Biographical encyclopedia
Download 17.33 Mb. Pdf ko'rish
|
- Bu sahifa navigatsiya:
- BERTHOLLET
231 [342] HJELM
BODE [344] ble, though “asteroids” may always re main more popular. Over sixteen hundred planetoids are now known, so that Piazzi’s discovery was not that of a planet merely, but of a whole zone of planets. At the time of Piazzi’s death, however, the number of known planetoids was still only four. When the thousandth planetoid was dis covered in 1923, it was named Piazzia in his honor. [342] HJELM, Peter Jacob (yelm) Swedish mineralogist Born: Sunnerbo Harad, October 2, 1746
Died: Stockholm, October 7, 1813 Hjelm was a friend of Scheele’s [329] who gets credit for discovering a metal on which Scheele worked. In 1781 at the suggestion of Scheele, Hjelm used methods similar to Gahn’s [339] in iso lating manganese. The result was the iso lation of still another metal, and new ele ment, molybdenum. [343] CHARLES, Jacques Alexandre César (shahrl) French physicist Born: Beaugency, Loiret, Novem ber 12, 1746 Died: Paris, April 7, 1823 Teaching at the Sorbonne, Charles, who held a minor government post and was granted a small pension by Louis XVI, popularized Franklin’s [272] one- fluid theory of electricity. He proved a skillful and popular lecturer on science for the layman. Upon hearing of the experiments of the Montgolfier brothers [325] on bal loons, he realized at once that hydrogen, the lightness of which had been discov ered fifteen years earlier by Cavendish [259], would be a far more efficient buoyant force (though much more ex pensive) than hot air. On August 27, 1783, he constructed the first hydrogen balloon, inventing, in the process, all the devices used to handle and manipulate balloons. He himself went up several times, reaching a height of over a mile, and helped establish an aeronautic craze, ex emplified by such men as Blanchard [362], Louis XVI, who was fascinated by balloons, continued to patronize Charles, which made him unpopular to the revo lutionaries. During the French Revolu tion he might have been killed by a mob, had he not won them over by reciting his ballooning achievements. His most important discovery was re ally a rediscovery. He repeated the work of Amontons [244] about 1787 and showed that different gases all expanded by the same amount with a given rise in temperature. Charles’s advance lay in his being the first to make an accurate esti mate of the degree of expansion. For each degree (Centigrade) rise in temper ature, he found, the volume of a gas ex panded by
of its volume at 0°. For each degree of fall, the volume con tracted by % 7 3 of that volume. This meant that a temperature of —273°C the volume of a gas would reach zero (if the law held good) and that there could be no lower tempera ture. It was two generations later that Kelvin [652] was to crystallize this no tion of an absolute zero. Charles did not publish his experi ments, and about 1802 Gay-Lussac [420], also a balloon-ascensionist, pub lished his own observations in this mat ter, duplicating those of Charles. The rule that the volume of a given quantity of gas is proportional to the absolute temperature where pressure is held con stant is sometimes called Gay-Lussac’s law and sometimes Charles’s law. [344] BODE, Johann Elert (boh'duh) German astronomer
Bode, the son of a teacher, was self educated in astronomy and was writing astronomy texts in 1766, while he was still a teenager. In 1777 he took a posi
[345] JUSSIEU
BERTHOLLET [346] tion as assistant to Lambert [299] and advanced rapidly. He became director of the Berlin Observatory in 1786, and was the author of a vast catalogue of star po sitions, issued in 1801. Nevertheless he is best known for pop ularizing a relationship that he did not originate. It had been pointed out in 1772 by Titius [301] that one might start with the series 0, 3, 6, 12, 24, 48, 96, 192, . . . each number (after the first two) double the one before. If one added 4 to each, then the series became 4, 7, 10, 16, 28, 52, 100, 196. . . . If one sets the earth’s distance from the sun at 10, then Mercury is, in proportion, at dis tance 4 and Venus at distance 7 (at least roughly). Similarly Mars is at 16, Jupiter at 52, and Saturn at 100 (roughly). This relationship is still known as Bode’s law, though lately quite often as the Bode-Ti tian law. At the time it was popularized, no planet was known for position 28, though even Kepler [169], nearly two centuries before, had felt the gap be tween Mars and Jupiter to be too large, and had suggested that a small planet might exist there. When Uranus was discovered and found to be at position 196 (roughly), astronomers could no longer resist. The search began for the planet at position 28, which Ceres filled nicely. However, when Leverrier [564] discovered Nep tune, it was found in a position quite far from that predicted by Bode’s law, al though Leverrier had made use of it in his calculations, and the law’s impor tance vanished. [345] JUSSIEU, Antoine Laurent de (zhyoo-syuh') French botanist Born: Lyon, April 12, 1748 Died: Paris, September 17, 1836 Jussieu was a member of a distin guished family of botanists. An uncle, Bernard, had first identified sea anem ones and related creatures as animals rather than as plants, which they resem ble. Another uncle, Joseph, had been a member of the Peruvian expedition of La Condamine [270]. Antoine Laurent himself began his work in 1765 under his uncle Bernard and obtained his doctorate in 1780. He popularized a system of natural classification of plants in 1789 that was the base upon which Cuvier [396] and Candolle [418] built, a generation later. Jussieu was placed in charge of the hospital of Paris during the French Rev olution and in 1793 was appointed pro fessor of botany at the Jardin des Plantes, a post he held till his retirement in 1826.
[346] BERTHOLLET, Claude Louis, Comte (ber-toh-lay') French chemist
December 9, 1748 Died: Arcueil, near Paris, No vember 6, 1822 Berthollet was bom of poor French parents in what was then part of Italy. He obtained his medical degree at the University of Turin in 1768 and moved to Paris in 1772. He was one of the first to accept Lavoisier’s [334] new theories, and he joined with him in devising the new chemical nomenclature. On his own, Berthollet continued Scheele’s [329] research on chlorine, showing in 1785 how it could be used for bleaching, but like Scheele he was convinced that it was a compound and contained oxygen. He continued Priest ley’s [312] investigation of ammonia and was the first to show its composition (of nitrogen and hydrogen) with reason able precision. He discovered potassium chlorate and Lavoisier thought its explo sive qualities might make it a substitute for gunpowder. However, it was too ex plosive. Two men died in a potassium chlorate explosion and Lavoisier aban doned the project. In 1781 he was elected to the Acad emy of Sciences against the opposition, for some reason, of Fourcroy [366], and in 1794 was appointed professor at the ficole Normale. Unlike Lavoisier, he got along well with the revolutionaries. In 233 [347] LAPLACE
LAPLACE [347] 1798, while in Egypt on a business trip, he met Napoleon and attached himself to the rising star, teaching him chemis try. Napoleon eventually made him a senator and a count. Later, Berthollet voted for the deposition of Napoleon and the returning Bourbons made him a peer. His great service to chemistry was his realization in 1803 that the manner and rate of chemical reactions depended on more than just the attraction of one sub stance for another. The “affinities” of Bergman [315] were not enough. Sub stance A would react with Substance B and not with Substance C, though its affinity for Substance C was greater, if Substance B was present in sufficiently greater quantity. This was a foreshadow ing of the extremely important law of mass action. Here, however, Berthollet’s views were ignored and they did not enter the mainstream of chemistry until the rise of the physical chemists, three quarters of a century later. Berthollet also maintained that the composition of the products of a reac tion varied with the relative masses of the substances taking part in the reac tion, but in this respect he was proved wrong by Proust [364]. This, unfortu nately, helped discredit his sound views on mass action. He was wrong, also, in his views on the nature of heat, which he considered a fluid, in opposition to the more accurate view of men such as Rumford [360]. [347] LAPLACE, Pierre Simon, mar quis de (la-plahs') French astronomer and mathe matician
Born: Beaumont-en-Auge, Calvados, March 28, 1749 Died: Paris, March 5, 1827 Not much is known of Laplace’s early life, because he was one scientist who was a snob and, ashamed of his origins, spoke little of them. It is usually stated that he came of a poor family and that well-to-do neighbors helped the obvi ously bright boy get an education. Re cent researchers, however, indicate he may have been of comfortable middle- class birth. At eighteen he was sent to Paris with a letter of introduction to D’Alembert [289], who refused to see him. Laplace sent him a paper on mechanics so excel lent that D’Alembert was suddenly over joyed to act as his sponsor. He obtained for the young man a professorship in mathematics. Early in his career Laplace worked with Lavoisier [334], determining specific heats of numerous substances. In 1780 the two men demonstrated that the quantity of heat required to decompose a compound into its elements is equal to the heat evolved when that compound is formed from its elements. This can be considered the beginning of ther mochemistry and as another pointer— following the work of Black [298] on la tent heat—toward the doctrine of con servation of energy, which was to come to maturity six decades later. However, Laplace turned his chief powers to a study of the perturbations of the members of the solar system and to the question of the general stability of that system, the problem that was al ready exercising Lagrange [317]. In 1787 Laplace was able to show the moon was accelerating slightly more than could earlier be explained. This he attributed to the fact that the eccen tricity of the earth’s orbit was very slowly decreasing as a result of the gravi tational influence of other planets. This meant a slightly changing gravitational influence of the earth upon the moon, which was not earlier allowed for and which could account for the moon’s trifling quantity of extra acceleration. He also studied certain anomalies in the mo tions of Jupiter and Saturn and, by building on some of Lagrange’s work, showed that they could be accounted for by the gravitational attraction of each planet upon the other. Laplace and Lagrange, working sepa rately but cooperatively, managed to generalize matters and show, for in stance, that the total eccentricity of the planetary orbits of the solar system had to stay constant, provided all planets revolve about the sun in the same direc 234 [347] LAPLACE
LAPLACE [347] tion (which they do). If the orbit of one planet increases its eccentricity, that of others must decrease in eccentricity sufficiently to strike a balance. The same sort of constancy holds for the inclina tion of a planet’s orbit to the plane of the ecliptic. The total stock of either ec centricity or inclination in the entire solar system is so small that no one planet could change its orbital charac teristics very much even if it drew upon the entire supply. This showed that as long as the solar system remained effectively isolated, and as long as the sun did not change its na ture drastically, the solar system would remain much as it is now for an indef inite period in the future. In this way Laplace rounded off the work of Newton [231], at least as far as planetary astronomy is concerned, and he is sometimes called the French New ton in consequence. Further refinements had to wait for men such as Leverrier [564] fifty years later and Poincare [847] fifty years later still. Laplace summed up gravitational theory in a monumental five-volume work called Celestial Mechanics, which appeared over the time interval from 1799 to 1825. His work was not inter rupted significantly by the political changes that swept France in that pe riod, including the rise and fall of Napo leon, even though he dabbled in politics. His prestige protected him and so did his ability to apply his mathematics to prob lems involving artillery fire. He also dis played a not-altogether-admirable ability to change his political attitude to suit changing circumstance. Another unattractive facet of La place’s personality was that he (like La voisier) was reluctant to give credit to others. He did less than justice to La grange’s contributions to their joint work on celestial mechanics, something the gentle Lagrange didn’t seem to mind. Napoleon made Laplace minister of interior, and when the astronomer proved incompetent in that post, he was promoted to the purely decorative posi tion of senator. Yet when Louis XVIII came to the throne after Napoleon’s fall, Laplace was not penalized for attaining office under Napoleon, as Haiiy [332] and Chaptal [368] were, but was made a marquis. Other honors were his. He had been elected to the Academy of Sciences in 1785, but that was rather to be ex pected. In 1816 he was elected to the far more exalted and exclusive literary soci ety, the French Academy, and in 1817 became president of that body.
torious for its habit of stating that from Equation A “it is obvious” that Equa tion B follows—except that students must often spend hours and days deter mining just why it is so obvious. Napo leon is supposed to have remarked, on leafing through this book, that he saw no mention of God. “I had no need of that hypothesis,” said Laplace. When La grange heard this, he said, “Ah, but it is a beautiful hypothesis just the same. It explains so many things.” In pure mathematics Laplace wrote a treatise on the theory of probability be tween 1812 and 1820 that gave this por tion of mathematics its modem form. Oddly enough Laplace is best known for a speculation he published as a note at the end of later editions of a non mathematical book on astronomy meant for the general public, a speculation that he did not himself take any too seriously. Since all the planets revolve about the sun in the same direction and in just about the same plane, Laplace suggested that the sun originated as a giant nebula or cloud of gas that was in rotation. As the gas contracted, the rota tion would have to accelerate and an outer rim of gas would be left behind (by centrifugal force). The rim of gas would then condense into a planet. With continued contraction, this would hap pen over and over until all the planets were formed, still moving in the direc tion of the original nebular rotation. The core of the nebula finally would con dense into the present-day sun. This nebular hypothesis caught the fancy of astronomers and remained pop ular throughout the nineteenth century as the favored explanation of the origin of the solar system. After a period of eclipse in the first few decades of the twentieth, it returned about mid-century 235 [3481 JENNER
JENNER [348] in Weizsacker’s [1376] modified form to greater popularity than ever. Possibly unknown to Laplace, a simi lar suggestion, not quite as thoroughly worked out, had been advanced forty years earlier by Kant [293]. [348] JENNER, Edward English physician
May 17, 1749 Died: Berkeley, January 26, 1823 Jenner was the son of a clergyman and lost his father and mother when he was only five. Under the guardianship of an elder brother, he had some schooling and was then apprenticed to a surgeon in 1762. He eventually obtained his medi cal degree from St. Andrew’s in 1792. His interests ranged far beyond medi cine, however, into music, poetry, and natural history. He was sufficiently com petent in the last to be given the job of preparing and arranging zoological speci mens collected by Captain Cook [300] after his first voyage to the Pacific. He was even offered a post as naturalist on the second voyage, but he refused, pre ferring to remain in practice at home. In medicine Jenner’s chief interest was smallpox, one of the most dreaded dis eases of its time. Almost everyone got it, in varying degrees of virulence, and in bad epidemics as many as one out of three died. The survivors were usually pockmarked, their skin pitted and scarred. The disfiguration at its worst al most robbed a face of any appearance of humanity. Many feared such disfigura tion worse than death. A very mild case of smallpox was far better than none at all, for once the pa tient recovered he became immune to all future attacks. In Turkey and China there were attempts to catch the disease from those with mild cases. There was even deliberate inoculation with matter from the blisters of such cases. Unfortu nately one could not always guarantee that the disease would be mild in the new host, so that this sort of inoculation was a rather grisly form of Russian roulette. Nevertheless, the notion was making an impression on western Europe. Diderot [286], for instance, sup ported it ardently. In the early eighteenth century that Turkish habit of inoculation had been in troduced into England. It did not catch on, but inoculation was much in the air and as early as 1775 it set Jenner think ing. There was an old wives’ tale current in Gloucestershire that anyone who caught cowpox (a mild disease of cattle resembling smallpox) was immune not only to cowpox but also to smallpox. Jenner wondered if it might not be true. He observed a disease of horses called the grease, in which there was a swelling and blistering in part of the leg. People working in stables and barnyards might get some blisters of their own this way, and they too seemed rarely to get small pox. It was something that had to be tested and the test was a fearsome one. On May 14, 1796, Jenner found a milkmaid, Sarah Nelmes, who had cowpox. He took the fluid from a blister on her hand and injected it into a boy, named James Phipps, who of course got cowpox. Two months later he inoculated the boy again, this time with smallpox. Had the boy died or even been badly sick, Jenner would clearly have been a criminal. The boy did not die; the smallpox did not touch him; and Jenner was a hero. Jenner wanted to try it again to make sure, but it took him two years to find someone else with active cowpox. In 1798 he was able to repeat his experi ment with equally happy results and finally he published his findings. The Latin word for cow is vacca and for cowpox, vaccinia. Jenner coined the word vaccination to describe his use of cowpox inoculation to create immunity to smallpox. He had, in this way, founded the science of immunology. So widespread was the dread of small pox that the practice of vaccination was accepted quickly and spread to all parts of Europe. The British royal family was vaccinated, and the British Parliament, never noted for wild generosity, voted Jenner £10,000 in 1802 (and another
Download 17.33 Mb. Do'stlaringiz bilan baham: |
ma'muriyatiga murojaat qiling