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to Paris, where he attended courses on chemistry andbotany; taught a course of his own on chemistry,experimented two afternoons weekly with C . J . andE. F. Geoffroy ; and made the acquaintance of all theleading scientists. In 1719 lie returned to Berlin byway of Rome .

Upon his return, Neumann as court apothecarytook on the demanding job of running one of Europe'sbusiest pharmacies. Nevertheless, he managed to findtime for other activities . In 1721 he began activemembership in Berlin's Society of Sciences, and in1724 he became a member of the chief Prussianmedical board and began teaching in the new Medical-Surgical College as professor of practical (experi-mental) chemistry . He remained in all these positionsuntil his death in 1737 at the age of fifty-four .

In the mid-1720's, after more than a decade ofserious work in chemistry, Neumann began his shortyet prolific career as an author with a series of articlesin the Philosophical Transactions . After his death hiscollected lectures appeared in two German versionsand, partially at least, in English, Dutch, and Frenchtranslations .

Though Neumann was not a highly original chemist,he did influence the development of chemistry in avariety of ways . First, during his Wanderjahre, heconveyed knowledge of German techniques andtheories to chemists in London and Paris. Second, asmaster pharmacist and as professor, he gave the youngMarggraf his initial instruction in chemistry . It maywell have been Neumann's exhortations that inspiredMarggraf to develop "wet" analysis . Third, as anauthor he contributed significantly to the establish-ment of Stahlian chemistry, especially in Germany butalso abroad . Like Stahl's other main disciples-Pott,Henckel, and Juncker-Neumann distinguished clearlybetween pure and applied chemistry and insisted thatthe chemical approach to nature was vastly superior tothe mechanical philosophy . He envisioned many levelsof chemical aggregation and invoked the phlogistontheory to explain combustion and calcination-reduction . Unlike Stahl's other main disciples,Neumann concentrated on pharmaceutical chemistry,thereby reaching and inspiring a generation ofpharmacists which included Scheele and Klaproth .

BIBLIOGRAPHY

I . ORIGINAL WORKS . See Praelectiones chemicae seachenna medico-plrarmaceutica experbnentalis & rationalis,oiler griindlicher Unterricht der C/ie,nie . . . (Berlin, 1740),edited on the basis of student notes by J . C. Zimmermannwith the assistance of J . H. Pott, with portrait . Zimnler-mann republished this ed . with minor changes under his

26

NEUMANN

own name in 1755 . Neumann's nephew C . H. Kessel putout a different ed . which was based on Neumann's ownnotes, Ch vniae medicae dogmatico-experimentalis . . . oilerder griincflieheir uncl hit Experimenter erwiesenen Medici-nischen Ch wrie . . ., 4 vols. (Ztillichau, 1749-1755 ; partialreprint, 1755-1756). W. Lewis' English ed . appeared in1759 and 1773, the Dutch ed . i n 1766, and Roux's Frenched . i n 1781 . A complete bibliography of Neumann's workswhich mentions many reviews appears in Exner's biog-raphy, cited below, and an annotated partial bibliographyin J. R. Partington, A History of Cherristra', II (London-New York, 1961), 702-706 .

11 . SECONDARY LITERATURE . The best biography isAlfred Exner, Der Hofapotheker Caspar Neumann (1683-1737) (Berlin, 1938) . Exner begins with an annotatedtrans . of A . P . Queitsch's Latin biography (1737) and then,relying heavily on Kessel's ed . of the lectures, he assessesNeumann's role in chemistry and pharmacy . Some addi-tional materials are in Herbert Lehmann, Das Collegiummedico-chirrrgicam in Berlin als LehrWitte der Botanik arrdder Pharmazie (Berlin, 1936) .

KARL HUFBAUER

NEUMANN, FRANZ ERNST (b. Joachimsthal,Germany

[now

Jachymov,

Czechoslovakia],II September 1798; d. Konigsberg, Germany [nowKaliningrad, R.S.F.S .R .], 23 May 1895), Mineralogy,physics, mathematics.

Neumann extended the Dulong-Petit law-that thespecific heats of the elements vary inversely as theiratomic weights-to include compounds having similarchemical constitutions . His work in optics contributedto the establishment of the dynamical theory of light,and he formulated mathematically the laws of induc-tion of electric currents. He also aided in developingthe theory of spherical harmonics. Neumann was ahighly influential teacher ; many of his students becameoutstanding scientists, and he inaugurated themathematical science seminar at German universities .Neumann's mother was a divorced countess whose

family prevented her marrying his father, a farmerwho later became an estate agent, because he was notof noble birth . Neumann was therefore raised byhis paternal grandparents . He attended the BerlinGymnasium, where he displayed an early talent formathematics . His education was interrupted in 1814,when he became a volunteer in the Prussian army tofight against Napoleon . He was seriously wounded on16 June 1815 at the battle of Ligny, the prelude toWaterloo . After recovering in a Dusseldorf hospital,he rejoined his company and was mustered out of thearmy in February 1816.

Because his father had lost all of his resources ina fire, Neumann pursued his education under severe

NEUMANN

financial difficulties . He completed his studies atthe Gymnasium and in 1817 entered the Universityof Berlin, studying theology in accordance with hisfather's wishes . In April 1818 he left Berlin for Jena,where he began his scientific studies and was particu-larly attracted to mineralogy . In 1819 Neumannreturned to Berlin to study mineralogy and crystallo-graphy under Christian S . Weiss, who became hisclose friend as well as his mentor. Weiss made thefinancial arrangements for Neumann to take athree-month geological field trip in Silesia during thesummer of 1820, and Neumann was planning othertrips for 1822 and 1823 when his father died . There-after Neumann and his mother became very close ;his concern for her health and financial independencecaused him to leave the university during 1822-1823and manage her farm . Nevertheless, in 1823 hepublished his first work, Beitrdge zur Kristallonomie,which was highly regarded in Germany ; and onWeiss's recommendation he was appointed curatorof the mineral cabinet at the University of Berlin inNovember 1823 .Neumann received the doctorate at Berlin in

November 1825 ; and in May 1826, together withJacobi and Dove, he became a Prit atdozent at theUniversity of Konigsberg . Dove and Neumann weredestined to assume the physics and mineralogycourses, respectively, of Karl G . Hagen, who hadbeen teaching botany, zoology, mineralogy, chemistry,and physics. In 1828 Neumann was advanced to therank of lecturer, and in 1829 he was named professorof mineralogy and physics . He married Hagen'sdaughter, Luise Florentine, in 1830; they had fivechildren before her death in 1838. He marriedWilhelmina Hagen, her first cousin, in 1843 .

Neumann's early scientific works, published be-tween 1823 and 1830, concerned crystallography ;in these he introduced the method of sphericalprojection and extended Weiss's work on the law ofzones (law of rational intercepts). At Konigsberg,however, he was influenced by Bessel, Dove, andJacobi ; and he began to concentrate on mathematicalphysics . His first two important papers were publishedin Poggendorff's Annalen der Physik and Chemie(23 [1831], 1-39 and 40-53); the first was entitled"Untersuchung uber die specifische Warme derMineralien" and the second "Bestimmung derspecifischen Warme des Wassers in der Nahe desSiedpuncktes gegen Wasser von niedriger Tempe-ratur ." In the first article Neumann investigated thespecific heats of minerals and extended the Dulong-Petit law to include compound substances havingsimilar chemical constitutions . He arrived at what hasbeen termed Neumann's law, that the molecular heat

27

NEUMANN

of a compound is equal to the sum of the atomicheats of its constituents . In the second paper Neumannconsidered the specific heat of water . In earlierinvestigations physicists had noticed that when equalquantities of hot and cold water are mixed thetemperature of the mixture is lower than thearithmetic mean of the temperatures of the originalquantities . This result was generally interpreted asbeing due to a progressive decrease in the specific heatof water from the point of fusion to that of vaporiza-tion, a conclusion that appears to be validated by anumber of experiments . Neumann disclosed errorsin these experiments and concluded instead that thespecific heat of water increases as its temperatureincreases . He failed to determine, however, that anincrease occurs over only a portion of the temperaturerange from fusion to vaporization .In 1832 Neumann published another important

paper, again in Poggendorff's Annalen, "Theorie derdoppelten Strahlenbrechnung abgeleitet aus derGleichungen der Mechanik ." Many physicists andmathematicians of the period were concerned withdetermining the conditions under which waves arepropagated in ordinary elastic bodies so that theymight develop a model which could serve as theoptical medium ; that is, they wished to evolve anelastic-solid theory of the ether in order to promotethe undulatory theory of light . In his article Neumannreported obtaining a wave surface identical with thatdetermined earlier by Augustin Cauchy, and hesucceeded in deducing laws of double refractionagreeing with those of Fresnel except in the case ofbiaxial crystals .

Neumann encountered difficulty in explaining thepassage of light from one medium to another . Heattempted to overcome this obstacle in an articleentitled "Theoretische Untersuchungen der Gesetze,nach welchen das Licht an der Grenze zweier vollkom-men durchsichtigen Medien reflectirt and gebrochenwird," published in Abhandlungen der PreussischenAkademie der Wissenschaften, mathematische Klasse([1835], 1-160). In this paper Neumann raised thequestion of the mathematical expression of theconditions which must hold at the surface separatingthe two crystalline media, and he adopted the viewthat the density of the ether must be identical in allmedia.Neumann and his contemporary Wilhehn Weber

were the founders of the electrodynamic school inGermany, which later included, among others,Riemann, Betti, Carl Neumann, and Lorenz . Theinvestigations and analyses of this group were guidedby the assumption, held originally by Ampere, thatelectromagnetic phenomena resulted from

NEUMANN

action at a distance rather than through the mediationof a field . Neumann's major contributions werecontained in two papers published in 1845 and 1848,in which he established mathematically the laws ofinduction of electric currents . The papers, transmittedto the Berlin Academy, were entitled "AllgemeineGesetze der inducirten elektrischen Strome" and"Ober ein allgemeines Princip der mathematischenTheorie inducirter elektrischer Strome ."

As a starting point Neumann took the proposition,formulated in 1834 by F . E. Lenz after Faraday'sdiscovery of induction, that the current induced in aconductor moving in the vicinity of a galvanic currentor a magnet will flow in the direction that tends tooppose the motion . In his mathematical analysisNeumann arrived at the formula E • Ds = -cc C • Ds,where Ds is an element of the moving conductor,E Ds is the elementary induced electromotive force,v is the velocity of the motion, C • Ds is the componentof the inducing current, and E is a constant coefficient .With this formula Neumann was able to calculate theinduced current in numerous particular instances . Atpresent a common formulation is E _ - dN/dt, whereE is the electromotive force generated in the circuitthrough which the number of magnetic lines of forceis changing at the rate of dN/dt .Continuing his analysis Neumann noticed a way in

which the treatment of currents induced in closedcircuits moving in what is now termed a magneticfield might be generalized . He saw that the inducedcurrent depends only on the alteration, caused by themotion, in the value of a particular function . Con-sidering Ampere's equations for a closed circuit,Neumann arrived at what is known as the mutualpotential of two circuits, that is, the amount ofmechanical work that must be performed against theelectromagnetic forces in order to separate the twocircuits to an infinite distance apart, when the currentstrengths are maintained unchanged . In modernnotation the potential function, Vii', is written :

ds ds'171' _ -11

JJ r

ds • ds' is the scalar product of the two vectors dsand ds', and r their distance apart. If a fixed elementds' is taken and integrated with respect to ds, thevector potential of the first circuit at the point occupiedby ds is obtained . Maxwell arrived at the concept ofvector potentials by another method and interpretedthem as analytical measures of Faraday's electrotonicstate .

According to his contemporaries, only a small por-tion of Neumann's original scientific work waspublished . But lie was an extremely effective teacher,

28

NEUMANN

and he made known many of his discoveries in heat,optics, electrodynamics, and capillarity during hislectures, thinking that priority of discovery extendedequally to lectures and publications . Thus he madenumerous contributions to the theory of heat withoutreceiving credit ; on occasion he thought about raisingquestions concerning priority but never did .

In 1833, with Jacobi, Neumann inaugurated theGerman tnathematisch-physikalische seminar, em-ploying such sessions to supplement his lectures andto introduce his students to research methodology .Gustav Kirchhoff attended these seminars from 1843to 1846; his first papers on the distribution of electricalconductors, and H. Weld's development of thephotometer and polarimeter, were among the directresults of Neumann's seminars . Neumann pleadedcontinually for the construction of a physics laboratoryat Konigsberg, but his hopes were thwarted during histenure as professor ; a physics institute was notcompleted at Konigsberg until 1885 . In 1847, however,the inheritance from the estate of the parents of hissecond wife enabled Neumann to build a physicslaboratory next to his home, the facilities of whichhe shared with his students . He retired as professorin 1873, although he continued his seminar for thenext three years . He maintained his good health bymaking frequent walking tours throughout Germanyand Austria, and he was still climbing mountains atthe age of eighty .Throughout his life Neumann was an ardent

Prussian patriot . He aided in keeping peace inKonigsberg during the uprisings of 1848. He pleadedcontinually for the unification bf Germany under theleadership of Prussia, and in the early 1860's he madenumerous political speeches supporting Bismarck andthe war against Austria . At the fiftieth anniversary ofhis doctorate in 1876, he was congratulated by thecrown prince, later Wilhehn I I ; and he received honorsfrom Bismarck in 1892 as a veteran of the campaignof 1815. Neumann was a corresponding member ofevery major European academy of science ; he receivedthe Copley Medal of the Royal Society in 1887 .

BIBLIOGRAPHY

I . ORIGINAL WORKS . Three of Neumann's most im-portant works were published in Ostwalds Klassiker derExakten Wissenschaften : Die mathernatischen Gesetze derinducirten elektrischen Strome, no. 10 (Leipzig, 1889) ; Cbercin allgelncines Princip der nlathematischen Theorieinducirter elektrischer Strdlne, no. 36 (Leipzig, 1892) ; andTheorie der doppelten Strahlenbrechnung, no. 76 (Leipzig,1896) . Other books are Bcitrdge zur Kristallononrie(Berlin-Posen, 1823) ; Cher den Einfluss der Krystallfldc•hen

NEUMAYR

bei der Reflexion des Lichtes and fiber die Intensitdt desgewohnlichen and ungewohnlichen Strahls (Berlin, 1837) ;and Beitrige zur Theorie der Kugelfunktionen (Leipzig,1878). Some of his lectures were published in Vorlesungfiber mathematischen Physik gehalten an der UniversitdtKonigsberg von Franz Neumann, Carl Neumann, C . Pape,Carl Vondermuhll, and E . Dorn, eds ., 5 vols . (Leipzig,1881-1887) . His collected works were published as FranzNeuinanns Gesammelte Werke, 3 vols . (Leipzig, 1906-1928) .

11 . SECONDARY LITERATURE . See C. Volt, "Nekrolog aufFranz Ernst Neumann," in Sitzungsberichte der AkademieMiinchen, 26 (1896), 338-343 ; Luise Neumann, FranzNeumann: Erinnerungsbldtter (Tubingen-Leipzig, 1904) ;W. Voigt, "Gedachtnissrede auf Franz Neumann," inFranz Neuananns Gesammelte Werke, I (Leipzig, 1906),1-19; and Paul Volkmann, Franz Neumann . . . denAndenken an dem Altmeister der mathematischen Physikgewidmete Bliitter (Leipzig, 1896) .

See also James Clerk Maxwell, A Treatise on Electricityand Magnetism, 3rd ed . (Oxford, 1891), art . 542 ; and SirEdmund Whittaker, A History of the Theories of Aetherand Electricity, I (London, 1951), 137-138, 166-167,198-200 .

JOHN G. BURKE

NEUMAYR, MELCHIOR (b. Munich, Germany,24 October 1845 ; d. Vienna, Austria, 29 January 1890),paleontology, geology .

Neumayr was the son of Max von Neumayr, aBavarian government minister . He attended secondaryschools in Stuttgart and in Munich, where he alsostudied law . Under the influence of Oppel, lie soonturned to paleontology and geology and received thedoctorate in Munich in 1867 . The following year hemoved to Vienna and joined the Imperial AustrianGeological Survey . In 1872 he became Privatdozent inpaleontology and stratigraphy at the University ofHeidelberg. He returned to Vienna in 1873 to fill thenew professorship of paleontology that had beencreated for him at the university and held this postuntil his death from a heart ailment . On 2 April 1879he married Paula Suess, the daughter of his colleagueEduard Suess ; they had three daughters .

Neumayr's first scientific work was his geologicalmapping of southern Germany, the Carpathians, andthe eastern Alps. His subsequent paleontological andstratigraphical investigations of the Jurassic period(1870-1871, 1874) soon established him as an expert onthis period and its fauna. In studies of the UpperTertiary freshwater mollusks of Yugoslavia, work thathe began in 1869, he showed the gradual transforma-tion of the shell morphology in the various horizons .A follower of Darwin from his student days, Neumayr

29

NEUMAYR

was the first to give a concise demonstration of theDarwinian theory of variation and evolution of speciesin invertebrate fossils (1875) .

Neumayr's geological and paleontological investiga-tions in Greece and in the Aegean Islands (1874-1876)made fundamental contributions to the knowledge ofthe geological structure of this region . In the UpperTertiary of the island of Cos he found an even finerexample of the evolution of freshwater snails (1880) .A result of his studies in the Aegean was the firstgeological history of the eastern Mediterranean, inwhich methodological principles of paleogeographywere demonstrated (1882) .

Continuing his studies of the ammonites, Neumayrthen turned his attention to the Cretaceous species,dividing them into new genera, as Suess had done forthe Triassic and Jurassic forms . He clarified the rela-tionships of the straightened forms to the parent curledgenera and discussed the Cretaceous ammonites inrelation to those of the Jurassic and Triassic periods .By extending his paleobiogeographic research to theJurassic and Cretaceous periods he created the founda-tions of the present conceptions of the faunal regionsin the Jurassic seas (1885) . He also studied climaticdifferentiation during the Jurassic and Cretaceousperiods (1883) .

During his last years, Neumayr was occupied withwriting comprehensive surveys and in his Erdgeschichtehe produced a popular synthesis with strictly scientificmethods. His unfinished Die Stdmine des Tluerreicheswas Darwinian in approach and showed the closerelationship between zoology and paleontology . Hethereby raised paleontology-previously consideredsimply a study of index fossils-to the level of a basicbiological science .

BIBLIOGRAPHY

I. ORIGINAL WORKS . Neumayr's writings include "Jura-studien," in Jahrbuch der Geologischen Bundesanstalt, 20(1870), 549-558 ; 21 (1871), 297-379; "Die Fauna derSchichten mit Aspidoceras acanthicum," in Abhandhutgender Geologischen Bundesanstalt, 5 (1874), 141-257 ; "DieCongerien- and Paludinenschichten Slavoniens and derenFauna," ibid., 7, no. 3 (1875), written with C . M . Paul ;"Uber den geologischen Bau der Insel Kos anddie Gliederung der jungtertiaren Binnenablagerungen imArchipel," in Denkschriften der Akade,nie der Wissen-schaften, 40 (1880), 213-240 ; Zur Geschichte des ostlichenMittehneerbeckens (Berlin, 1882) ; "Ueber klimatischeZonen wahrend der Kreide- and Jurazeit," in Denk-schriften der Akadeinic der Wissenschaften, 47 (1883),277-310; "Die geographische Verbreitung der Jura-formation," ibid., 50 (1885), 57-145 ; Erdgeschichte,