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521 [804] KOVALEVSKY HEAVISIDE
tive to negative) the current would pass only half the time, when filament was negative and plate positive, and not the other half. Alternating current would enter the device but direct current would leave. In 1904 he had thus developed a rectifier. He called it a valve, since it turned on for current in one direction and off for the current in the other. In the United States, for some reason, it came to be called a tube. De Forest’s [1017] addition of a grid that would make the tube an amplifier, as well as a rectifier, was the final touch needed to make electronic instruments practical. Fleming was knighted in 1929 and his long life of nearly a century made it pos sible for him to see the consequences of his little rectifier to the full. [804] KOVALEVSKY, Sonya (kov-uh- lefsky) Russian mathematician Born: Moscow, January 15, 1850 Died: Stockholm, Sweden, Febru ary 10, 1891 Kovalevsky, the daughter of a general, had the childhood and education of an aristocratic Russian woman of tsarist times—which meant that there was a limit as far as intellectual matters were concerned, as there was (for women) everywhere else in Europe. Kovalevsky married at eighteen; but that was a device to get away from parental supervision and go to Germany, where she could not attend university lectures (for the crime of being femi nine) but where Weierstrass [593], cap tivated by her obvious talent, tutored her privately. She worked on partial differential equations, where she managed to im prove on the great Cauchy [463]; on in tegrals, where she improved on Abel [527]; and on the mathematical consid eration of Saturn's rings, where she im proved on Laplace [347] and Maxwell [692]. She received a Ph.D. in absentia from Gottingen and won prizes for her work where the cash value was increased
because of the unusual merit they showed. She was elected to both the Swedish and Russian Academy of Sci ences despite her sex and then, with her ability still at its height, she died of pneumonia. [805] GAFFKY, Georg Theodor August (gafkee) German bacteriologist Born: Hannover, February 17, 1850
Died: Hannover, October 23, 1918
Gaffky, the son of a shipping agent, served as a hospital orderly in the Franco-Prussian War in 1870. Returning thereafter to his interrupted studies, he obtained his medical degree from the University of Berlin, in 1873. Gaffky accompanied Koch [767] to Egypt and India in 1883 and 1884. In 1884 he made his own chief contribution by isolating a bacillus and demonstrating it to be the causative factor of typhoid fever.
In 1888 he was appointed professor of hygiene at the University of Giessen. He continued to be interested in cholera (the trip to India was for the purpose of studying the disease) and it seemed less exotic when an epidemic of the disease broke out in Hamburg in 1892. He made another trip to India in 1897 and in 1904 was appointed director of the Insti tute for Infectious Diseases at Berlin. Dining World War I he served as ad viser to the government on hygiene and public health, dying just too soon to see Germany go down in defeat. [806] HEAVISIDE, Oliver English physicist and electrical en gineer
ruary 3, 1925 Heaviside was the son of an artist. Like Edison [788], he had no formal ed [807] SHARPEY-SCHÄFER BRAUN
ucation past the elementary level, be came a telegrapher, and was hampered by deafness. With the encouragement of his uncle (by marriage), Charles Wheat stone [526], he inaugurated a program of self-education that succeeded admirably. He could concentrate on it the more since he never married and lived with his parents till they died. He did important work in applying mathematics to the study of electrical circuits and extended Maxwell’s [692] work on electromagnetic theory. Perhaps because of his unorthodox education, he made use of mathematical notations and methods of his own that were greeted by other (and lesser) physicists with dis dain. For instance, he used vector nota tion where many physicists, notably Kel vin [652], did not. It was Kelvin, how ever, who first brought Heaviside’s work to the notice of the scientific community. Heaviside was forced to publish his papers at his own expense because of their unorthodoxy. After the discovery of radio waves by Hertz [873], Heaviside applied his mathematics to wave motion and published a large three-volume work, Electromagnetic Theory. In it he predicted the existence of an electrically charged layer in the upper atmosphere just months after Kennelly [916] had done so. This layer is now often referred to as the Kennelly-Heaviside layer. Heaviside spent his last years poor and alone and died, finally, in a nursing home.
[807] SHARPEY-SCHAFER, Sir Ed ward Albert English physiologist
2, 1850
Died: North Berwick, Scotland, March 29, 1935 Sharpey-Schafer, the son of a German immigrant, was bom with only the last half of his name, but at the University of London, he had William Sharpey as his teacher in anatomy and physiology. He was sufficiently impressed to prefix the latter’s name to his own in 1918, in order to perpetuate it. He developed the prone-pressure method of artificial respiration, the one we have all seen performed in demon strations until mouth-to-mouth resusci tation came into use. Sharpey-Schafer’s most significant work was the demonstration, in 1894, that an extract of the adrenal glands would act to raise blood pressure. This led to the isolation of adrenaline by Takamine [855] seven years later which in turn helped the evolution of the hor mone concept by Bayliss [902] and Star ling [954], In 1916 Sharpey-Schafer suggested that the hormone whose existence he suspected in the secretions of the islets of Langerhans [791] be named “insulin” from the Latin word for island. When the hormone was discovered six years later by Banting [1152] and Best [1218] that name was used over the discoverers’ own preference for “isletin.” Outside the regular performance of his duties as physician and scientist, Shar pey-Schafer was an indefatigable fighter for equal opportunities for women in medicine. During World War I, he attempted to fight against anti-German hysteria in En gland, and he drew down denunciations on his head from the superpatriots— even though both his sons died fighting for Britain in the war. [808] BRAUN, Karl Ferdinand (brown) German physicist Born: Fulda, Hesse-Nassau, June 6, 1850
Died: New York, New York, April 20, 1918 Braun obtained his doctorate at the University of Berlin in 1872 under Helmholtz [631], he was appointed pro fessor of physics at the Technical Uni versity of Karlsruhe and in 1885 moved on to the University of Tübingen, then in 1895 to the University of Strasbourg. In 1897 he modified the cathode-ray 523 [809] RICHET
RICHET [809] tube so that the spot of green fluores cence formed by the stream of speeding electrons was shifted in accordance with the electromagnetic field set up by a varying current. Thus was invented the oscillograph, by means of which fine variation in electric currents could be studied and which was the first step, as it turned out, toward television. As early as 1874 he had noted that some crystals transmitted electricity far more easily in one direction than in the other. Such crystals could therefore act as rectifiers, converting alternating cur rent, which forever doubled on its own tracks, into direct current. The crystals came to be essential to the crystal-set ra dios until they were replaced by De For est’s [1017] superior triodes. However, crystal rectifiers came into their own again, with sophisticated modifications, in the form of the solid- state systems devised by Shockley [1348] and his co-workers a half century later. Braun’s improvements in radio tech nology earned him the 1909 Nobel Prize in physics, which he shared with Mar coni [1025]. He visited the United States during World War I in connection with patent litigation. When the United States entered the war, he was detained in New York as an enemy alien and died before the war’s end would have made it possi ble for him to return home. [809] RICHET, Charles Robert (ree- shay') French physiologist Born: Paris, August 26, 1850 Died: Paris, December 3, 1935 Richet was the son of a physician and followed in his father’s footsteps, obtain ing his medical degree in 1877 at the University of Paris. In 1887 he was ap pointed professor of physiology there. Richet was versatile, writing on many subjects both in and out of science. As a young man he published a book of po etry under a pseudonym and in later years wrote novels and plays. He was an active pacifist, writing extensively on the problems and necessity of maintaining peace.
In 1887 Richet conceived the notion of producing an immune serum; that is, of injecting into an animal a particular substance to which it could then produce an antidote. (The injected material is an antigen; the countermaterial produced is an antibody.) If the antigen is a bac terium or a bacterial toxin, then an an tibody will exist that will prevent future infections. If serum containing this an tibody is then injected into a human being, it may lend him immunity to a particular disease. Richet tried to pro duce such an immune serum for tubercu losis but failed. Behring [846], working along similar lines, succeeded with diph theria. Richet continued work in this direc tion, however, and about the turn of the century discovered, rather to his sur prise, that sometimes a second dose of antigen put an animal into fatal shock. The antibody the animal had produced, far from protecting him, killed him. In 1902 Richet named this phenomenon anaphylaxis, from Greek words meaning “overprotection.” From then on, physicians were warned. Serum therapy had to be con ducted in such a way as to prevent this possibility of sensitization that would produce serum sickness. Preliminary tests to determine the degree of sensitiza tion of a particular patient must precede the administration of sera or, sometimes, even of such things as antibiotics. Fur thermore, natural sensitization to any of the myriad antigens that abound in na ture (in plant pollen, in food) can pro duce unpleasant reactions when mild doses of the antigen are encountered by the sensitized person. These reactions were termed “allergies,” a word intro duced in 1906, and the scientific study of allergic phenomena dates from Richet’s work.
In 1913, for his work on anaphylaxis, Richet was awarded the Nobel Prize in medicine and physiology. In his later years he grew interested in telepathy and other manifestations of what is now called extrasensory perception. In this, 524 [810] RIGHT
LE CHATELIER [812] he had the company of other scientists of the time, but nothing noteworthy came of it. [810] RIGHI, Augusto (ree'gee) Italian physicist Born: Bologna, August 27, 1850 Died: Bologna, June 8, 1920 Righi studied at the University of Bo logna, graduating in 1872. He taught at the University of Palermo, then at the University of Padua, returning to Bo logna in 1889 and remaining there till his death. He was interested in electromagnetic radiations and soon after Hertz’s [873] experiments was able to show that the shorter Hertzian waves, at least, dis played the phenomena of reflection, re fraction, polarization, and interference, in the same fashion that light did. This was the final proof that radio waves differed from light, not in nature, but only in wavelengths. Such experi ments finally established the existence of the electromagnetic spectrum. [811] GOLDSTEIN, Eugen (golt'shtine) German physicist
wice, Poland), September 5, 1850 Died: Berlin, December 25, 1930 Goldstein worked at the University of Berlin, where he obtained his Ph.D. in 1881 with Helmholtz [631], and then es tablished a laboratory of his own at the Potsdam Observatory. He studied the lu minescence produced at the cathode in an evacuated tube, as Pliicker [521] had a couple of decades earlier; but in 1876 Goldstein was the first to apply the name “cathode rays” to them. In 1886 he used a perforated cathode and found that there were rays going through the channels in the direction op posite to that taken by the cathode rays. He called these Kanalstrahlen (“channel rays” or, as they were more often called, “canal rays”). In 1895 Perrin [990] showed they consisted of positively charged particles and in 1907 J. J. Thomson [869] termed them “positive rays.” The study of the positive rays led eventually to the recognition by Ernest Rutherford [996] of the existence of the proton. [812] LE CHÂTELIER, Henri Louis (luh shah-tuh-lyayO French chemist Born: Paris, October 8, 1850 Died: Miribel-les-Echelles, Isère, September 17, 1936 Le Châtelier’s college training was in terrupted by the Franco-Prussian War and when he returned, it was to special ize in mining engineering. (His father had been inspector general of mines for France, so this might be considered a natural decision.) After graduating, he obtained a post as professor of general chemistry at the School of Mines in 1877. He was interested in the chemistry of cement, of ceramics, and of glass. He also studied the chemistry and physics of flames with a view to preventing mine explosions. This led him to study heat and its measurement. In 1877 he suggested the use of a thermoelectric couple for mea suring high temperatures. This consisted of two wires, one of platinum and one of platinum-rhodium alloy, bound together at the ends. If one end is heated, a tiny current is set flowing through the wire, the strength of the current being propor tional to the temperature. He also in vented an optical pyrometer designed to measure high temperatures by the nature of the light radiated by the hot object. A study of heat naturally led him into thermodynamics. This brought him to that for which he is best known, the enunciation of a rule, in 1888, that is still called Le Châtelier’s principle. This may be stated: “Every change of one of the factors of an equilibrium brings about a rearrangement of the system in such a direction as to minimize the origi nal change.” In other words, if a system in equilib rium is placed under what would or
[813] BUCHNER
MILNE [814] dinarily be increased pressure, it rear ranges itself so as to take up as little room as possible. Because of this the pressure does not increase as much as it would seem it should. Again, if the tem perature is raised, the system undergoes a change that absorbs some of the addi tional heat so that the temperature does not go up as much as would be in dicated. This is a very general statement that includes the famous law of mass action, enunciated by Guldberg [721] and Waage [701], and fits in well with Gibbs’s [740] chemical thermodynamics. (In fact, so general is that statement that it can be applied, with amusing success, to human behavior.) Le Chåtelier’s principle, by forecasting the direction taken by a chemical reac tion to a particular change of condition, helped rationalize chemical industries and guide chemists in producing desired products with a minimum of waste. Knowledge of this principle helped Haber [977], for instance, to devise his reaction that would form ammonia from atmospheric nitrogen, a crucial discovery for both peace and war, and one which Le CMtelier himself anticipated in 1901, nearly twenty years before Haber. Le Chatelier was one of the Europeans who discovered Gibbs, and was the first to translate him into French. He, like Roozeboom [854], devoted himself to working out the implications of the phase rule experimentally. In later life, he corresponded with Taylor [864] and labored to introduce his time-study methods into French in dustry.
[813] BUCHNER, Hans Ernst Angass German bacteriologist Born: Munich, Bavaria, Decem ber 16, 1850 Died: Munich, April 8, 1902 Although he is now best known as the brother of Eduard [903] (whose Nobel Prize award he did not live to witness), Hans won victories in the battle of sci ence on his own. He obtained his M.D. in 1874 and was professor of hygiene at the University of Munich from 1892. In his researches on immunity, he noted that protein in blood serum was of importance in this connec tion. He was thus a pioneer in the study of gamma globulins, those natural weap ons out of which the body fashions an tibodies with which to neutralize and render harmless invading microor ganisms. He also devised methods for studying anaerobic bacteria, those that grow in the absence of air. [814] MILNE, John English geologist
1850
Died: Shide, Isle of Wight, July 30, 1913 Milne studied at the Royal School of Mines and became a mining engineer. A traveler from youth, he visited Iceland and Labrador, then joined an expedition to Egypt, Arabia, and Siberia as a geolo gist.
His real chance came in 1875, how ever, when he accepted an appointment as a professor of geology and mining in the Imperial College of Engineering at Tokyo. He reached Japan after an ele ven-month journey across Asia, then remained there for twenty years and had a marvelous opportunity to study earthquakes, for no land is more riven with them than Japan. In 1880 he invented the modern seis mograph. In a sense this was a horizon tal pendulum, one end of which was fixed in bed rock. When the earth moved as a result of a quake, this motion would be recorded on a drum (either by a pen or by a quivering ray of light). Milne es tablished a chain of seismographs in Japan and elsewhere, marking the begin ning of modem seismology. When he returned to England (with his Japanese wife) he established a seis- mological station on the Isle of Wight. The velocity of earthquake vibrations through the earth’s body have told us al most all we know about the earth’s inte rior. In 1906 Milne attempted to deter mine the velocity of earthquake waves through the deep layers of the earth, with only limited success. Three years Download 17.33 Mb. Do'stlaringiz bilan baham: 
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