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[169] KEPLER KEPLER [169]
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[169] KEPLER
KEPLER [169] This is true no matter to which point on the curve the two lines are drawn. Kepler found that the positions of Mars, as observed by Tycho, fitted into an elliptical orbit with a high degree of accuracy. It wasn’t a very flattened el lipse, but it was most definitely not a cir cle. Furthermore, the sun was located at one focus of the ellipse. Kepler found that the orbits of the other planets could also be drawn as el lipses with the sun always at one of the foci. He announced this in Astronomia Nova, a book published in 1609, and this is now known as Kepler’s first law. The book also contained his second law: “A line connecting the planet and the sun will sweep over equal areas in equal times as the planet moves about its orbit.” This meant that the closer a planet was to the sun the faster it would move according to a fixed and calculable rule.
Kepler went on later to apply these laws to the satellites of Jupiter as well. However, he was unable to handle earth’s own moon. Its motions were too complicated. This was done in 1638 by Horrocks [200]. Kepler’s ellipses put an end to Greek astronomy. They destroyed the sa credness of circular motion and abol ished the celestial spheres that Eu doxus [27] had placed in the heavens two thousand years before, and which even Copernicus had retained. Kepler’s scheme of the solar system has been fol lowed by astronomers ever since, without significant modification. (Kepler’s insight was restricted to the solar system. The stars, he thought, all occupied a thin shell some two miles thick far outside the solar system. Here he was far behind Bruno [157].) With the abolition of the celestial spheres some other cause had to be found to explain the fact that the heav enly bodies remained in their orbits. The fact that the sun was always at one focus of the elliptical orbit, that it was always in the plane of the orbit, that planetary motion was faster the closer the planet was to the sun, made it obvious to Kepler that the sun somehow controlled the motions of the planets. He followed the notions of Gilbert [155] in thinking that some magnetic force was involved, but the systems he attempted to work out on such a basis were unsatisfactory. It was left for Newton [231] to suggest a satisfactory explanation a half century later. Kepler published another book in 1619, one that was particularly full of verbose mysticism. Kepler, aware of its difficulty, despondently suspected it might have to wait a century for a reader. In it, however (rather like a pearl in a mass of seaweed), was what is now called Kepler’s third law, which stated that the square of the period of revolution of a planet is proportional to the cube of its distance from the sun. Again the sun seemed indicated as the controller of planetary motion. The book was dedicated to James I of Great Britain, a royal pedant to whom a turgid book was meat and drink and a dedication the dessert to top it with. James invited Kepler to England, but the astronomer refused to leave Germany even though that land was now plunging into the Thirty Years’ War. Kepler and Galileo [166] carried on a friendly correspondence for a time, though they never met, and Kepler com municated his theories to Galileo. Gali leo, however, in his book on the Co- pemican theory made no mention of Kepler’s laws. Presumably he felt they were as little to be regarded as Kepler’s fantasies about regular solids and the music of the spheres (to say nothing about his horoscopes—although Galileo, on occasion, could cast one too). As a matter of fact, the correspondence had been broken off in 1610, and this may indicate the loss of sympathy between the two.
Nevertheless, when Galileo was con structing telescopes and sending them where he thought they would do the most good, one found its way to Kepler. Kepler used the telescope to observe Jupiter’s moons—which he had refused to accept till he saw them with his own eyes—and promptly described them as “satellites,” from a Latin term for the hangers-on of a powerful man. He began to work on the manner in which light
[ 1 6 9 ] KEPLER
BAYER [170] waves were refracted by lenses. He man aged to explain in this way how it was that telescopes (and eyes, too) per formed their function. He described an improved telescope in 1611, using two convex lenses in place of the one convex and one concave used by Galileo, and described, in theory, a compound microscope better than any then available. He also showed that a parabolic mirror focused parallel rays of light, a fact essential to the development of reflecting telescopes by Newton later in the century. Thus he founded the sci ence of modem optics. But he was not able to deduce a general mathematical relationship to express the refraction of light. That was left for his younger con temporary Snell [177], In 1612 Kepler’s protector, Rudolf II, died. (So did Kepler’s wife, and a sec ond marriage, to a younger woman, brought him happiness.) The new em peror, Matthias, maintained Kepler in his position as court astronomer with a salary that was usually in arrears. (Ru dolf n had not been a prompt payer ei ther. The Holy Roman emperors were usually strapped for cash.) In 1618 Kepler’s mother, who dabbled in the oc cult, was arrested as a witch and, al though not tortured, did not long survive her release, which was procured through her son’s long-sustained efforts. Kepler spent these years completing new tables of planetary motions based on Tycho’s superlative observations and his own theory of elliptical orbits. He used the newly invented logarithms of Napier [159] in his calculations, this being the first important use to which logarithms were put. Despite family troubles, financial difficulties exacerbated by the fact that Kepler fathered thirteen children, and continuing war and reli gious unrest, the tables, called the Rudol phine Tables in honor of Kepler’s old patron, were published in 1627 and dedi cated to the memory of Tycho. The work included tables of logarithms and Tycho’s star map as expanded by Kepler. Kepler’s final service to astronomy was his calculation of the times of passage of the inner planets Mercury and Venus across the face of the sun. Such passages 108 had never been observed, but according to Kepler’s calculations they had to take place. In 1631 such a “transit” of Mer cury was observed by Gassendi [182] at the predicted time, but Kepler by then was dead of a fever, followed by enthusi astic medical bleeding. Kepler, by the way, wrote a story, “Somnium,” about a man who traveled to the moon in a dream. For the first time the lunar surface was described as it really was, so that “Somnium” may be considered the first piece of authentic science fiction, as opposed to fantasy. It was published after Kepler’s death. Kepler’s manuscripts were eventually bought by Catherine II of Russia over a century after his death and are preserved now at the Pulkovo Observatory in the USSR. [170] BAYER, Johann (by'er) German astronomer Born: Rain, Bavaria, 1572 Died: Augsburg, Bavaria, March 7, 1625
While Kepler [169] was putting the planetary system into its modem shape, his countryman Bayer, a lawyer by pro fession and adviser to the Augsburg City Council, was adding a modem touch to the stars themselves. The constellations and their names stretch back to antiquity and have al ways proved a useful means of dividing the starry vault. The names of the stars within the constellations were in ancient times not so well organized. The bright ones were given names of course and the present versions of those names are mostly derived from the Arabic. Betel geuse, Aldebaran, and Rigel bear witness to the centuries between the eighth and the eleventh when it was the Arabs who preserved Greek astronomy. Some names, such as Castor, Pollux, and Sirius, date back to classical times. How ever, there was no way of associating the name of a star with the constellation that contains it except brute memory. In 1603 and 1627 Bayer published edi tions of Uranometria, a catalogue of the heavens (the first one to show the entire
6. P to lem y PITAGORAS 1. P
ythagoras 2. H
ippocrates 4. E
uclid 3. A
ristotle 5. A r c h im ed es 7. N icolas
C opernicus 9. G alen
8. R oger
B acon
10. A ndreas
V esalius
11. G alileo G alilei a n d th e D uke of P adua 12. J o h ann K epl er 13. W illiam
H arvey
14. R ené
D escartes
15. R obert
B oyle
16. A nton
van
L eeuwenhoek 17. I saac N ew to n 18. B e n ja m in F r ank lin 19. H enry
C avendish
20. S ir W illiam H erschel 21. A n t o in e L. L avoisier 22. E dw ard J e n n e r [171] MARIUS
OUGHTRED [172] celestial sphere) that corrected this. He described the constellations carefully and located more stars (1,706 altogether) than Tycho Brahe [156] had done in his catalogue. In addition, and more important, Bayer listed the stars of each constel lation by Greek letters in order of brightness. Thus Betelgeuse, the brightest star in Orion, became Alpha Orionis, while Rigel was Beta Orionis, and Bella trix was Gamma Orionis. This device has been kept to the present. Indeed, some bright stars of the southern skies, which have been observed carefully only since Bayer’s day, are known only by this sys tem. Thus the brightest star of the south ern heavens and—as Henderson [505] was to show two centuries later—the star that is closest to us is in the constellation Centaurus and is known only as Alpha Centauri. (In later years, as more and fainter stars were studied, Roman letters and numbers, alone and in combination, had to be brought into use.) Bayer, who was an amateur theologian and an ardent Protestant, did not suc ceed in another project. Offended by the heathen names of the constellations, he tried to introduce a system whereby the northern constellations were given names from the New Testament, and southern constellations from the Old. [171] MARIUS, Simon German astronomer Born: Gunzenhausen, January 20, 1573
Died: Anspach, Bavaria, December 26, 1624 Marius’ real name was Mayer but, like many another scholar of the time, he used a Latinized version in his scholarly career. He studied astronomy under Tycho Brahe [156] and medicine in Italy and served as court astronomer for the elector of Brandenburg. His career is possibly an unsavory one. He seems to have had one of Galileo’s [166] works copied and published under another author’s name, and he claimed (apparently without justification) to have seen the four satellites of Jupiter in 1609 before Galileo had. We can well imagine that Galileo was furious at this and charged into the fight with all his strength. Yet one aspect of Marius’ work, even if false, remains. Galileo had not named Jupiter’s satellites, but Marius did. Marius made use of Greek mythology and chose the names Io, Europa, Gany mede, and Callisto—four individuals who were closely involved with Jupiter (Zeus) in the myths. Those names re main. Marius also prepared tables of their motions before Galileo did. Marius made one discovery that, ap parently, no one disputes as Marius’. In 1612 he was the first astronomer to men tion the Andromeda Nebula, the most distant object one can see without a telescope—though that fact was not to be appreciated for three more centuries. [172] OUGHTRED, William (aw'tred) English mathematician Born: Eton, Buckinghamshire, March 5, 1574 Died: Albury, Surrey, June 30, 1660
Oughtred, who obtained his master’s degree at Cambridge in 1600, was a minister and not a professional mathe matician, but that makes little difference since he spent almost all the time he could spare on mathematics, even when it meant sleeping but two or three hours a night.
He published a textbook on mathe matics in 1631 in which he introduced the multiplication sign ( X ) and the ab breviations commonly used today for the trigonometric functions: sin, cos, and tan for sine, cosine, and tangent. His greatest innovation, however, came in 1622, and consisted of two rulers along which logarithmic scales were laid off. By manipulating the rulers and sliding one against the other, calcu lations could be performed mechanically by means of logarithms. We know it now as a slide rule, and, for centuries, engi neers carried slide rules at least as lov ingly as any physician ever carried his stethoscope and tongue depressor.
[173] SCHEINER
HARVEY [174] He was a pronounced royalist but managed to keep his post during the time of Cromwell and the Common wealth. There is a story that he died of joy at hearing that Charles II had been recalled and the British monarchy was to be re-established. However, he was eighty-five at the time and undoubtedly the thread of life was sufficiently frayed to require no great drama to bring about death.
[173] SCHEINER, Christoph (shigh'- ner)
German astronomer Born: Wald, Rhine Province, July 25, 1575 Died: Neisse, Silesia (now Nysa, Poland), June 18, 1650 Scheiner taught Hebrew and mathe matics, first at Freiburg and then at In golstadt (where he had studied). He was appointed professor of Hebrew and mathematics at Ingolstadt in 1600. He observed sunspots on a projection of the sun’s disc in March 1611. This was not really very unusual, for some spots are big enough to be seen by the unaided eye and records of their occasional observa tion dated back to ancient times. Scheiner claimed to have seen them be fore Galileo [166], however, and that ir ritated the contentious Italian who plunged eagerly into controversy. When Scheiner (a Jesuit since 1595) first reported his discovery to his supe rior, the latter warned him to be careful in his interpretations, for Aristotle [29] had said nothing about spots on the sun. Scheiner therefore judged them to be small bodies, circling the sun but not part of it. (It did not occur to him, ap parently, that Aristotle had said nothing about that either.) This was all Galileo needed. He at tacked both Scheiner and Aristotle in his best polemical style, and this helped end the brief popularity of Galileo with the church authorities and began the long road that ended in the inquisitorial chambers. Scheiner also studied the physiology of vision and showed that the curvature of the lens changes as the eye focuses to different distances. This is called “ac commodation.” [174] HARVEY, William English physician
1578
Died: London, June 3, 1657 As a young man, Harvey (the son of a well-to-do businessman and the oldest of nine children) supplemented his educa tion at Cambridge (from which he took his degree in 1597) by courses at the medical school in Padua, Italy, which ever since Mondino’s [110] day, three centuries before, had been the world’s greatest. There he studied under Fabri- cius ab Aquapendente [151] among others.
Harvey was in Italy when Galileo [166] was making his mark and it was Harvey’s great feat to apply the Galilean view of science to physiology and medi cine. One of Galileo’s Italian colleagues, Sanctorius [165], made a start in this di rection, but Harvey was to outstrip him. After obtaining his medical degree in 1602 Harvey returned to England, where he married and set up a most successful practice. Francis Bacon [163] was one of his patients, and from 1618 he was court physician for James I and Charles I until the latter was beheaded in 1649. He was more interested in medical research than in routine practice. By 1616, he is supposed to have dissected eighty species of animals. In particular he studied the heart and blood vessels. Men such as Servetus [142] had groped toward the concept of the circulation of the blood. Harvey, however, was not a speculator but an experimenter. He de termined the heart was a muscle and that it acted by contracting, pushing blood out. Through actual dissection he noted that the valves separating the two upper chambers of the heart (auricles) from the two lower (ventricles) were one-way. Blood could go from auricle to ventricle but not vice versa. There were one-way valves in the veins too, these having been discovered by Fabricius. For
[174] HARVEY
HARVEY [174] that reason, blood in the veins could travel only toward the heart and not away from it. In fact, it was the valves in the veins that first put Harvey on the right track, as, late in life, he explained to the young Boyle [212]. When Harvey tied off an artery it was the side toward the heart that bulged with blood. When he tied off a vein the side away from the heart bulged. Every thing combined to indicate that blood did not oscillate back and forth in the vessels as Galen [65] had believed but traveled in one direction only. Furthermore Harvey calculated that in one hour the heart pumped out a quan tity of blood that was three times the weight of a man. It seemed incon ceivable that blood could be formed and broken down again at such a rate. Therefore it had to be the same blood moving in circles, from the heart to the arteries, from these to the veins, from those back to the heart. The blood, in other words, moved in a closed curve. It circulated. He began lecturing on the subject in 1616, but it was not until 1628 that he published these conclusions and the evi dence backing them in a small book of only seventy-two pages, miserably printed in Holland on thin, cheap paper and full of typographical errors. How ever, the experiments it described were clear, concise, and elegant, and the con clusions were incontrovertible. The book became one of the great scientific clas sics. Its short title is Exercitatio De
tions of the Heart and Blood’’). Harvey was ridiculed at first, for it was no light matter to refute Galen. His practice fell off and learned doctors wrote tomes refuting him (by quoting Galen and not by repeating Harvey’s ex periments). Harvey was called Circula tor, which was a cruel pun, for it was the Latin slang for “quack,” the name given to peddlers who hawked medicines at the circus. He did not take much part in the controversy, but let the facts speak. For that matter, Harvey avoided controversy on principle and did not en gage in the polemics that delighted the anatomists of the day. Harvey had led the team of doctors at the bedside of James I on the occasion of his last illness in 1625. James’s son, who succeeded as Charles I, had enough faith in Harvey to let him have royal deer with which to experiment, and at the king’s command, Harvey performed a postmortem on the body of Thomas Parr (“Old Parr”) who died in 1635 at a reputed, but almost certainly exagger ated, age of 152. Harvey was one of the first to study the development of the chick in the egg, something that had once interested Aris totle [29]. Although in attendance on Charles I during the English Civil War, in which Charles lost throne and head, Harvey did not fall victim to partisan passion, but returned safely to London, though revolutionaries did break into his home and destroy some notes and speci mens. (In particular, Harvey is supposed to have been at the battle of Edgehill in 1642 and spent his time there calmly reading a book while waiting for any royal call.) By the time of Harvey’s old age the fact of circulation was accepted by phy sicians generally. Even in France, where opposition was strongest, the influential Descartes [183] supported Harvey. Har vey was elected president of the College of Physicians in 1654. He declined the privilege, preferring to spend his last years in peace. The validity of the theory of circula tion depended on the blood’s passing from the arteries to the veins, but there were no visible connections between those blood vessels. Harvey, noting that both arteries and veins divided and sub divided into finer and finer vessels till they passed out of sight, supposed the connections were simply too fine to see. This was proved correct by Malpighi [214], who had the advantage of the use of a microscope. This final proof was not obtained until four years after Harvey’s death.
Since Harvey’s small book was the end of Galen and of Greek medicine, the En glish physician may be considered the founder of modem physiology. His personal library, which he left to
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