Biographical encyclopedia
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351 [532] LIEBIG
ERICSSON [533] that was formed. By 1831 Liebig had taken this technique in hand and per fected it to the point where, from the figures on carbon dioxide and water formed, accurate measurements of the carbon and hydrogen in the original compound could be obtained. Dumas [514] added a satisfactory method for determining nitrogen, and the Liebig- Dumas method of quantitative organic analysis remained in effect, almost un touched, until the development of micro methods of analysis by Pregl [982] some three quarters of a century later. In 1824 Liebig had begun to teach at the university in the small Hessian city of Giessen and there he proved himself one of the great chemistry teachers of all time. He established a laboratory for general student use (an innovation) and was the intellectual father and grand father of most of the chemists since his time. Giessen became the chemical cen ter of the world for a quarter century, and helped make Germany chemically supreme in the latter half of the nine teenth century. In 1845 Liebig was created a baron. In 1852, his health having worsened, he ac cepted an appointment at the University of Munich on condition that he need not be expected to teach, and remained there for the rest of his life. In the latter half of his career Liebig became interested in biochemistry. He applied his analytic abilities to the exam ination of tissue fluids such as blood, bile, and urine. He maintained and helped establish the view that body heat and vital activity arose out of the energy derived from the oxidation of foodstuffs within the body, and declared carbohy drates and fat—rather than carbon and hydrogen as Lavoisier [334] had thought —the fuel of the body. In this he was proved correct. He also believed, as Berzelius did, that fermentation was a purely chemical phenomenon, not in volving life. He engaged in a long dis pute with Pasteur [642] on this subject and here Liebig was proved to be wrong. He also concerned himself with agri cultural chemistry, after the British As sociation for the Advancement of Sci ence had happened to ask him to pre 352 pare a report on the subject. He main tained (correctly) that the chief factor in the loss of soil fertility was the con sumption by the plant of the mineral content of the soil; that is, of compounds containing elements essential to life, such as sodium, potassium, calcium, and phos phorus. He was the first to experiment with fertilization through the addition of chemical fertilizers in place of natural products such as manures. Unfortu nately, he was of the opinion that plants generally obtained their nitrogen from the atmosphere, as Boussingault [525] had shown that peas and beans did. Therefore, Liebig did not add nitrogen compounds to his chemical fertilizers and they did not succeed in promoting fertility. Eventually though, this mistake was rectified. The use of chemical fertilizers has not only greatly multiplied the food supply of those nations making use of scientific agriculture but also helped re duce epidemics through the elimination of the ubiquitous manure pile. [533] ERICSSON, John Swedish-American inventor Born: Långbanshyttan, Varm land, Sweden, July 31, 1803 Died: New York, New York, March 8, 1889 After a six-year hitch as an engineer ing officer in the Swedish army, Erics son, the son of a mines inspector, re signed and devoted himself to inventions. In 1826 he went to England and tried his hand at devising a steam locomotive. In this he was beaten by Stephenson [431], but in 1836 he devised the screw propeller, which replaced the huge pad dle wheel as a propulsive device for steamships. For die first time it was practical to apply steam propulsion to war vessels, since the paddle wheel had till then made entirely too large and vul nerable a target. In 1839 he came to the United States and built a screw-propelled vessel for the American navy. One of the guns on this vessel, the U.S.S. Princeton, exploded
[534] DOPPLER
CHALLIS [535] while government officials were inspect ing it and a number were killed. Presi dent John Tyler himself had a narrow escape. This damaged Ericsson’s reputa tion for a while, though the explosion was in no way his responsibility. He stayed in this country and became an American citizen in 1848. This was fortunate, for in 1861 he built the Moni tor, an ironclad vessel, the plans of which Napoleon HI of France had turned down. It was launched just in time for it to sail south to battle to a draw the Confederate navy’s ironclad
South would have broken the Northern blockade and, with English help, might have gone on to win the Civil War. The battle of the Monitor and the Merrimac at Hampton Roads, Virginia, ended at a stroke the supremacy of the wooden vessel and introduced the era of the mod ern navies of metal (even though both ships were, in essence, destroyed in the battle). A year after his death his body, at the request of the Swedish government, was sent back to the land of his birth. He was buried there. [534] DOPPLER, Christian Johann (dohp'ler) Austrian physicist Born: Salzburg, November 29, 1803
Died: Venice, Italy (then under Austria), March 17, 1853 Doppler, the son of a master mason, was lost to America by a hair. In 1835, despairing of getting an academic ap pointment, he made ready to emigrate to the United States. At the last moment he received word of the offer of a profes sorship in mathematics at a school in Prague and abandoned his plans for emi gration. After the revolutionary turmoils of 1848 and 1849, Doppler in 1850 took a position in Vienna where he felt more secure.
His name is forever associated with the Doppler effect, that phenomenon in which a moving sound source seems more highly pitched to someone whom it is approaching than to someone moving with the source; and more deeply pitched to someone from whom it is moving away than to someone moving with the source. The most familiar ev eryday example is the behavior of the sound of the locomotive whistle as the train passes by someone standing at a station. From a high pitch it drops sud denly to a low one. Doppler explained the phenomenon correctly by pointing out that the sound waves partake of the motion of the source and reach the ear at shorter inter vals when the source is approaching— hence higher pitch. When the source recedes, the waves reach the ear at longer intervals—hence lower pitch. In 1842 he worked out a mathematical relationship, relating the pitch to the rel ative motion of source and observer. This was tested by a rather bizarre ex periment in Holland a couple of years later. For two days a locomotive pulled a flat car back and forth at different speeds. On the flat car were trumpeters, sounding this note or that. On the ground, musicians with a sense of abso lute pitch recorded the note as the train approached and as it receded. Doppler’s equations held up. Doppler predicted that a similar effect would hold for light waves but his expla nation of the behavior of light from a moving source was not quite accurate. This portion of the theory was worked out properly a few years later by Fizeau [620] and turned out to be of great im portance to astronomy. [535] CHALLIS, James English astronomer
12, 1803 Died: Cambridge, December 3, 1882
Challis graduated from Cambridge in 1825 and became director of the Cam bridge Observatory in 1836. In 1845 he was asked by Airy [523] to check the po sition predicted by J. C. Adams [615] as one in which a possible trans-Uranian planet might be found. Challis did not wish to do this, feeling 353 [536] LENZ
SCHLEIDEN [538] that it was a waste of time and that it was much more important that he con tinue his work of hunting for comets. He therefore put off the job as long as he could, and then when procrastination could be continued no longer, he did the job in so dilatory a manner that he never bothered to compare the observations of one day with those of another to see if one of the stars had shifted position and was a planet. The result was that Galle [573] sighted the new planet, Neptune, first, and only after that did Challis, making use of hindsight, discover that he had observed Neptune twice, before Galle’s an nouncement, but had failed to know that through his own stupidity. In fact, Challis is only remembered in astronomy for this stupidity. That he himself lost credit for the discovery is of no account; that he helped lose Adams the credit is a tragedy.
[536] LENZ, Heinrich Friedrich Emil (lents)
Russian physicist Born: Dorpat, Estonia, (now Tartu, Estonian SSR), February 24, 1804
1865
Lenz, the son of a magistrate, had originally studied theology but grew in terested in science. Between 1823 and 1826, he accompanied a scientific ocean voyage around the globe as Darwin [554] was to do a few years later. He then spent most of his life as professor of physics at the University of St. Peters burg. Lenz was investigating electrical induc tion at about the same time as Faraday [474] and Henry [503] and was third in the field. He made a generalization in 1834 to the effect that a current induced by electromagnetic forces always pro duces effects that oppose those forces. This is Lenz’s law and is a general de scription of the phenomenon of self-in duction. Lenz’s law must be taken into account in the design of electrical equip ment. In 1833 Lenz also reported his discov ery of the manner in which the resis tance of a metallic conductor changes with temperature, increasing with rise of temperature, decreasing with its fall. [537] SIEBOLD, Karl Theodor Ernst von (zee'bohlt) German zoologist
ary 16, 1804 Died: Munich, Bavaria, April 7, 1885
Siebold was a member of a scientific dynasty, for his brother, father, uncle, and grandfather were all engaged in one or another of the biological sciences. Siebold himself received his medical de gree in 1828, practiced medicine briefly, then, with the advantage of a recom mendation from Humboldt [397], served as professor of zoology at various Ger man universities, ending at Munich. In 1845 he published a book on com parative anatomy in which he dealt in detail with protozoa. He made it quite clear that these consisted of single cells, thus supporting Dujardin [517] against Ehrenberg [491], and decisively so. The cell theory, which had recently been ad vanced by Schleiden [538] and Schwann [563], would therefore have to state that organisms were composed of “one or more cells” rather than merely “of cells.” Siebold was also the first to study cilia. He showed that unicellular creatures could use these for locomotion, whipping themselves through the water with these numerous hairlike projections. In higher animals, cilia, by their whipping, set up water currents. [538] SCHLEIDEN, Matthias Jakob (shly'den) German botanist
Schleiden, the son of a prosperous physician, was trained as a lawyer, ob taining his degree in 1822. At this work 354 [539] OWEN
OWEN [539] he was most unhappy, even attempting suicide. He found refuge in botany, working under J. Muller [522], and this became first his hobby, then his profes sion. He rebelled against the occupation of most botanists, which consisted of the ever more painstaking classification and subclassification of plants. Instead, he placed plant tissue under the microscope. This led him in 1838 to the elabora tion of the cell theory for plants, which Schwann [563] was to extend, more sys tematically, to animals the next year. Schleiden particularly recognized the im portance of the cell nucleus, discovered earlier that decade by Robert Brown [403], He sensed its connection with cell division but imagined (wrongly) that new cells budded out of the nuclear sur face. Schwann went along with Schleiden in this mistaken belief. Schleiden received a doctoral degree at the University of Jena in 1839. Although under the influence of the “nature phi losopher” school, which in the persons of Baer [478], Owen [539], and others, led the fight against Darwin [554], Schleiden was among the first of the German biol ogists to accept Darwinian evolution. He was a very successful science popu- larizer, both in lectures and in articles. [539] OWEN, Sir Richard English zoologist Born: Lancaster, July 20, 1804 Died: Richmond Park, London, December 18, 1892 Owen, the son of a merchant, obtained his medical degree in 1826 at the Uni versity of Edinburgh, after having served an apprenticeship to a surgeon. After graduation, however, he accepted a post as assistant to the conservator of the mu seum of the Royal College of Surgeons, which introduced him to the joys of zoo logical classification. This was sharpened and directed through a meeting with Cuvier [396], who visited London in 1830. Owen went on to study in Paris and caught the contagion of comparative anatomy. In 1856 he was appointed su perintendent of the Natural History De partment of the British Museum. He was Cuvier’s true successor through most of the nineteenth century. He dissected as many animals as he could. In 1852, while dissecting a rhinoc eros, he discovered the parathyroid glands. Another generation passed before they were discovered in man. In particu lar he was interested in comparing tooth structure, on which he wrote a large treatise in the early 1840s. This is by no means as odd as it might sound, for teeth are the hardest parts of the body and the most easily preserved in fossil form. From the teeth, moreover, a great deal can be learned about the feeding habits and the mode of life of a creature. Owen, through his interest in teeth, was directed to a study of fossils and ex tinct animals (paleontology), particu larly those of Australia and New Zea land. He was the first to describe the giant and recently extinct moas of New Zealand. At the other end of the scale, he was also the first to describe the para site (anything but extinct, alas) that Leuckart [640] was to show causes trich inosis in man. He was the first of the great dinosaur hunters, having coined the very word (“terrible lizard”) in 1842. In 1854 he prepared the first full-sized recon structions of dinosaurs for display at the Crystal Palace in London. The recon structions were quite inaccurate, we now know, because of the limited information that had been obtained, but they were very dramatic just the same and aroused enormous interest in the subject. He refused a knighthood in 1842 but accepted in 1884 at the time of his re tirement. The latter half of his career was marked by a violent hostility to the notion of evolution through natural se lection as advanced by Darwin [554], a hostility that caused him to go to the ex treme of writing anonymous articles in which were included deliberate distor tions and misquotations, and of feeding rabble rousers with antievolutionary ar guments. In this, he may have been mo tivated by personal jealousy of Darwin’s increasing fame, despite the fact that they had previously been good friends for twenty years. It was not so much that he was against
[540] WEBER
MOHL [542] evolution itself but that he was the last of the major “nature philosophers,” the school initiated by Oken [423] a half century earlier. Owen, therefore, had vi talistic notions of evolution’s taking place through internal forces within the cells. Evolution through natural selection was too rationalistic and seemed too much the product of blind chance to suit him. [540] WEBER, Wilhelm Eduard (vay'- ber) German physicist Born: Wittenberg, Saxony, Octo ber 24, 1804 Died: Gottingen, June 23, 1891 Weber, the younger brother of Ernst Weber [492], was appointed professor of physics at Gottingen in 1831. Young Weber had met Gauss [415] through the good offices of Humboldt [397] and it was at Gauss’s recommendation that the appointment was made. For most of his professional life, Weber then worked in collaboration with Gauss on the study of magnetic phenomena. In 1837 he and a number of other professors lost their posts because of their open opposition to the autocracy of the king of Hannover. Eventually he was reinstated. Gauss introduced a logical system of units for magnetism, related to the fun damental units of mass, length, and time. Weber did the same for electricity in 1846. These units were officially ac cepted at an international congress in Paris in 1881, at which Helmholtz [631] was a prominent delegate. The magnetic unit, weber, is named in his honor. With Gauss, Weber also constructed a practi cal telegraph in 1834, even before Henry [503] had managed to do so. In conjunction with his brother, Ernst, he studied the flow of liquids through tubes—knowledge that could be applied usefully to the human circulatory sys tem. Then, toward the end of his life, he grew interested in spiritualism, a weak ness of aged scientists at the turn of the century.
[541] JACOBI, Carl Gustav Jacob (yah-kohhee) German mathematician
ber 10, 1804 Died: Berlin, February 18, 1851 Jacobi, the son of a Jewish banker, was a precocious youth who was ready for university training at the age of twelve but was held back till the mini mum entrance age of sixteen. He then went to the University of Berlin and ob tained his Ph.D. in 1824 and was qualified for a teaching position at an important school despite the disad vantage of his religion. He gained a professorial position at the University of Königsberg in 1827, thanks in part to the praise of Legendre [358] for Jacobi’s work on elliptical functions, a subject Legendre had pio neered. Jacobi went on to develop the subject in full, independently of Abel [527] who was doing the same thing. He also pioneered in the development of de terminants, a useful technique in the ma nipulation of simultaneous equations. In 1848, during the revolutionary up heavals of that year, Jacobi fell under suspicion as a possible liberal. (His reli gion was undoubtedly of no help to him.) He had almost left for Vienna when Frederick William IV of Prussia decided the loss to Prussia would be too great and persuaded him to remain. However, Jacobi, who had developed diabetes, was not a well man and died not long after of smallpox. [542] MOHL, Hugo von (mole) German botanist
berg, April 8, 1805 Died: Tübingen, Baden-Württem berg, April 1, 1872 Mohl obtained his doctorate in 1828 at the University of Tübingen and then became a professor of botany there in 1835. He held the post till his death. He studied plant cells assiduously. In 1846 he felt it important to distinguish Download 17.33 Mb. Do'stlaringiz bilan baham: 
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