Tycho and Kepler

by Kitty Ferguson

  Two days later, December 29, Tycho’s astrological computations told him that there would be some sort of accidental happening. In spite of the fact that one of his predictions of late had been notoriously inaccurate, he decided to take the warning seriously and not go out at all that day. However, when evening fell, he ventured downstairs in his lodging house to supper. Before long he and Parsberg were quarreling again, wrought up, each demanding that the other draw his sword.7 They rose abruptly from the table and went out into the churchyard.

  A woman in the room knew Danish and understood the seriousness of the dispute. She urged other diners to pursue the young men and prevent their damaging or murdering one another. It was too late. The company emerging from the dining room found a bloody scene. A blow from Parsberg’s broadsword had cut away a good portion of Tycho’s nose and just missed proving fatal. Later portraits show a diagonal scar across Tycho’s forehead and a curving line across the bridge of his nose. Tycho endured a lengthy, painful, and anxious period of convalescence that winter. His doctors couldn’t reverse the disfigurement, for skin grafting, though done in other parts of the world, was unknown in Europe until about two decades later.fn2 Fortunately, infection did not set in, and sufficient scar tissue formed.

  Although Tycho lost part of his nose at Rostock, he gained two new interests that remained with him for the rest of his life: medicine and alchemy. When he returned to Denmark in April, he was already experimenting with ways to replace his nose artificially. Later descriptions indicate that eventually, with fair success, he made a false nose by blending gold and silver to a flesh color, or used copper for everyday wear. He held the nose in place with an adhesive salve that he always carried with him in a small box.

  When Tycho left Denmark for the Continent a third time, the next December (1567), he did so over much stronger protests from his father. The war had offered a superb opportunity to begin a political career, which Tycho had ignored. Now the steady recovery of Peder Oxe’s influence made success for Tycho, as foster son of Peder’s sister, a certainty, if Tycho would only be persuaded to enter public life. Tycho had come of age when he turned twenty-one earlier that December, but that didn’t leave him free to flout his father’s will, for he was still dependent on him for financial support. Tycho had just missed inheriting his uncle’s fortune, and it was doubtful that he would be able to earn a living in the pursuits he was choosing. Nevertheless, to Otte Brahe’s intense frustration, his eldest son turned his back again on a promising future and headed across the Baltic to Rostock.

  Though modern popular opinion might have it that in earlier centuries an aristocrat had unlimited opportunity, while the lower classes were sadly constrained in their career choices, the fact is that in the Europe of Tycho’s day a nobleman’s son was fairly strictly limited to the career paths that Tycho’s forebears and relatives took—knighthood, the administration of fiefs, or government civil service. Tycho enjoyed university life, but there was no future in that, for most scholarly positions in the universities were closed to noblemen.

  There was, however, another possibility: a canonry. The cathedrals in Denmark and Norway—having recently become Lutheran—still retained their rich landed endowments. Royal administrators awarded the positions of canons of the chapters of these cathedrals both to government servants and to men of learning. Commoners and noblemen alike were eligible for a canonry, which carried with it the income from the endowment. Becoming a Lutheran canon did not require a man to enter holy orders, live in the cathedral precincts, or assume a less secular lifestyle. It was the ideal solution for someone who wanted to have a career as an astronomer and a scholar while upholding tradition and retaining his dignity as a member of the nobility, without trespassing on the career opportunities of men of another class of society. There was an excellent precedent, for Nicolaus Copernicus had been a canon of a cathedral chapter.

  Hence, while Tycho was returning to foreign climes, heedless of the future, his more sober friends and relatives at court, who included the influential Peder Oxe, set to work to procure a canonry for him. On May 14, 1568, royal letters patent designated Tycho to take up the next vacant canonry at Roskilde Cathedral. The position was reserved for him, though he had to wait for an opening. Although he could not know it had happened, there had been a minuscule tightening of the cords that would draw him over the next thirty-two years to that February day at Benatky when Johannes Kepler arrived.

  Meanwhile, Tycho’s lodgings in the law college at Rostock were providing an excellent setting for astronomical observations, and he was also finding time for his new interest in medical alchemy. But when university authorities charged him a hefty fine, possibly because of the duel with Parsberg, Tycho left rather than pay it and traveled south. At Arnstadt there was to be a ceremony in which Count Günther of Schwarzburg-Rudolstadt presented Tycho’s younger brother Steen with his spurs, a warhorse, and a harness of armor. Steen’s training had taken the traditional path, and he was now well ahead of Tycho on that path.

  By September, Tycho’s meanderings across Europe had taken him to Basel, and there he matriculated at yet another university. After a few months he moved on to Freiburg, where he was impressed by some celestial models demonstrating planetary motions according to the theories of Ptolemy and Copernicus.

  As Tycho’s restlessness and his travels continued, he gradually came to realize that after nine years of university he had learned all he could from professors and books. It was time to embark on more independent work, to direct his own life and education, and especially to experiment with the design and construction of his own observing instruments. His cross staff, even though it was one of the best available and he had found ways to compensate for some of its deficiencies, had long ago proved inadequate to Tycho’s needs.

  In spring 1569 Tycho’s travels brought him to the fine old imperial city of Augsburg, and he found it so much more congenial than any of the other cities he had visited that he stayed for fourteen months. It was in Augsburg that he began to follow through seriously on the plans to improve his instruments.

  His first project was to fashion a new pair of compasses.9 fn3 Such an instrument was used to measure the angular distance (see appendix 1) between stars, or between a planet or comet and stars near it in the night sky. Tycho wrote of an earlier, more primitive version that he used it by “placing the vertex10 close to my eye and directing one of the legs toward the planet to be observed and the other toward some fixed star near it.” Though the new pair of compasses was a good enough instrument for Tycho to include it in the catalog of his instrumental achievements twenty-five years later, it was not completely satisfactory. One problem was that he could not manage to mount it in such a way as to allow exact, steady sighting. Another was that Tycho had set himself a goal of accuracy to a minute of arc. The smallest division on the compasses was one degree of arc; a minute of arc is one-sixtieth of a degree of arc. To approach the precision Tycho wanted, it would be necessary to have an instrument large enough to include the device called “transversal points” he had learned about from Bartholomew Schultz in Leipzig. Meanwhile, as he had done earlier for the cross staff, Tycho drew up a table of corrections.

  Not long after his arrival in Augsburg, Tycho was lingering in front of a shop, conversing about the challenge of building an instrument of sufficient size, when a wealthy alderman of the city, Paul Hainzel, chanced by, overheard the discussion, and enthusiastically joined in. Hainzel and Tycho soon discovered that they had a connection. Hainzel’s brother had once been a fellow student with Peder Oxe. So intrigued did Hainzel become with Tycho’s instrument project that he offered to underwrite the cost of it.

  Tycho, who by now had a good idea of the instrument he wanted, set to work on the design and engaged the necessary craftsmen. The quadrans maximus,11 or “great quadrant,” was completed in a month, and it was the largest instrument Tycho would ever design—indeed, that he would ever see—twenty feet high and requiring forty men to set it
in place in the grounds of Hainzel’s estate just outside Augsburg. Tycho boasted about its accuracy, but it had problems. Tycho made only one entry in his log each night, perhaps because it required so many of Hainzel’s servants to rotate the cumbersome quadrant into the necessary plane and swing the arc up to the appropriate elevation. They had to keep it there while more adjusting brought the planet being observed into the sights. Only then could the numbers where the plumb line fell be written down, giving the altitudefn4 of the planet above the horizon. Sleepy retainers, no matter how loyal to Hainzel, could not be expected to perform this operation more than once a night without rebellion.

  Figure 2.2: The quadrans maximus that Tycho designed and had constructed in Paul Hainzel’s garden near Augsburg was built mostly of oak, with brass for the graduation strip on the arc and the plumb bob. The length along one edge (from C to G, for example) measured more than fifteen feet. The entire triangular section hung from its point at the top, allowing it to be swung up until Tycho could see the heavenly body through both the sights (D and E) at once and note at what number the plumb line (H) fell. The drawing is from Astronomiae Instauratae Mechanica.

  However, Tycho had been using his new quadrant for less than a month when it proved its worth by bringing him to the attention of the academic elite, in the form of a well-known philosopher and iconoclast, Petrus Ramus. Ramus visited Augsburg in April 1570, and the two men—one a neophyte and the other a renowned scholar—were soon engaged in lively discussion about the future of astronomy. Ramus wanted to rid astronomy of all “hypotheses” and rebuild it totally from observation. The ideas that heavenly bodies must move in circles or epicycles with uniform motion and all other such assumptions would have to be discarded. Tycho agreed that such axioms of physics were not cast in stone, not immutable “truth.” He made the distinction, however, that the axioms of geometry were based on observation, not some flight of fancy. Furthermore, astronomy would not be possible without any hypotheses at all. He chose to side with the humanists and Philippists: There was recognizable order and harmony to the cosmos, and since there was, it would lend itself to hypothesizing.

  Tycho and Ramus were in complete agreement that the future of astronomy lay in numerous and exact observations. The celebrated Ramus, in his next book,12 described the quadrans maximus with admiration and mentioned a young Danish nobleman named Bracheus as its designer.

  Tycho had begun a second instrumental project, a large celestial globe made of wood, when a message arrived from his father. Otte Brahe was summoning all his sons back to Denmark, for his health was declining rapidly. Tycho was obliged to leave the globe in the hands of Hainzel and return home. By Christmas 1570 he had arrived at Helsingborg Castle, where his ailing father was still commander. The castle tower was a good vantage point for viewing the heavens, and entries in Tycho’s log show that he observed the Moon.

  Otte Brahe died the following May, 1571, survived by his wife Beate Bille, seven grown children, and one grandchild. Danish law stipulated that a lifetime widow’s jointure be set aside for Beate. The sons and daughters would share the remainder of the inheritance, with each son receiving twice a daughter’s share and sons given preference when it came to inheriting manors. Being the eldest son was not an advantage under the Danish inheritance laws: Tycho received no more than each of his brothers.

  Tycho and Steen, the next eldest son, jointly inherited the ancestral estate at Knutstorp, splitting the income from two hundred farms, twenty-five cottages, five and a half mills (one mill had been split in an earlier inheritance), and the manorial production and seigneurial rights of the estate. This was a small inheritance by the standards of Danish nobility: Tycho had come within a hairbreadth of inheriting a much larger fortune when his uncle died. Nevertheless, it was clear that when Otte’s will was settled, a procedure which normally took several years, Tycho would be financially independent.

  As eldest son, his first duty was to take his widowed mother back from the castle at Helsingborg to the family ancestral home at Knutstorp. In the months that followed, much of Tycho’s time was devoted to helping her and negotiating the settlement of the estate. Sometime during this period, Beate told Tycho about his twin. The revelation touched him profoundly, and he wrote a poem in Latin, phrased as though it came from the dead child who looked with pity on the one who was living: “He dwells on earth,”13 the brother in the poem says of Tycho, “while I dwell on Olympus.”

  fn1 The Alfonsine Tables, based on Ptolemy, were drawn up in 1252 by fifty astronomers under the patronage of Alfonso X of Castile. The Prutenic Tables, based on Copernicus, were drawn up in Wittenberg by a young colleague of Philipp Melanchthon, Erasmus Reinhold.

  fn2 Tycho’s first biographer,8 Pierre Gassendi, reported that skin grafts for nose replacement (performed by members of the potters’ guild) were done routinely and with a good success rate in Tycho’s day in India, where adultery was punishable by amputation of the nose.

  fn3 A pair of compasses, like a pair of scissors, is one instrument, not two.

  fn4 For the definition of altitude, horizon, and other vocabulary of astronomy, see chapter 7 and appendix 2.

  3

  BEHAVIOR UNBECOMING A NOBLEMAN

  1571–1573

  IN SPITE OF his steady drift toward the life of a scholar, during the period following his father’s death Tycho spent some of his time across the Øresund at the royal court in Copenhagen. He already had powerful family connections there, and now he fashioned closer ties with King Frederick II himself.

  The kings of Denmark and the Danish nobility related to one another in a complicated system of reciprocity.1 In accordance with an unspoken, unwritten, but nevertheless well understood and seriously regarded contractual arrangement, the scion of a noble family owed the king his loyalty and allegiance and a portion of his time and talents. The king’s obligation was to grant royal fiefs that provided substantial incomes. These grants were, in effect, the main glue that bound king and aristocracy together. Weighing in heavily on the side of the scales for a Brahe, Bille, and Oxe family member, in this arrangement, were his potential personal contributions to the welfare and prestige of the crown, the stature and power of the present extended family, and the valuable service rendered by previous generations of Brahes, Billes, and Oxes. Tycho’s uncle Jørgen Brahe had lost his life as a result of saving this very Frederick from drowning. Such acts were not forgotten when it came to the delicate question of who owed what to whom.

  Tycho, though his abilities and interests lay in different directions from most of his aristocratic contemporaries, was as highborn and courtly in his manners as any young nobleman of his generation. King Frederick was not without appreciation of the fact that although Tycho had wandered from the traditional path, he had, by doing so, developed some unique talents to offer the crown. Frederick was a king who valued scholarly pursuits. One of his avowed goals was to make Denmark famous for its learning, and he had generously endowed the University of Copenhagen to make it one of the finest educational centers in the world.

  The question now troubling the king and his advisors was whether Tycho, in addition to the promised canonry, should have a major fief. Was he equipped to manage one? Though he wore a sword and had fought a duel, and bore the scar from it, he was no warrior. He was not trained to ride into battle in armor or to command the defense of a castle, as his brothers were. Nevertheless, he clearly had to have something at least the equivalent of a fief. His powerful relatives at court were conferring with King Frederick and encouraging him to come up with an appropriate answer.

  By the end of the year his father died, Tycho was centering his life not at court in Copenhagen nor at Knutstorp but at Herrevad Abbey,2 where his uncle Steen Bille lived. Herrevad, a few miles from Knutstorp across rolling countryside, meadows, and woodlands, was situated where the more settled area nearer the Øresund ended, and its lands bordered on the deep, limitless forest of the north. It had been a Cistercian abbey, founded in 1144, a
nd a few aging monks were still there in Tycho’s day. The abbey church probably remained an austere Romanesque structure on the outside, but the interior had been completely altered in the thirteenth century in a lovely Gothic style. The Billes, Tycho’s mother’s family, had several holdings in the area, but Tycho’s uncle Steen had acquired Herrevad rather recently, in 1565. From its grand portal-house, suitably altered to be a noble dwelling, he administered the substantial estate that had once belonged to the Cistercians—hundreds of farms, mills, fisheries, and oak and beech forests where only the king was allowed to hunt the deer and stags. In addition to Steen Bille’s contingent of knights and their squires, his wife, Lady Kirstine, and her handmaidens and servants, and all the support staff that went into maintaining such an establishment, there was also a Lutheran Latin school for boys on the premises.fn1

  Steen Bille was a lively, outgoing man and extremely influential at the Danish court. He was also kind and gentle and associated happily with people of all social classes, especially relishing the company of scholars. With his encouragement and promise of active assistance, Tycho prepared to make good on his decision to take charge of his own career and research path. Uncle and nephew collaborated to transform Herrevad into a superbly equipped haven for the study of the subjects that interested Tycho and intrigued Steen as well. Setting up an independent research facility on this scale was unprecedented among Danish aristocrats, even among Danish scholars. Tycho and Steen Bille were treading new ground, and learning by trial and error.

  Not only was there to be an astronomical observatory, but they also planned a paper mill, an instrument factory, and an alchemy laboratory. Alchemy, though it would eventually come to have disreputable connotations as a strange obsession with turning base metal into gold, in Tycho’s day included medical alchemy and other related experimental science. It was the ancestor of modern chemistry. Tycho’s interest was primarily in medical alchemy. Herrevad already boasted a medical curiosity, a rib bone six feet long, said to have come from the burial site of a man named Vene. “Verily,” one scholar had commented, either seriously or wryly, “there did once3 live in these northern realms a people of wondrous dimension.”