility supported his position and the King accepted their views.

Tycho’s enterprise was unique. It had the virtues and failings of its creator and no competitors to serve as models, goads or constraints. Tycho’s contemporary and sometime correspondent John Dee was also a mathematician, astronomer, alchemist, book collector and egotist. Again like Tycho, he advised his sovereign, in his case Elizabeth I, on astrological matters, and also on such down-to-earth questions as whether to invest in voyages of exploration and how to provide timber for the British Navy; and he outlined a course of astronomical and astrological observations and calculations that would have taken ten Tychos to complete. Dee, who also spent some time at the court of Rudolf II, did not have Tycho’s patience, however, and attempted to instruct himself by interviewing angels. He developed a language and hired a scryer for the purpose. Had Elizabeth supplied all the money he said he needed, Dee would have been able to set up an Institute for Astrological, Alchemical and Angelic Research, with divisions for planetary talismans, celestial languages, forestry, navigation and marine insurance. Like Uraniborg, Dee’s museum would have been a reflection of its creator’s fancy at a time when the pursuit of natural knowledge was ad hoc and idiosyncratic, and the idea of a scientific career had not occurred to anyone.

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