GAUSS

gauss, karl friedrich (1777-1855), german mathematician, was born of humble parents at brunswick on the 30th of april 1777, and was indebted for a liberal education to the notice which his talents procured him from the reigning duke. his name became widely known by the publication, in his twenty-fifth year (1801), of the _disquisitiones arithmeticae_. in 1807 he was appointed director of the gottingen observatory, an office which he retained to his death: it is said that he never slept away from under the roof of his observatory, except on one occasion, when he accepted an invitation from baron von humboldt to attend a meeting of natural philosophers at berlin. in 1809 he published at hamburg his _theoria motus corporum coelestium_, a work which gave a powerful impulse to the true methods of astronomical observation; and his astronomical workings, observations, calculations of orbits of planets and comets, &c., are very numerous and valuable. he continued his labours in the theory of numbers and other analytical subjects, and communicated a long series of memoirs to the royal society of sciences (_konigliche gesellschaft der wissenschaften_) at gottingen. his first memoir on the theory of magnetism, _intensitas vis magneticae terrestris ad mensuram absolutam revocata_, was published in 1833, and he shortly afterwards proceeded, in conjunction with wilhelm weber, to invent new apparatus for observing the earth's magnetism and its changes; the instruments devised by them were the declination instrument and the bifilar magnetometer. with weber's assistance he erected in 1833 at gottingen a magnetic observatory free from iron (as humboldt and f.j.d. arago had previously done on a smaller scale), where he made magnetic observations, and from this same observatory he sent telegraphic signals to the neighbouring town, thus showing the practicability of an electromagnetic telegraph. he further instituted an association (_magnetischer verein_), composed at first almost entirely of germans, whose continuous observations on fixed term-days extended from holland to sicily. the volumes of their publication, _resultate am den beobachtungen des magnetischen vereins_, extend from 1836 to 1839; and in those for 1838 and 1839 are contained the two important memoirs by gauss, _allgemeine theorie des erdmagnetismus, and the allgemeine lehrsatze_--on the theory of forces attracting according to the inverse square of the distance. the instruments and methods thus due to him are substantially those employed in the magnetic observatories throughout the world. he co-operated in the danish and hanoverian measurements of an arc and trigonometrical operations (1821-1848), and wrote (1843, 1846) the two memoirs _uber gegenstande der hoheren geodasie_. connected with observations in general we have (1812-1826) the memoir _theoria combinationis observationum erroribus minimis obnoxia_, with a second part and a supplement. another memoir of applied mathematics is the _dioptrische untersuchungen_ (1840). gauss was well versed in general literature and the chief languages of modern europe, and was a member of nearly all the leading scientific societies in europe. he died at gottingen on the 23rd of february 1855. the centenary of his birth was celebrated (1877) at his native place, brunswick. gauss's collected works were published by the royal society of gottingen, in 7 vols. 4to (gott., 1863-1871), edited by e.j. schering--(1) the _disquisitiones arithmeticae_, (2) _theory of numbers_, (3) _analysis_, (4) _geometry and method of least squares_, (5) _mathematical physics_, (6) _astronomy_, and (7) the _theoria motus corporum coelestium_. additional volumes have since been published, _fundamente der geometrie usw_. (1900), and _geodatische nachtrage zu band iv_. (1903). they include, besides his various works and memoirs, notices by him of many of these, and of works of other authors in the _gottingen gelehrte anzeigen_, and a considerable amount of previously unpublished matter, _nachlass_. of the memoirs in pure mathematics, comprised for the most part in vols, ii., iii. and iv. (but to these must be added those on _attractions_ in vol. v.), it may be safely said there is not one which has not signally contributed to the progress of the branch of mathematics to which it belongs, or which would not require to be carefully analysed in a history of the subject. running through these volumes in order, we have in the second the memoir, _summatio quarundam serierum singularium_, the memoirs on the theory of biquadratic residues, in which the notion of complex numbers of the form a + _bi_ was first introduced into the theory of numbers; and included in the _nachlass_ are some valuable tables. that for the conversion of a fraction into decimals (giving the complete period for all the prime numbers up to 997) is a specimen of the extraordinary love which gauss had for long arithmetical calculations; and the amount of work gone through in the construction of the table of the number of the classes of binary quadratic forms must also have been tremendous. in vol. iii. we have memoirs relating to the proof of the theorem that every numerical equation has a real or imaginary root, the memoir on the _hypergeometric series_, that on _interpolation_, and the memoir _determinatio attractionis_--in which a planetary mass is considered as distributed over its orbit according to the time in which each portion of the orbit is described, and the question (having an implied reference to the theory of secular perturbations) is to find the attraction of such a ring. in the solution the value of an elliptic function is found by means of the _arithmetico-geometrical mean_. the _nachlass_ contains further researches on this subject, and also researches (unfortunately very fragmentary) on the lemniscate-function, &., showing that gauss was, even before 1800, in possession of many of the discoveries which have made the names of n.h. abel and k.g.j. jacobi illustrious. in vol. iv. we have the memoir _allgemeine auflosung_, on the graphical representation of one surface upon another, and the _disquisitiones generales circa superficies curvas_. (an account of the treatment of surfaces which he originated in this paper will be found in the article surface.) and in vol. v. we have a memoir _on the attraction of homogeneous ellipsoids_, and the already mentioned memoir _allgemeine lehrsatze_, on the theory of forces attracting according to the inverse square of the distance. (a. ca.)