Page:The New International Encyclopædia 1st ed. v. 11.djvu/854

* LAPLACE. 7 unable to give him any educational advan- tages, but, probably tluougli the generosity of friends, he was able to carry on his ^tudies in the College of Caen and the Military h<cliool at lieauniont. In the latter institution he was for a short time a teacher of iiialhcuiatics, but at the age of eighteen he resolved tii try hi^ fortune in Paris. Having secured the attention of U'Aleiu- bert (i^.v.), then in the lieiglit of liis power, he was, on the hitter's recuniniendatidn, made professor of niatheniaties in the Kcole Militaire. Scarcely twenty years of age, his remarkable power of mathematical analysis had already be- come manifest in his Hcclicrclics sur Ic calcul integral (1700-09). These researches were fol- lowed by a series of brilliant memoirs on the theory of probability, which immediately at- tracted the attention of the scicntilic world, and were the object of special commcndalion Ijy the Academy of Sciences. As a result uf their i)ub- lication, Laplace was in 1773 made an associate and in 1785 a member of this distinguished body. In 17S4 he succeeded IJezout as examiner in the Royal Artillery Corps, and in 17'.)4 was made professor of analysis at the Eeole Xormale. After the organization of the new Institute, he received, through the excellency of his style as shown in his tiyslcmc clii inoiidi. a ])lace among 'the forty' of the Academy in 1810, and in 1817 was maile its president. Laplace was not with- out political ambition, ami did not hesitate to resort to flattery to secure place. Najwleon made him Minister" of the Interior in 170!), but after six weeks he was comiH'lU'd to dismiss him with the epigrammatic remark that he carried the spirit of the infinitesimal into his administra- tion. He was recoiii])cnsed. liinvever. by a seat in the Senate, of which Ijody he later became the vice-])resident, and chancellor in 1803, In 1804 the Kmpcror also created him a count. His po- litical views conveniently shifting with the change of power, he received his reward from Louis XVIII. by being elevated to the peerage with the title of mar(|uis. He was a member (170.5), and a little later became president, of the Bureau of Longitudes: was president of the oonmiission for reorganizing the Kcole Polyt«H'h- iiiqiie: was a member of the commissiim to estab- lish the metric system, a grand officer of the Legion of Honor, and a member of most of the prominent learned societies of the world. La- place was indefatigable in his scientific labors and richly deserved the lumors which they brought to him. He has justly been called 'the Xewton of France.' 'the titanic gecmieter,' and 'the greatest mathematician of his age.' Self- sufficient in the presence of his fellows, he was humble in his contemplation of the great domain in which he labored, his humility showing itself in the dying words ascribed to liim: "What we know is little, what we do not know is immense," Laplace was celebrated chiefly for his labors in celestial mechanics, especially in relation to the lunar theory, the opposite inequalities of the motions of .Tupiter and .Saturn, the question of the tides, and the general problem of the stabil- ity of the solar system. The conciliation of the results of observations on the motions of .Tupiter and Saturn, to the Xewtonian theory, had baffled even Fouler and Lagrange, and it was the failure of such eminent predecessors that led him as a young man to study the subject. The results of his investigations were giveii when he was only ■2 LAPLACE. twenty-three years old, in a memoir read before the Academy of •Sciences, entitled tiiir Ivs svlu- lions purliculitres des equations different iellcs et sur les initjualites scculuires des planetcs. This was followed by a series of brilliant dis- coveries in the planetary theory- It was in con- nection with this extended investigation that Laplace discovered in 1780 the depenilciice of the moon's acceleration upon the secular changes in the eccentricity of the earth's orbit, the key- stone in the theory of the stability of the solar system. He also announced the laws of motion of the lirst three moons of .Jupiter, in a form since known as the 'Laws of Lajilaee': (1) The sum of the mean movement of the lirst satellite and of twice the third equals thri-e times that of the second: (2) the sum of the mean longitude of the lirst satellite and of double that of the second diminished by three times that of the third, eipials 1S0°. Laplace's most celebrated treatise is the Meranique celeste (5 vols., 1700- 1825; trans, by liowditch. 4 vols., Boston, 1820- 39). The aim of this work was to give a com- plete solution of the great mechanical problem of the solar system, and to bring the results of ob- sciTation into harmony with the Newtonian hy- pothesis. The work will stand as one of the world's greatest contributions to science. At the same time it cannot be denied that it has two .serious faults. In the first place. Laplace has justly been blamed for not recognizing the un- questionable discoveries of his predecessors and contemporaries, inferentially appropriating them as his own. The second blemish on the work is tlie fact that there are many serious omissions in the theory, covered by the frequently recurring expression, 'It is easy to see.' These two defects in the work were in jiart removed by the admir- able English translation mentioned above. La- place's h'.xponilion du systime dn monde (1796) was called by Arago the ilicanique eHeste, dis- robed of its analytic attire. The work is more popular and dear, and is especially valuable for its condensed but masterly resume' of the his- tory of astronomy to the close of the eighteenth century. In this work appeared the famous nebular hypothesis (see Cosmogony), an hy- pothesis so foreign to Laplace's habit of mathe- matical treatment as to lead him to the apolo- getic statement that it was suggested "with the mistrust which should inspire everything that is not a result of observation or calculation;" but to it he frequently alludes as highly probable. In physics. Laplace joined with Lavoisier in important experiments (1782-84) on the specific heats of bodies, and cimtributed in a noteworthy manner to the theories of capillary action, of electricity, and of the equilibrium of a rotating fluid mass. His investigation of the discrep- ancy between the theoretical and observed ve- locity of sound led him to take into mathemati- cal account various secondary factors by which the velocity of sound may be influenced. 'La- place's coefficients.' also called spherical func- tions and spherical harmonies, already known to Legendie. were first given in their general form by Laplace, in his Throrie des nttrnctions des xphrniides el de la fifiure des planctes (1782). In pure mathematics. Laplace made his greatest reputation in the theory of probabilities (q.v.). This doctrine, already cre.ited by Pascal and Fer- niat. and hroiicht to a high degree of perfection by .Jakob Bernoulli (q.v.), was investigated by