Biographical encyclopedia
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371 [563] SCHWANN
SCHWANN [563] He boldly supported Darwinism in America against the objections of reli gious leaders and debated the point vig orously with the antievolutionist, Agassiz [551], He himself was a prominent reli gious layman, which gave his point of view added force, since he could not be dismissed as an atheist. He maintained, in fact, that natural selection was not a random force but was guided by God. (Darwin disagreed with him here.) He was a professor of natural history at Harvard for thirty-one years, begin ning in 1842, and there he developed a botanical garden and library almost from scratch. Between 1863 and 1873 he was presi dent of the American Association for the Advancement of Science. In 1900 he was selected as one of those to be memori alized in the newly established Hall of Fame for Great Americans. [563] SCHWANN, Theodor (shvahn) German physiologist
December 7, 1810 Died: Cologne, Rhenish Prussia, January 11, 1882 After completing his medical training in 1834 Schwann served as assistant to Johannes Muller [522] and almost at once made an important discovery. Ever since the time of Réaumur [252] and Spallanzani [302], it had been known that digestion was a chemical process. When Prout [440] had discovered the presence of hydrochloric acid in the stomach it was naturally thought that the acid was what broke down foodstuffs. In 1834, however, Schwann prepared extracts of the glandular lining of the stomach and showed that, mixed with acid, it had a meat-dissolving power that was far greater than the acid alone would have had. In 1836, by treating the extract with mercuric chloride, he pre pared a precipitate that proved to be the active principle. He called it pepsin, from a Greek word meaning “to digest.” This substance was an example of what was then called a ferment and is now called an enzyme. Payen [490] had isolated an enzyme from malt extract three years earlier, but pepsin was the first enzyme to be prepared from animal tissue. Its discovery was one of the early turning points in the development of bio chemistry. Schwann devised some experiments at this time that tended to disprove the doc trine of spontaneous generation. In 1838 he showed yeast to be made up of tiny plantlike organisms and held that fer mentation of sugar and starch was the result of a life process, a view ridiculed by Berzelius [425], Wohler [515], and Liebig [532]. The work of Pasteur [642] a generation later was crucial in es tablishing Schwann’s correctness. Putting those to one side, then, what Schwann is best known for is his elaboration in 1839 of the cell theory. In its simplest form, this is the state ment that all living things are made up of cells or of material formed by cells, and that each cell contains certain essen tial components such as a nucleus and a surrounding membrane. Actually this be lief had been held more or less vaguely by a number of men in the preceding century, being one of those ideas that were “in the air.” In fact, the year be fore, Schleiden [538], with whom Schwann was well acquainted, had stated the cell theory in connection with plants as Schwann was doing in connection with animals. It was Schwann, however, who most clearly stated and summarized the case, and he (usually coupled with Schleiden) is usually credited with establishing the cell theory, as he himself called it. He also coined the term “metabolism” as representing the overall chemical changes taking place in living tissue. Schwann pointed out that plants and animals alike were formed out of cells, that eggs were cells distorted by the pres ence of yolk, that eggs grew and devel oped by dividing and redividing so that the developing organism consisted of more and more cells but always of cells. He refined Bichat's [400] conception of tissues by differentiating these in terms of the types and arrangement of cells
[564] LEVERRIER LEVERRIER
that made them up. In this connection, he discovered the “Schwann cells” that make up the nerve sheaths. The cell theory was extended by Nâgeli [598], Siebold [537], Kôlliker [600], and Gegenbaur [669], and was neatly summarized by Virchow [632], It was a landmark in the history of biology comparable to that formed by the atomic theory in chemistry. For one thing, the cell theory succeeded in luring the atten tion of biologists from the cell boundary (the first portion of the cell to be ob served by Hooke [223] and the easiest to study) to the all-important cell contents. Schwann became professor of anatomy at Louvain in 1838 and at Liège in 1847. In the last forty years of his life he gave way to mysticism and religious medita tions and did nothing to match his activi ties in the one decade of the 1830s, but that is scarcely something of which we have a right to complain. [564] LEVERRIER, Urbain Jean Joseph (luh-veh-ryay') French astronomer
1811
Died: Paris, September 23, 1877 Leverrier’s father, a minor civil ser vant, sold his house in order to put his son through college, and the results justified him. Leverrier began his profes sional life as a chemist in Gay-Lussac’s [420] laboratory and did promising re search on the compounds of phosphorus with hydrogen and oxygen. However, in 1836 he had the opportunity of taking a post as an astronomy teacher at the École Polytechnique, where he was working. Quite accidentally, then, he found himself an astronomer. He occupied himself with questions of celestial mechanics, continuing the work of Laplace [347] and demonstrating with even greater exactness the stability of the solar system. It was pointed out to him by Arago [446] that the motions of Mercury needed careful analysis, and Leverrier’s accurate calculations showed that the planet’s perihelion (the point in its orbit at which it most closely approached the sun) did indeed advance forty seconds of arc per century more than could be ac counted for by Newton’s [231] theory of gravitation, even after the minor perturb ing effects of the other planets had been allowed for. Leverrier decided in 1845 that there must be one planet that was not being taken into account. He postulated an as- yet-undiscovered planet (which he called Vulcan) with a diameter of a thousand miles and a distance from the sun of nineteen million miles. It would just ac count for the Mercurian anomaly, he believed. Some amateurs, such as Schwabe [466], had been searching for an intra-Mercurian planet even before Leverrier’s announcement. No such planet as Vulcan was found, though the neighborhood of the sun was inspected assiduously at every subse quent eclipse. It is now quite certain that such a planet does not exist. Others suggested a belt of asteroids while Asaph Hall [681] felt that the force of gravitation varied not quite as the square of the distance but as very slightly more than the square. Both hy potheses raised more difficulties than they solved and were given up. Nevertheless the worry over Mercury’s motion was not entirely fruitless, for in the case of Schwabe the result was the discovery of the sunspot cycle, some thing more important than a discovery of Vulcan. Leverrier’s work on Mercury gained him admission to the Paris Academy of Sciences in 1846, but he was on the threshold of much greater fame. The planet Uranus, discovered by Herschel [321] a little over half a cen tury before, was at that time the farthest known planet. Its motion, too, showed anomalies. It was 1.5 minutes of arc away from where it should be, according to the careful computations of Bouvard [392]. Arago urged Leverrier to work on this and in 1846 Leverrier again assumed an undiscovered planet, one beyond Uranus’ orbit (something several astron omers such as Bessel [439] and John
[564] LEVERRIER BUNSEN
Herschel [479] had previously suggested as a possibility). Such an outer planet would exert a gravitational force that those who calcu lated Uranus’ orbit had not allowed for. Leverrier calculated the size and position the unknown planet would have to oc cupy in the sky to account for the devia tions of Uranus from its calculated orbit. Unknown to Leverrier, a young En glish astronomer, J. C. Adams [615], had made the same calculations some months earlier and reached the same result. Le verrier was the more fortunate of the two, however. While Adams’s work was neglected at Cambridge University, the Frenchman was able to take action. He wrote to Galle [573] at the Berlin Obser vatory to thank him for some publica tions he had sent and asked him to look at a certain spot in the sky for the new planet. As it happened, everything was breaking right for Leverrier. Galle had just received a new and improved star map of the area and was therefore in a position to spot any intruding object eas ily.
On September 23, 1846, the very first evening of the search, a new planet was discovered very close to the predicted spot, even though both Leverrier and Adams had assumed Neptune to be con siderably more distant than it, in fact, proved to be, because they let themselves be guided by Bode’s [344] law. In the furor that followed there was a move ment among French astronomers, led by Arago, to name the planet “Leverrier” but wiser counsels prevailed and Lever rier himself named it, nonnationalis- tically, after Neptune, god of the ocean (supposedly because of the green color of the planet). Within a month Lassell [509] had discovered a large satellite of Neptune and named it Triton, after Nep tune’s (Poseidon’s) son in the Greek myths.
This discovery of a giant planet by pure calculation was the most dramatic achievement of Newtonian theory in all its history and removed the last shred of doubt (if any existed) of its validity. Leverrier participated enthusiastically in the Revolution of 1848 on the side of the republicans, but when Louis Napo leon came to power, Leverrier back tracked (unlike his old friend Arago). He supported Louis Napoleon even after the latter subverted republican principles and announced himself Emperor Napo leon III. After Arago’s death Leverrier was appointed director of the Paris Ob servatory in 1854. As director he tackled all the planets of the solar system and worked out a gravitational accounting of their motions with greater accuracy than ever before. Like Airy [523], Leverrier was an irascible and unpopular director who managed to squeeze a great deal of work out of those under him. He was so hated by those unfortunate enough to have to work for him that he was re moved from his position in 1870 by pop ular demand. When his successor died in 1873, Leverrier was restored, but with restricted powers. The motion of Mercury’s perihelion continued to be an elusive problem for a generation past his death and that re mained his one great failure. And yet this failure was more significant to the future of science than his success in the case of Neptune. The former was to upset Newton’s scheme of the universe, which the latter had seemed to establish so firmly. It was Mercury’s motion that was to be one of the observational props of Einstein’s [1064] general theory of relativity, three quarters of a century after Leverrier’s failure.
[565] BUNSEN, Robert Wilhelm Eberhard German chemist
Bunsen, the son of a professor of philology, obtained his education at the University of Gottingen. He studied under Strohmeyer [411] and earned his doctorate in 1830. After travels through France and Germany he turned to teach ing and for a while succeeded to Wohler’s post at the University of Cas
[565] BUNSEN
DRAPER [566] sell. By 1838 he had a professorial ap pointment at the University of Marburg. In 1852, when Gmelin [457] died, Bun sen succeeded to his post at Heidelberg. Bunsen’s long life is exclusively the history of his chemical researches, for he was one of those scientists who never married. The excuse he gave was the same as Dalton’s [389], that he never had the time. This was certainly not meant entirely humorously for his work was as exacting as any family could have been, and not always kind in its treat ment of him, either. In his late twenties he began his work by studying organic arsenic-containing compounds (a group of substances that were to come into world prominence three quarters of a century later, when Paul Ehrlich [845] successfully devel oped chemotherapy based on them). In an explosion in 1836, during the course of that work, he lost an eye and twice nearly died of arsenical poisoning through inhalation and slow absorption of the material with which he worked. He finished his researches but never worked in organic chemistry again, nor would he allow it to be taught in his lab oratory. Nevertheless, the work that had nearly proved fatal to him inspired his student Frankland [655] to move further in this direction. His interests in inorganic chemistry, however, were extremely varied. He in vestigated the gases produced in blast furnaces and suggested methods for cut ting down heat loss. In the process he also invented new methods of gas analy sis. He invented various calorimeters for the measurement of heat (an interest that led him to a dramatic investigation of the geysers in Iceland in the late 1840s and resulted in his accurate expla nation of their workings). He also in vented a carbon-zinc battery and a grease-spot photometer for measuring light. He was the first to produce mag nesium in quantity and showed how it could be burned to produce an extremely bright light that proved to be of great as sistance to photography. Bunsen is well known for a burner that he first used in 1855. It was perfo rated at the bottom so that air was drawn in by the gas flow. The resulting gas-air mixture burned with steady heat and little light, without smoke or flicker ing. He was not the first to use such a burner (a similar one was used by Fara day [474]), but he popularized it to such an extent that anyone who has ever worked in a high school chemistry labo ratory remembers his Bunsen burner even if he has forgotten everything else. The work for which he was most re nowned, however, was the result of the ingenuity and insight of his younger co worker, Kirchhoff [648]. Together, Bun sen and Kirchhoff invented the technique of spectroscopy in 1860 and almost at once discovered two new elements, ce sium and rubidium. Other men, such as Draper [566] and Huggins [646], were then to turn that instrument on the heavens. [566] DRAPER, John William English-American chemist
England, May 5, 1811 Died: Hastings-on-Hudson, New York, January 4, 1882 Draper, the son of a minister, studied at the University of London and then in 1833 emigrated to the United States. He obtained a medical degree at the Univer sity of Pennsylvania in 1836. There, Hare [428] was one of his teachers. He taught chemistry at New York Univer sity in 1838, helped organize a medical school, and taught chemistry and physi ology there. Eventually he became presi dent of the medical school. Under his leadership, New York Uni versity became one of the first schools in America to award Ph.D. degrees. Despite all this, he is best known in fields far removed from the medical. He recognized that light brought about chemical reactions through absorption by the molecules of light energy, thus prov ing to be a pioneer in photochemistry. He also recognized the fact that all sub stances at about 525°C glowed a dull 375 [567] SIMPSON
GROVE [568] red (this is called the Draper point) and that with further rise in temperature more and more of the visible light region was added until the glow was white. He published his experiments in this field in 1847 and this was eventually to lead to the quantitative treatment by Wien [934] a half century later. From photochemistry his interest moved to photography and spectroscopy. He was one of the earliest photographers and took portraits of human beings, managing to cut the exposure time to under a minute. One of his photographs, taken in 1840, is the oldest surviving photographic portrait. A little earlier than 1840 he photo graphed the moon, and this was the first astronomical photograph. When he pho tographed the solar spectrum soon after, he was the first to show that spectral lines existed in the ultraviolet and infra red as well as in the visible portion of the spectrum. He also showed that some of the lines in the solar spectrum were produced by the earth’s atmosphere. Draper was one of the first to produce photomicrographs, taking photographs of what one could see under a microscope and reproducing them in a book on physiology which he published in 1856. In 1876 he was elected the first presi dent of the American Chemical Society. [567] SIMPSON, Sir James Young Scottish obstetrician Born: Bathgate, Linlithgow, June 7, 1811 Died: London, May 6, 1870 Simpson, the son of a baker, was a young prodigy, entering the University of Edinburgh at fourteen. He gained his medical degree at twenty-one with a graduation thesis so good that it promptly won him an appointment as as sistant to one of the professors at the university. He was appointed professor in his own right (of obstetrics) in 1840, and was one of the founders of modem gynecol ogy. He conducted a successful practice and, in 1846, upon hearing the news of anesthesia in America, promptly adopted it. He had a little trouble with ether and used chloroform instead. (Chloroform is much more dangerous and ether won out in the end.) Simpson was the first to use anesthesia in childbirth and this met with considerable criticism from those ardent souls who believed that the pain of child birth was decreed by God as part of the curse of Eve. Simpson pointed out that God did not rejoice in pain and that when he extracted a rib from Adam to make Eve, he first caused a “deep sleep” to fall upon him. Simpson’s victory was clear when he was appointed Queen Vic toria’s official physician. In 1853 he utilized chloroform in helping Victoria through the pain of childbed, delivering her seventh child, Prince Leopold, and that stilled all criti cism. Simpson was made a baronet in 1866 and would have been buried in Westminster Abbey had not his family refused the honor. [568] GROVE, Sir William Robert British physicist Born: Swansea, Wales, July 11, 1811
Died: London, August 1, 1896 Grove qualified as a barrister in 1835, after an education at Oxford, but he was in poor health and didn’t feel up to the rigors of a legal practice. He retired therefore to the quieter and apparently less demanding life of a gentleman ex perimenter. In 1839 he devised an electric cell making use of hydrogen and oxygen. Until then (and since, too) the electric cells that have been put into practical use have relied upon more or less expen sive metals such as zinc, lead, nickel. It would be much less expensive to use ordinary fuels such as hydrogen; better yet, natural gas; still better, coal dust. If these were oxidized in an electrical cell, producing electricity directly, small-scale electrical conduction would become un precedentedly cheap. The “Grove cell” was the first of these fuel cells and earned him a membership in the Royal
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