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136 [214] MALPIGHI
MALPIGHI [214] tion of all living species of both plants and animals. He was to do it in company with a younger man who was to finance the effort. The friend died soon after but left money in his will for the purpose. In 1667 Ray published a catalogue of plants in the British Isles and was elected a member of the Royal Society. He re fused to serve as secretary, however, as that would take time from his work. To ward the end of his life he had general ized his catalogue into a three-volume encyclopedia of plant life, published be tween 1686 and 1704. He described 18,600 differeht plant species and laid the groundwork for systematic classifica tion, which was to be brought into mod ern form by Linneaus [276]. Ray also tried to systematize the ani mal kingdom and in 1693 he published a book that contained the first logical classification of animals, based chiefly on hoofs, toes, and teeth. His descriptions finally destroyed the fanciful stories of animals inherited from Pliny [61], six teen centuries earlier. His views on fossils were rather enlightened for the time. In 1691 he published an account in which he de clared fossils were the petrified remains of extinct creatures. This was not ac cepted by biologists generally until a cen tury later. [214] MALPIGHI, Marcello (mahl-pee'- gee)
Italian physiologist Born: Crevalcore, near Bologna, March 10, 1628 Died: Rome, November 30, 1694 When Galileo [166] invented the tele scope he well realized that an arrange ment of lenses could also be used to magnify objects. In a sense he was inven tor of the microscope as well. The opti cal theory of the microscope was further advanced by his friend Kepler [169] and by his young assistant Torricelli [192]. In the mid-seventeenth century microscopy became all the rage and a number of first-rate investigators took it up. First by a hair and therefore entitled to be called the father of microscopy was Malpighi. He was a physician by training, obtaining his medical degree at the University of Bologna in 1653 after an interruption caused by the death of his father. He then lectured at various Italian universities, though chiefly at Bo logna, and associated with Redi [211] and Borelli [191] among others. In 1691 he finally retired to Rome, rather reluc tantly, to become private physician to Pope Innocent XII. Malpighi began his work in micros copy in the 1650s by investigating the lungs of frogs. In 1660 he showed that the blood flowed through a complex net work of vessels over the lungs and this discovery led to important conclusions. In the first place it explained a key step in the process of respiration, for it was easy to see that air could easily diffuse from the lungs into the blood vessels and that the blood stream would then carry it to all parts of the body. Soon Swammer dam [224] was to detect the structures within the blood stream that were even tually found to carry the essential por tions of the air and Lower [219] was to arrive at the first suspicions of the true details of the process. Malpighi’s observations of the wing membranes of a bat showed him the finest blood vessels, which were eventu ally named capillaries (“hairlike”). In visible to the eye, these were clearly visi ble in the microscope. They connected the smallest visible arteries with the smallest visible veins. With this discovery Malpighi supplied the key factor lacking in the theory of blood circulation ad vanced a generation earlier by Harvey [174], who died a few years too soon to witness this triumph. At about this time, too, Rudbeck [218] added his final touch to the circulatory system. He disproved the impression that there were two varieties of bile, yellow and black, thus disposing of a mistaken belief that dated back to the school of Hip pocrates [22] two thousand years before. Malpighi went on to study other mi nute aspects of life—chick embryos and insects, for instance. He devoted a vol ume to the internal organs of the silk worm, the first treatise to deal with an invertebrate. Without quite realizing
[215] HUYGENS
HUYGENS [215] what he had discovered he found traces of gill structures in the developing chick, attesting to its descent from fishlike crea tures. (One of Malpighi’s contempo raries, Graaf [228], unwittingly went even further back than the embryo in his investigations.) Malpighi studied the respiratory ves sels in insects—tiny, branching tubes that filled the body and opened to the outer world through tiny apertures in the abdomen. In the stems of plant structures he found tiny tubes that pos sessed a spiral structure. Because of their resemblance to the tubes in insects, he wrongly believed them to be used in respiration. He described the small open ings (stomata) on the underside of leaves. These, whose function he could not guess, were concerned with respira tion. This interest in plant microscopy was shared by his younger contemporary Grew [229], Malpighi’s researches were so famous that in 1667 the Royal Society in Lon don suggested he send them his scientific communications. The work of Malpighi and his fellow microscopists showed that living tissue was far more complex in structure than the eye alone could tell and that the world of the very small was as grand and worthy of study as the world of astron omy. [215] HUYGENS, Christiaan (hoy'genz or h/genz) Dutch physicist and astronomer Born: The Hague, April 14, 1629 Died: The Hague, June 8, 1695 Huygens’ father was an important official in the Dutch government. Young Christiaan was given a good education at the University of Leiden and had the benefit of friendship with Descartes [183]. Huygens’ early training was in mathematics and he might have made a great mark in that field had he not been diverted to astronomy and physics. In 1657, for instance, he published a book on probability, the first formal book on the subject to appear, and applied the subject to the working out of life ex pectancy. In 1655, when he was helping his brother devise an improved telescope, he hit upon a new and better method for grinding lenses. (He had the help here of the Dutch-Jewish philosopher Benedict Spinoza.) At once he incorporated these improved lenses into telescopes and began to use one, twenty-three feet long, to discover new glories in the heavens, such as (in 1656) a huge cloud of gas and dust, the Orion Nebula. Another dis covery, that same year, was a satellite circling Saturn, one as large as any of the satellites of Jupiter that Galileo [166] had discovered nearly half a century be fore. Huygens named it Titan. At that moment six planets (including the earth) and six satellites (including the moon) were known and this seemed such a neat picture that Huygens declared no more of either remained to be discovered. He lived to see Cassini [209] discover four more satellites of Saturn. Huygens’ mysticism was a momentary aberration and his real achievements continued. Galileo had, in 1610, noted a peculiarity about Saturn: it seemed tri ple. His primitive telescope could not make out the nature of the tripleness, but Huygens’ improved instrument made it out clearly. In 1656 he was able to see that Saturn was surrounded by a thin ring which nowhere touched the planet. He announced his discovery in a cipher, protecting his priority while making cer tain he was correct through further ob servations. Cassini was to improve on Huygens, for he discovered the ring was a double one. Huygens recognized that the plane of the ring was tipped to that of earth’s orbit and that they would be seen edge-on, and therefore be briefly invisible, every fourteen years. Huygens was the first to note surface markings on Mars. In 1659 he detected the V-shaped Syrtis Major (“large bog”), whose name proved to be a mistake, for there is nothing boggy about it. He was the first to make a specific guess at the distance of the stars. By as suming Sirius to be as bright as the sun, he estimated its distance at 2.5 trillion miles. (This is about one-twentieth the 138 [215] HUYGENS
HUYGENS [215] actual distance and Huygens’ error lay in his assumption, for Sirius is actually much brighter than the sun and must be correspondingly farther to appear as dim as it does.) Huygens believed, as Nicho las of Cusa [115] had, that stars were uniformly distributed through infinite space, each with its complement of planets.
Huygens struggled to reduce telescopic observations to a quantitative basis. This he did in two ways: in the measurement of space and the measurement of time. For the former, Huygens devised a mi crometer in 1658 with which he could measure angular separations of a few seconds of arc. In this form of quanti tative observation his work rather paral leled that of his contemporary Picard [204]. In the measurement of time, how ever, was to be found his greatest achievement. The best device the an cients had with which to measure time was the water clock of Ctesibius [46], but this was only accurate to rather large fractions of an hour. The late Middle Ages developed mechanical clocks in which the pointer was made to indicate the hour through the action of a slowly falling weight rather than slowly rising water. The elimination of water made the clocks more rugged, less in need of care, and therefore more suitable for in stallation in church towers, but they were insufficiently accurate for scien tific use. What was really needed was some de vice that kept a constant periodic motion to which a clock could be geared, but no such motion was known until Galileo discovered the isochronicity of the pen dulum. Galileo did not fail to recognize the possibility of hitching a pendulum to the gears of a clock and in his old age even had a design for such a clock drawn up. It was Huygens who put the possibility into practice in 1656, over a decade after Galileo’s death. He showed that a pendulum didn’t swing in exactly equal times unless it swung through an arc that wasn’t quite circular. He devised attach ments at the pendulum’s fulcrum that made it swing in the proper arc and then attached that to the works of a clock, using falling weights to transfer just enough energy to the pendulum to keep it from coming to a halt through friction and air resistance. It was with Huygens’ first “grandfa ther’s clock,” which he presented to the Dutch governing body, the estates gen eral, that the era of accurate timekeeping may be said to have begun. It is difficult to see how physics could have advanced much further without such an invention. Huygens extended Wallis’ [198] findings on the conservation of momen tum (mass times velocity, or mv). Huy gens showed that mv2 was also con served. This quantity is twice the kinetic energy of a body and this was the first step in the direction of working out the law of conservation of energy, which was to be brought to the attention of sci ence by Helmholtz [631] a century and a half later. Huygens’ reputation spread throughout Europe. In 1660 he visited England and in 1663 was elected a charter member of the Royal Society. Louis XIV lured him to France in 1666 in line with his policy of collecting scholars for the glory of his regime. There, Huygens helped found the French Academy of Sciences. Huygens, like Cassini might have re mained in Paris for the rest of his life, but he was Protestant. Louis was gradu ally moving in the direction of non toleration for the Protestants, and in 1681 Huygens returned to the Nether lands.
As he corrected Galileo on the ques tion of Saturn, so he endeavored, in 1690, to correct Newton [231] on the subject of light. To Huygens it seemed quite possible that light could be inter preted as a longitudinal wave, a wave that undulated in the direction of its mo tion, as a sound wave did. The chief objection to such a wave theory was that most people, through their experience with water waves and sound waves, believed that waves would bend around obstacles. Only a stream of particles, they thought, would travel in absolutely straight lines and throw sharp shadows, as light rays did. Huygens tried to show that there were
[216] BRAND
RUDBECK [218] conditions under which waves would in deed travel a straight line and would fol low the laws of reflection and refraction which were observed in the case of light. In addition Grimaldi [199] showed that light had a slight tendency to bend about obstacles after all. However, Newton’s theory that light consisted of particles remained the more popular throughout the eighteenth cen tury, mainly because of Newton’s im mense prestige. The wave theory re mained disregarded for a full century until the time of Young [402].
German chemist Born: Hamburg, about 1630 Died: date and place unknown Brand was a military officer who called himself a physician though he had never earned a degree. He is sometimes called the last of the alchemists (which he wasn’t really), though he might better be called the first of the element discov erers.
He was the first man known to have discovered an element that was not known in any form before his time. The date of the discovery is disputed, but it must have been somewhere between 1669 and 1675. Brand was searching for the philosopher’s stone and it occurred to him that he could find it in urine. He did not succeed, but he obtained a white, waxy substance that glowed in the dark. He therefore called it phosphorus (“light-bearer”). The glow was the result of the slow combination of the phos phorus with air, but that was not to be understood for another century. The glow, however, served the purpose of making the discovery mysterious and glamorous. Several men quarreled over who had first made this brilliant find, but the quarrels were less important than the fact that another step had been taken away from the mysticism of alchemy to ward the rationality of chemistry. What happened to Brand after his dis covery is utterly unknown. [217] RICHER, Jean (ree-shay') French astronomer Born: 1630 Died: Paris, 1696 Richer was elected to the French Academy of Sciences in 1666 and in 1671 led an expedition to Cayenne in French Guiana (quite near the equator). There he made careful observations of Mars while Cassini [209], his superior, did the same in Paris. Together, these measurements supplied the first adequate parallax of Mars and the first notion of the scale of the solar system. Richer also found that a pendulum beat more slowly in Cayenne than in Paris, so that a clock, correct in Paris, lost two and a half minutes a day in Cayenne. The conclusion was that the force of gravity was weaker in Cayenne because the spot was farther from the center of the earth. (The rate of beat of a pendulum varies with the size of the force of gravity acting upon it.) If Cayenne had been on a mountain top that would not have been surprising, but it was at sea level. Consequently Newton [231] deduced that the surface of the sea itself was farther from the center of the earth in the equatorial re gions than in more northerly regions. This would be true if the earth was an oblate spheroid as the theory of gravita tion required. (Actually it is now known that the equatorial surface is thirteen miles farther from the center of the earth than the polar surfaces.) Richer returned to Paris in 1673 to such acclaim as to rouse the jealousy of Cassini. Since Richer was a military en gineer as well as an astronomer, Cassini arranged to have him bundled off to the provinces to erect fortifications. The rest of his life was spent in obscurity. [218] RUDBECK, Olof (rood'bek) Swedish naturalist
1630
Died: Uppsala, September 17, 1702
140 [219] LOWER
WREN [220] Rudbeck, the son of a science-minded bishop and the tenth of eleven children, was a man of encyclopedic interests. He taught at the medical school at the Uni versity of Uppsala, Sweden, and there took anatomy, botany, chemistry, and mathematics as his subjects. He built up a beautiful botanical garden. He was a well-read classical scholar and was made chancellor of the university at the age of thirty-one. In science his best-known discovery is the lymphatic vessels, which he demon strated to Queen Christina of Sweden in 1653, using a dog for the purpose. The lymphatics resemble the veins and capil laries but have thinner walls and carry the clear, watery fluid portion of the blood (lymph). This fluid portion is forced out of the thin-walled capillaries and into the spaces around the cells, forming the interstitial fluid. The intersti tial fluid is connected in the lymphatics and carried back into the blood vessels. In various regions of the body, lym phatic vessels gather in small knots (lymph glands or lymph nodes), which are now known to be important in de veloping immunity to disease. These were first noted by Malpighi [214] in 1659. Rudbeck quarreled with Bartholin [210] over priority in this discovery. Outside the world of science Rudbeck is known for a curious quirk. He thor oughly believed the fictional tale of Plato [24] concerning the supposedly-lost con tinent Atlantis and wrote a large treatise, in several volumes, attempting to prove that Atlantis was really Scandinavia and that Sweden particularly was the fount of human civilization. [219] LOWER, Richard English physician Born: near Bodmin, Cornwall, about 1631 Died: London, January 17, 1691 Lower obtained his bachelor’s degree from Oxford in 1653 and his medical de gree there in 1665. He was elected to the Royal Society in 1667 after being nomi nated by Boyle [212]. He made two dis coveries involving blood that had to await future centuries for proper under standing. He discovered that dark venous blood was converted to bright arterial blood on contact with air. Something, he believed, was absorbed from air, but what that might be had to wait a century for Lavoisier’s [334] explanation of the nature of air. In 1665 he transfused blood from one animal to another, at the suggestion of Christopher Wren [220], and demon strated that this technique might be use ful in saving lives. However, the transfu sion of animal blood into a man or even one man’s blood into another was too often fatal. Landsteiner [973], two and a half centuries later, demonstrated the existence of different types of human blood, and it was only in the twentieth century that transfusion became practi cal.
Lower disproved Galen’s [65] notion that phlegm originated in the brain by showing that it was manufactured in the nasal membranes. He also showed that the heartbeat was caused by the contrac tion of the heart’s muscular walls. [220] WREN, Sir Christopher English architect Born: East Rnoyle, Wiltshire, October 20, 1632 Died: London, February 25, 1723 Wren was the son of a clergyman (and royal chaplain). He obtained his master’s degree at Oxford in 1654, and in 1657 became professor of astronomy at Gresham College. Although he and his family were royalists, he was left un disturbed by Cromwell. He is best known as an architect, hav ing designed the new St. Paul’s Cathe dral, constructed in London after the disastrous fire of 1666. He designed other churches as well and was knighted for his services in 1673. He would have deserved even more from his nation had he been allowed to carry through his orderly design for a new, rationally planned London. The interests of those who owned London land prevented it.
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