Biographical encyclopedia
Download 17.33 Mb. Pdf ko'rish
|
|
336 [503] HENRY
MELLONI [504] rent observed in the coil is, then, the combination of the original current and the induced current. This is called self induction, and the discovery is credited to Henry. Faraday discovered it indepen dently by 1834, but this time he was sec ond. A third man, Lenz [536], was also to discover this independently, and he was to go further in this connection than either Henry or Faraday. In 1831 Henry published a paper de scribing the electric motor. This, in a sense, is the opposite of the electric gen erator. In a generator, mechanical force turns a wheel and produces electricity. In a motor, electricity turns a wheel and produces mechanical force. The importance of the motor cannot be overemphasized. A motor can be made as large or as small as can be de sired. It can be run by electricity brought to it over a distance of many miles. It can be started in a moment and stopped in a moment. The supply of cheap, abundant elec tricity made possible (at least poten tially) by Faraday’s discovery of the generator would have been useless with out some means of putting it conve niently to work. It is Henry’s motor in vacuum cleaners, refrigerators, shavers, typewriters, and a hundred other electri cal appliances that puts it to work. Henry made an interesting contri bution to astronomy, too. He projected the image of the sun on a white screen in 1848 and, by sensitive measurements of heat, showed sunspots to be cooler than the rest of the sun. In 1846 Henry was elected first secre tary of the newly formed Smithsonian Institution and proved himself a first- class scientific administrator. He made the Smithsonian a clearing house of scientific knowledge and encouraged scientific communication on a worldwide scale. He was one of the founders of the National Academy of Sciences of the United States and one of the early presi dents of the body. He also encouraged the growth of new sciences within the United States. For in stance he was interested in meteorology and used the resources of the Smith sonian Institution to set up a system of obtaining weather reports from all over the nation, the telegraph’s first scientific use. The United States Weather Bureau was eventually founded upon the system he devised. During the American Civil War, Jo seph Henry headed the nation’s scientific mobilization, playing the role that, eight decades later, Bush [1139] was to play. He recommended the construction of ironclads and was eventually listened to. When Henry died, honor was his in full measure. His funeral was attended by high government officials, including Rutherford B. Hayes, then President of the United States. When the Interna tional Electrical Congress met in Chi cago in 1893 they agreed on having the unit of inductance named the henry. [504] MELLONI, Macedonio Italian physicist
gust 11, 1854 As was true later of Cannizzaro [668], Melloni, who was granted a profes sorship in physics at the University of Parma in 1824, took part in an un successful Italian revolution (in 1830) and had to leave the country for a time for France, reversing Cauchy’s [463] si multaneous exile. He returned when the furor died down and began research on infrared radiation in Naples where he was appointed director of the Cabinet of Arts and Trades. Herschel [321] had discovered infrared radiation a generation before, but tools were lacking with which to investigate it. In 1830, however, a thermopile was in vented—a series of strips of two different metals that produced electric currents when one end was heated. Very weak electric currents, and therefore very weak heating effects, could be de tected.
Melloni improved the thermopile and used it to trace the presence of infrared radiation. In 1846 he even measured the heating effect of moonlight from a spot high on Mount Vesuvius. He showed also that rock salt is transparent to infra red. He made lenses and prisms out of
[505] HENDERSON CLAPEYRON
rock salt and by 1850 showed that infra red light behaves just as ordinary light does as far as reflection, refraction, po larization, and interference are con cerned. Fresnel’s [455] mathematics ap plied to it, therefore, and infrared light is thus different from ordinary light only in its longer wavelength and in the fact (ir relevant to the physicist) that the human eye happens to be insensitive to it. The groundwork was thus laid for Maxwell’s [692] theoretical uncovering of an entire forest of radiation on either side of the visible spectrum far beyond any that had yet been detected. [505] HENDERSON, Thomas Scottish astronomer Born: Dundee, Angus, December 28, 1798 Died: Edinburgh, November 23, 1844
Henderson, the son of a tradesman, began as a lawyer, but he made a hobby of astronomy. As happens often, the hobby took over. In 1831 he was ap pointed director of the observatory at the Cape of Good Hope. This gave him the chance to observe the unusual star Alpha Centauri, which is the third brightest in the skies but is located so far south that it was never observed by Europeans until after the Age of Exploration began. Henderson succeeded in measuring its parallax, which turned out to be about three quarters of a second. This placed its distance at just over four light-years. It is therefore closer than 61 Cygni and, indeed, the system of stars represented by Alpha Centauri (it is made up of three stars altogether) is the closest known to this day. The closest of the three components, discovered in 1915, is a very small and feebly luminous star, called Proxima Centauri. Henderson actually completed his cal culations before Bessel [439] did, but his results were published only in January 1839, two months after Bessel’s an nouncement, and priority goes to the first to publish. Henderson was ap pointed the first astronomer royal of Scotland and ended his days as professor of astronomy at Edinburgh. [506] REICH, Ferdinand (rikhe) German mineralogist Born: Bernburg, Anhalt, Febru ary 19, 1799 Died: Freiberg, Saxony, April 27, 1882
Reich studied at Gottingen under Strohmeyer [411]. In 1823 he went to Paris and returned filled with enthusiasm for the metric system, which he intro duced into Saxony. He taught at the Freiberg School of Mines throughout his professional life. After the spectroscopic discovery of cesium and rubidium by Bunsen [565] and Kirchhoff [648] and of thallium by Crookes [695], Reich would have liked to go in for spectroscopic analysis him self. Here, however, he suffered under a peculiar handicap which he shared with Dalton [389]: He was color-blind. He therefore entrusted his assistant Richter [654] with the color part of the job. In 1863 Reich thought that a yellow precipitate he had obtained from a zinc ore might contain a new metal. Richter, examining it spectroscopically, found an indigo-colored line different from any produced by the known elements. This was proof of a new element, and it was named indium. [507] CLAPEYRON, Benoit Pierre Emile (clap-ih-rone') French engineer Born: Paris, February 26, 1799 Died: Paris, January 28, 1864 Clapeyron graduated from the ficole Polytechnique in 1818. He spent the decade of the 1820s in Russia teaching in St. Petersburg and returned to France following the July Revolution of 1830. He was particularly interested in steam engines, and he was the first to pay no table attention to the work of Carnot [497], Making use of Carnot’s principles, Clapeyron found an important rela tionship involving the heat of vapor ization of a fluid, its temperature, and the increase in volume involved in its va porization. This relationship, which he advanced in 1834, was related to what later came to be called the second law of
[508] ARGELANDER SCHÔNBEIN
thermodynamics. It was made more gen eral by Clausius [633], and it is usually known as the Clapeyron-Clausius equa tion. As an engineer, Clapeyron was notable for his work in designing and con structing locomotives and metal bridges. [508] ARGELANDER, Friedrich Wil helm August (ahriguh-lahn-der) German astronomer
Klaipeda, USSR), March 22, 1799 Died: Bonn, Rhenish Prussia, February 17, 1875 Argelander was born of a wealthy Finnish father and a German mother. Two Prussian princes lived for a while in the Argelander household when the Prussian royal family fled before the conquering Napoleon. The elder prince succeeded to the throne as Frederick William IV in 1840. Argelander was a student of Bessel [439] and obtained his Ph.D. at Königs berg in 1822. He was head of Finnish observatories, first at Turku then at Hel sinki from 1823 to 1836, then trans ferred to Bonn in Germany. At Bonn his personal friendship with Frederick Wil liam IV, made it possible for him to build a new observatory, something his predecessor had failed to obtain funds for. Argelander spent most of his profes sional life at Bonn locating stars, sac rificing some precision for the sake of quantity. From 1859 to 1862 he pub lished the giant Bonner Durchmusterung (Bonn Survey) in four volumes. It lo cated the positions of 457,848 stars, a far cry from the first star map of Hip parchus [50] with its fewer than a thou sand entries. It was the last star map to be compiled without the aid of photog raphy but was good enough to be re printed as late as 1950, by popular de mand. Argelander was the first to begin the detailed study of variable stars, of which only six were known when he started. He introduced the modem system of naming them, using letter prefixes begin ning with the letter R for rot (“red”) be cause so many variable stars were red. In 1863 he founded the Astro
ternational organization of astronomers. He also followed up Herschel’s [321] notion that the sun was moving and gained the first rough notion of its direc tion of motion. [509] LASSELL, William English astronomer Born: Bolton, Lancashire, June 18, 1799 Died: Maidenhead, Berkshire, October 5, 1880 Lassell’s life was something like that of a muted Herschel [321]. Lassell was a successful brewer (as Herschel had been a successful musician) who, like Her schel and Lord Rosse [513], took up as tronomy as a hobby, grinding his own lenses and adding valuable improvements in design that he devised himself. His first important discovery, in 1846, was that of Triton, Neptune’s large satel lite. Its name was suggested by Flam marion [756]. In 1848 he discovered an eighth satellite of Saturn (later named Hyperion), a discovery made simulta neously by G. P. Bond [660]. Finally, in 1851, he duplicated one of Herschel’s feats of half a century before by discovering two satellites of Uranus (making four altogether). The new satel lites Lassell named Ariel and Umbriel. He made these last discoveries in Malta, where he moved to escape the increas ingly smoky atmosphere of the indus trializing English midlands, which was making astronomical observations just about impossible. He returned to England in 1864. [510] SCHONBEIN, Christian Friedrich (shoin'bine) German-Swiss chemist Born: Metzingen, Württemberg, October 18, 1799 Died: Sauersberg, Baden, August 29, 1868 Schonbein, the son of poor parents, could not afford a formal education and 339 [510] SCHÖNBEIN TALBOT
was largely self-taught. He worked at a pharmaceutical factory and visited the universities of Tübingen and Erlangen when he could. He obtained some teach ing assignments, which included time in England, where he attended the lectures of Faraday [474], and in France, where he heard Gay-Lussac [420], Ampère [407], and Thénard [416]. He received an honorary Ph.D. at the University of Basel in 1828, joined its faculty and reached the position of full professor by 1835.
In 1840 he studied the peculiar odor that had been noticed for about half a century and more in the neighborhood of electrical equipment and that was par ticularly noticeable in Schönbein’s own poorly ventilated laboratory. Schönbein showed that he could produce the same odor by electrolyzing water or by allow ing phosphorus to oxidize. He traced that odor to a gas, which he named ozone, from the Greek word for “smell.” Andrews [580] proved it to be a high- energy form of oxygen, its molecule con taining three oxygen atoms where ordi nary oxygen molecules contain but two. Still more exciting things awaited Schönbein. The story goes that in 1845 he was toying with a mixture of nitric and sulfuric acids in the kitchen of his house. He was strictly forbidden to ex periment there, but his wife was absent. However, he spilled some of the acid. In a panic he seized the first thing at hand, his wife’s cotton apron, and sopped up the mixture, then hung it over the stove to dry before his wife came home and caught him. It dried all right and when it got dry enough, it went poof! and was gone. Whether Frau Schönbein had much to say on her return, history does not relate, but Schönbein at least was not too astonished or too browbeaten to experi ment further. He found that the acid mixture had added nitro groups (N 02) to the cellulose in the apron, forming ni trocellulose, and that this was excessively inflammable, burning without smoke or residue. Schönbein recognized the potential use of nitrocellulose in warfare and gave the substance a name that was the German equivalent of guncotton. Ordinary gunpowder was so smoky that it blackened the gunners, fouled the cannon, and raised a dark cloud that hid the battlefield. Here was something that might be used as a smokeless powder. Schonbein peddled the recipe to several governments, and guncotton factories sprang up. However, guncotton was a bit too unpredictable. It had the bad habit of exploding while still in the factory, which then “sprang up” in a more dras tic fashion. In 1847, for instance, a fac tory run in part by Schonbein himself blew up, killing twenty-one people. By the early 1860s guncotton seemed too hot to handle and the boom was over. However, methods were found to tame it and Dewar [759] and Abel [673] were soon to use it in the manufacture of cord ite, the first practical smokeless powder. The reign of gunpowder, which had begun in the time of Roger Bacon [99] six centuries earlier, was over, only to be replaced by something more efficiently destructive. Schonbein had a queer streak of con servatism in him. Almost to his death he refused to admit that Scheele [329] had been wrong in thinking chlorine a com pound, or that Davy [421] had been cor rect in proving it an element. He also firmly rejected the atomic theory. Even quite competent scientists can insist on being half a century out of date. [511] TALBOT, William Henry Fox English inventor
shire, February 11, 1800 Died: Lacock Abbey, Wiltshire, September 17, 1877 Talbot, the son of an army officer, ob tained his master’s at Cambridge in 1825, then, in 1833, entered Parliament. The political life was not for him, how ever. He retired the next year and began experimenting with photography as (un known to him) Daguerre [467] was doing across the Channel. By 1841 Talbot had patented the Tal-
[512] ROSS
ROSSE [513] botype. It was analogous to the da guerreotype but it introduced important improvements, including the production for the first time of a photographic nega tive, from which any number of positive prints could be made on paper. He re ceived the Rumford medal for this in 1842. In 1844 he published the first book illustrated with photographs. By 1851 he had developed methods by which the length of posing was drasti cally cut down, so that those who sat for photographs no longer had to be clamped in place to prevent motion. Talbot was also interested in archae ology and in the 1850s was one of the first to decipher the cuneiform tablets fished out of the ruins of Nineveh, capi tal of ancient Assyria. [512] ROSS, Sir James Clark Scottish explorer Born: London, England, April 15, 1800
Died: Aylesbury, Buckingham shire, England, April 3, 1862 Ross joined the Royal Navy in 1812. Over a period of twenty years, he ac companied his uncle on several expedi tions to the Canadian Arctic where, in those years, some practical waterway was searched for that would allow one to sail from the Atlantic to the Pacific (the Northwest Passage). On June 1, 1831, Ross sledged along the northern coast of North America and located the North Magnetic Pole. In 1839 Ross was given a command of his own and set out to explore the Ant arctic region. On January 1, 1841, he crossed the Antarctic Circle. He discov ered Mt. Erebus (named for one of his ships) the southernmost active volcano known. He sailed into the large oceanic inlet that cuts into Antarctica and that is now known as the Ross Sea in his honor. The southern portion of this sea is cov ered with a vast overhang of ice from the continental area behind and that is known as the Ross Ice Shelf. He was knighted in 1844. [513] ROSSE, William Parsons, 3d earl of Irish astronomer Born: York, England, June 17, 1800
Died: Monkstown, Cork, Ireland, October 31, 1867 An authentic member of the aristoc racy, William Parsons graduated from Oxford in 1822, sat in Parliament for a dozen years thereafter, resigning in 1834, and in 1841 succeeded to his fa ther’s earldom. In 1845 he was chosen to sit as an Irish representative in the House of Lords. Rosse’s love, indeed his obsession, was the construction of a giant reflecting tele scope. He taught himself to polish metal mirrors and, beginning in 1827, worked at it for years. He cut his eyeteeth on a 36-inch telescope and finally built his dream instrument, a 72-inch telescope, called “Leviathan,” in 1845. It is sup posed to have cost him £30,000. The work was particularly quixotic because weather conditions were so poor on his home estate in Ireland that it was rarely possible to use the clumsy instrument. (It took four men to run it.) Even so, Lord Rosse managed to make some im portant observations. For one thing, he was the first to make out the spiral shapes of cloudy objects that some three quarters of a century later were recognized as independent galaxies like our Milky Way, and mil lions of light-years away. He detected the first in 1845 and fourteen were dis covered by 1850. He also studied the ir regular foggy patch that Messier [305] had listed first in his catalogue of nebu lae. For some reason he thought it re sembled a crab, and in 1848 he gave it the name of Crab Nebula, which it has kept ever since. In that year he was elected to the Royal Society. Rosse was a humane man who consid ered his Irish tenants human beings. During the potato famine of 1846 he turned back a major portion of his rents to the farmers. Four thousand of his ten ants gathered twenty years later to mourn his death. Download 17.33 Mb. Do'stlaringiz bilan baham: 
|