works represent applications of the results of his theory of equations, that is, the rule of tangents and extreme values.

Hudde was also interested in physics and astronomy. He spent much time with the astronomer Ismael Boulliau and reported his comet observations to Huygens in 1665. In 1663 he produced microscopes with spherical lenses; in 1665 he worked with Spinoza on the construction of telescope lenses. That he also had assembled a small dioptrica is seen from his correspondence with Spinoza. In 1671 he sent to Huygens mortality tables for the calculation of life annuities. During the next two years Hudde was charged by the city of Amsterdam with appraising DeWitt's formulas for the calculation of life annuities. Perhaps the most gifted of Schooten's students, Hudde was also the most strongly influenced by him. At the time of Schooten's death in 1660, Hudde felt that he commanded a comprehensive view of the basic contemporary mathematical problems. Like Descartes he held as meaningful only such mathematical problems as could be handled through algebraic equations. After 1663 he pursued mathematics only as an avocation apart from-for himmore important civic activities.

His contemporaries saw him as a mathematician of great ability. Leibniz wrote, even as late as 1697, that one could expect a solution to the difficult problem of the brachistochrone only from L'Hospital, Newton, the Bernoullis, and Hudde "had he not ceased such investigations long ago."

BIBLIOGRAPHY

I. ORIGINAL WORKS. Frans van Schooten's Exercitationum mathematicarum libri quinque (Leiden, 1657) contains three essays by Hudde; see Schooten's ed. of Descartes's Géométrie, Geometria Renati Cartesii, I (Amsterdam, 1659), for Hudde's De reductione aequationum and De maximis et minimis. Hudde's correspondence with Huygens is in the latter's Oeuvres complètes, 22 vols. (The Hague, 1888-1950).

II. SECONDARY LITERATURE. On Hudde and his contributions, see Karlheinz Haas, "Die mathematischen Arbeiten von Johann Hudde," in Centaurus, 4 (1956), 235-284-the app. contains an extensive bibliography; Joseph E. Hofmann, Geschichte der Mathematik, pt. 2, (Berlin, 1957), pp. 45-46, 54, 74; and P. C. Molhuysen and P. J. Blok, eds., Nieuw Neederlandsch biografisch Woordenboek (Leiden, 1911-1937).

KARLHEINZ HAAS

HUDSON, CLAUDE SILBERT (b. Atlanta, Georgia, 26 January, 1881; d. Washington, D. C., 27 December 1952), chemistry.

Hudson's career was spent almost entirely in governmental laboratories in Washington, where he trained many followers in the chemistry of the sugars. He was born of early American stock, spent his youth in Mobile, Alabama, and received the B.S. (1901), Ph.D. (physics, 1907), and Hon. D.Sc. (1947) degrees from Princeton University. His early interest was in physical chemistry, which he studied with Nernst at Göttingen and van't Hoff at Berlin. From 1928 to 1951 Hudson served in the National Institutes of Health.

Hudson and his many associates developed the stereochemistry of the anomeric sugar centers, beginning with his rules of isorotation, useful for allocation of anomeric form when proper substituents are present. This development was followed by a rule establishing the point of ring closure in aldonolactones. Hudson demonstrated that enzymic reactions follow the laws of mass action and he showed that the D-fructose unit of sucrose possesses an unusual form. He established the equation expressing the acid-base dependency of the rate of D-glucose mutarotation and from this calculated an accepted value for the ionic dissociation of water. He correlated anomeric configurations through periodate oxidation, calculated rotatory powers of unisolated anomers by the principle of maximum solubility, and synthesized the (1-4)-B-D-linked disaccharides lactose and cellobiose. Hudson prepared many sugars and their acetates in pure anomeric forms and with the D-galactose pentaacetates, established that a sugar could exist in more than one ring form.

Hudson received many awards and he was elected to membership in distinguished scientific bodies in the United States and abroad. In his relaxed moments he was a noted bon vivant and raconteur, but when at work he was an exacting person, holding himself and his associates to high standards.

BIBLIOGRAPHY

The obituary by Lyndon F. Small and Melville L. Wolfrom in Biographical Memoirs. National Academy of Sciences, 32 (1958), 181-220, contains a bibliography of Hudson's publications, including posthumous works, from 1902-1955.

MELVILLE L. WOLFROM

HUDSON, WILLIAM (b. Kendal, Westmorland, England, 1733; d. London, England, 23 May 1793), botany.

Hudson was born and raised in Kendal, where his father kept the White Lion Inn. He was educated in

the Kendal Grammar School and, on completion of his studies, was apprenticed to an apothecary on Panton Street, Haymarket, London.

Hudson proved an apt student. During his year apprenticeship he won the Apothecaries' Company's prize for botany. Between 1757 and 1758 his horizons were widened when, as resident sublibrarian of the British Museum, he studied the Sloane herbarium. Hudson was subsequently encouraged by Benjamin Stillingfleet, who introduced him to the writings of Linnaeus, to restate John Ray's Synopsis methodica stirpium Britannicarum in terms of the Linnean system. Thus, in 1762 he published Flora Anglica, which incorporated the work of other naturalists with a rearrangement of the Synopsis. Hudson's clear and concise language, accuracy in determining plant locations, accounts of medicinal values of the plants, and addition of valuable synonyms were very useful and popular. Flora Anglica quickly replaced Ray's Synopsis as the standard English flora and won most English naturalists over to the Linnean sexual system. In 1778 Hudson published a second, enlarged edition of his work; a reprint of the second edition appeared in 1798.

Hudson became a fellow of the Royal Society in 1761 and of the Linnean Society in 1791. From 1765 to 1771 he was director and botanical demonstrator for the Apothecaries' Garden. Growing fiscal difficulties at the garden forced Philip Miller to resign in 1770, and in 1771 Hudson tendered his own resignation as well.

Hudson's interests also included insects and mollusks, and he planned to write a Fauna Britannica. Unfortunately a fire in 1783 destroyed his collections, papers, and Panton Street home. Although Hudson continued his interest in natural history, his slender financial resources were not adequate to replace the loss.

Hudson never married. When his master died, Hudson took over his apothecary practice and lodged with his widow; on her death, he was joined by her daughter and son-in-law. When the residence was destroyed, they moved to a house on Jermyn Street where, after suffering for several years from what James Edward Smith describes as ulcerated lungs, and a series of paralytic strokes, Hudson died. He was interred in St. James's Church, and the remains of his collections were given to the Apothecaries' Garden in Chelsea.

BIBLIOGRAPHY

I. ORIGINAL WORKS. Hudson's only published book is Flora Anglica (London, 1762; 2nd, enl. ed., 1778; 2nd ed.

repr. 1798). From 1768 to 1770 he published an annual "Catalogue of the Fifty Plants From Chelsea Garden, Presented to the Royal Society by the... Company of the Apothecaries" in Philosophical Transactions of the Royal Society, 58, 59, and 60.

II. SECONDARY LITERATURE. The most useful sources of information are articles by James Edward Smith in Abraham Rees, Cyclopaedia, XVIII, and G. S. Boulger in Dictionary of National Biography, new ed., X, 155. J. Reynolds Green, A History of Botany in the United Kingdom (London, 1914), pp. 271-273, sheds valuable light on the importance of Hudson's work with the Chelsea Apothecaries' Garden. Richard Pulteney, Historical and Biographical Sketches of the Progress of Botany in England (London, 1790), pp. 351-352, provides supplementary information about Hudson's contributions to the acceptance of Linnean taxonomy in England. Accounts of Hudson's death appear in Annual Register: Chronicle (1793), pp. 25-26; Gentleman's Magazine, 63 (May 1793), 485; and John Nichols, Literary Anecdotes of the Eighteenth Century, IX (London, 1815), 565-566.

For a bibliography about Hudson, see James Britten and G. S. Boulger, A Biographical Index of British and Irish Botanists, 2nd ed., rev. by A. R. Rendle (London, 1931), pp. 157-158, the most recent and helpful source. The Dictionary of National Biography (see above) is also quite valuable.

ROY A. RAUSCHENBERG

HUFNAGEL, LEON (b. Warsaw, Poland, 1893; d. Berlin, Germany, 19 February 1933), astronomy.

Hufnagel entered the faculty of mathematics and physics of Warsaw University in 1911. After receiving the Ph.D. at Vienna in 1919, he returned to Poland, serving as an assistant at the Free University, Warsaw, in 1921-1926. In the latter year he left Poland for Sweden, where he worked at Lund Observatory in 1926-1928. For the next two years he was Rockefeller traveling fellow at the Mt. Wilson, Lick, and Harvard College observatories. From 1930 he worked at the Astronomisches Recheninstitut, Berlin-Dahlem, and the astrophysical observatory, Potsdam.

Hufnagel's first scientific papers were in celestial mechanics. In 1919 he determined the orbit of the great September comet (1882 II), and with J. Krassowski he calculated the perturbations of the asteroid (43) Ariadne in 1925. After 1925 his major scientific work concerned stellar statistics and astrophysics. His first paper on proper motions of stars was published at Warsaw in 1925, but the most important ones were written during his two years at Lund and in Germany after 1930. In seven papers published in 1926-1933 Hufnagel considered the velocity distributions of faint stars and the influence on such distributions of accidental errors in proper motions. He cooperated on studies of this problem with K. G. Malmquist in 1933

and with F. Gondolatsch in 1931. During his stay in the United States, Hufnagel published two papers on stellar temperature and one note on galactic rotation (1929). With B. P. Gerasimovich, at the Harvard College Observatory, he investigated the semiregular variable star R Sagittae (1929). His last scientific paper, written with H. Müller (1935), concerned the absorption by interstellar clouds near the North America nebula. Hufnagel's main work in the last two years of his life was the elaboration of the first two chapters("Grundlagen der mathematischen Statistik") of Lehrbuch der Stellarstatistik, edited by E. von der Pahlen (Leipzig, 1937).

BIBLIOGRAPHY

I. ORIGINAL WORKS. Hufnagel's papers include “Die Bahn der grossen September Kometen 188211 unter Zugrundelegung der Einsteinschen Gravitationslehre," in Sitzungsberichte der Akademie der Wissenschaften in Wien, 128 (1919), 1261-1270; "Sur les mouvements propres des étoiles," in Bibliotheca Universitatis Librae Polonae, 13, fasc. A (1924); "Perturbations et tables approchées du mouvement de la petite planète (43) Ariadne," ibid., 14 (1925), written with J. Krassowski: "Über eine Formel der Stellarstatistik," in Astronomische Nachrichten, 228 (1926), 321-324; "Zur Geschwindigkeitsverteilung schwacher Sterne," ibid., 231 (1927), 297-304, and 242 (1931), 385–392, written with F. Gondolatsch; "Über die Räumliche Geschwindigkeitsverteilung der Sterne zwischen 9, und 14. Grösse,” in Meddelanden från Lunds astronomiska observatorium, 2nd ser., vol. 5 (1927); "On the Influence of the Accidental Errors in the Proper Motions on the Velocity Distribution," ibid., no. 114 (1928); "Über den Einfluss zufälliger und systematischer Fehler auf das Geschwindigkeitsellipsoid," ibid., no. 123 (1930); "Note on the Galactic Rotation," in Bulletin. Astronomical Observatory, Harvard University, vol. 863 (1929); "Temperatures of Giants and Dwarfs," in Circular. Astronomical Observatory of Harvard College, vol. 343 (1929); "Note on Stellar Temperatures," in Bulletin. Astronomical Observatory, Harvard University, vol. 874 (1930); "The Distribution in Space of the Stars of Type A as Derived From the Draper Catalogue," in Astronomiska Iakttagelser och Undersökningar på Stockholms Observatorium, vol. 11, no. 9 (1933); and "Untersuchungen über absorbierende Wolken beim Nordamerika Nebel unter Benutzung von Farbenindizes schwacher Sterne," in Zeitschrift für Astrophysik, 9 (1935), 331-381, written with H. Müller.

II. SECONDARY LITERATURE. Obituaries are in Astronomische Nachrichten, 248 (1933), 143; and Monthly Notices of the Royal Astronomical Society, 94 (1933), 276-277. EUGENIUSZ RYBKA

HUGGINS, WILLIAM (b. London, England, 7 February 1824; d. Tulse Hill, London, 12 May 1910), astrophysics.

Huggins was the second and only surviving child (the first had died in infancy) of William Thomas Huggins, a silk mercer and linen draper in Gracechurch Street in the City of London. His mother, the former Lucy Miller, was a native of Peterborough. He was precocious and, after a short period of attendance at a small nearby school and instruction at home under the curate of the parish, he entered the City of London School at its opening early in 1837. An attack of smallpox, from which he fully recovered, led to his removal from the school shortly afterward, his education being continued by private tutors at home. Although his formal instruction was broad, including classics, several modern languages, and music, his predominant interest was in science. A gift of a microscope led to early concentration on physiology, and although at about the age of eighteen he bought his first telescope-for £15-his location in the City of London was too unsuitable for celestial observations to allow astronomy to claim much of his attention.

At about this time (1842) family circumstances led to a regretful decision to abandon his intention of going to Cambridge for a university education, and he took over the responsibility for his father's business. From then until 1854 this was his chief concern, although his spare time was almost wholly given to the microscope and the telescope. Visits to the Continent, where his knowledge of languages stood him in good stead, helped to preserve the balance of his interests.

In 1852 Huggins joined the Royal Microscopical Society and in 1854 the Royal Astronomical Society, and in the latter year he was able to dispose of the mercery business and thereafter devote his whole time to science. He removed with his parents to Tulse Hill-now a part of greater London, but then situated in the country-and in the new surroundings astronomy prevailed over microscopy as his major interest. A not unimportant factor in this choice was his sensitive nature, which made experiments on animals distasteful to him. Huggins remained at Tulse Hill for the remainder of his life, setting up an observatory equipped with instruments, partly purchased by himself and partly lent by the Royal Society, and here the whole of his astronomical researches were carried out.

His father died shortly after the removal to Tulse Hill, but his mother survived until 1868; he felt her loss keenly. In 1875 he married Margaret Lindsay Murray, of Dublin, who, although twenty-six years his junior, was an ideal partner for the next thirty-five years, taking an active part in the astronomical observations; her name is associated with his in the authorship of some of his chief publications. She

seems, indeed, in this respect to have stood in a relation to her husband similar to that of Caroline Herschel to her brother William. She had also considerable artistic and musical gifts.

Huggins, although other interests ranked far below astronomy in his esteem, was by no means narrowminded. He was an able violinist-according to his wife, "always rather an intellectual than a perfervid player" and owned a fine Stradivarius instrument. Presumably it was the intellectual element in his musical talent that led to his contributing to the Royal Society in 1883 a paper on the proportional thickness of the strings of the violin-apparently his only publication, apart from one or two early papers on microscopical work, that was not astronomical in character. He was an expert pike fisherman and an admirer of Izaak Walton. Huggins had been brought up as a Calvinist but had never responded to this form of religion, and his views on such matters are perhaps best indicated by his wife's description of him as a "Christian unattached.” For a short time in 1870 he was attracted toward the scientific study of spiritualism and corresponded with Sir William Crookes on the subject, but his experience at séances led him to the conclusion that the subject was too closely associated with trickery to merit his serious attention.

Huggins' pioneer work in astrophysics brought him many honors. In 1865 he was elected a fellow of the Royal Society, and in the following year was awarded one of its Royal Medals. The Rumford and Copley Medals of the Royal Society followed in 1880 and 1898, respectively. In 1900 he became president of the Royal Society, a position which he occupied for the customary five years. His annual addresses in this capacity were collected and published in 1906 in a volume entitled The Royal Society, or Science in the State and in the Schools; here they were supplemented by many illustrations and material dealing with the history of the Royal Society and closely related matters. Huggins received the gold medal of the Royal Astronomical Society, jointly with W. A. Miller in 1867 and as the sole recipient in 1885; he was president of the Royal Astronomical Society during the two sessions 1876-1878. In 1891 he was president of the British Association for the Advancement of Science, and in 1897 he was created a K.C.B. and in 1902 awarded the O.M., one of the original members of the Order of Merit, which had just been instituted. Numerous universities conferred honorary degrees on him. His financial resources, although sufficient to allow him to devote the whole of his time to astronomy, were not great; and in 1890 he was awarded a Civil List pension of £150 a year in recognition of the value of his work.

In 1908, when he felt no longer able to continue

his researches, Huggins returned his instruments to the Royal Society; and they were transferred to the Solar Physics Observatory at Cambridge, where they now are. He died on 12 May 1910, following an operation.

Huggins' earliest astronomical work was on conventional lines. He formed a close friendship with W. R. Dawes, a well-known amateur observer, from whom he bought an eight-inch refracting telescope; and with this, between 1858 and 1860, he made observations of the planets. In 1859, however, Kirchhoff had shown how, from observations of the dark Fraunhofer lines in the solar spectrum, the chemical composition of the sun's atmosphere could be determined; and Huggins gave the first manifestation of one of his most marked characteristics-that of immediately perceiving the possibilities opened up by a new discovery. "This news came to me," he wrote later, "like the coming upon a spring of water in a dry and thirsty land." It at once occurred to him that this method could be applied to the stars; and he confided his idea to his friend W. A. Miller, professor of chemistry at King's College, London, who, although somewhat dubious, agreed to collaborate with him. They designed a spectroscope consisting of two dense flint glass prisms which they attached to Huggins' eight-inch telescope, and observations of stellar spectra were begun. The same idea had occurred to Rutherfurd in America, but quite independently. In order to interpret the stellar spectra it was necessary to obtain better knowledge than that which then existed of the spectra of terrestrial elements; and maps of twenty-four such spectra were prepared by Huggins, with the use of a more powerful spectroscope containing six prisms. In 1863-1864 the stellar and laboratory observations were published by the Royal Society, the general conclusion reached being that the brightest stars, at least, resembled the sun in structure, in that their light proceeded from underlying hot material and passed through an atmosphere of absorbent vapors; nevertheless, there was considerable diversity of chemical composition among the

stars.

Striking as this conclusion was-much more so then than now, when it has become a commonplace-a still more sensational discovery was made in 1864. The nature of the nebulae was then quite unknown: "a shining fluid of a nature unknown to us," which was William Herschel's description of a nebula, had remained all that could safely be said on the matter. The fact that an increasing number of them had, after Herschel's time, been resolved into star clusters as more powerful telescopes became available, had led to the conjecture that all were of this character and would be so observable with instruments of sufficient

resolving power. It occurred to Huggins to attempt a verification of this by observation with the spectroscope. He accordingly directed his instrument toward a planetary nebula in the constellation Draco and observed not, as he expected, a mixture of stellar spectra but a few isolated bright lines. His knowledge of laboratory spectra at once suggested the interpretation of this: the nebula consisted not of a cluster of stars but simply of a luminous gas. Other nebulae were examined; some showed similar spectra and others spectra generally resembling those of stars. It became clear that these objects, up to then regarded as identical in nature, belonged to two classes: some were clusters of stars, which would be seen as such with greater telescopic power, while others were uniformly gaseous. The bright lines observed in the gaseous nebulae, however, presented a puzzle. Hydrogen was readily identifiable, but there were other lines corresponding to nothing known on the earth; and a new element, provisionally called "nebulium," was postulated. It was not until 1927 that it was discovered by Ira S. Bowen that nebulium was ionized oxygen and nitrogen.

Huggins followed up this work by spectroscopic observations of comets and of a nova, or new star, which appeared in the constellation Corona Borealis in 1866. He showed that the radiations of three comets gave spectra containing bands coincident in position Iwith those obtainable from a candle flame in the laboratory, and concluded that they arose from carbon or its compounds. Huggins was more attracted by the fainter than by the brighter celestial objects and gave little attention to the sun. It was accordingly his younger contemporary Norman Lockyer who discovered how to make spectroscopic observations of the solar prominences in full sunlight. On hearing of this achievement, Huggins supplemented it by simply widening the slit of the spectroscope, thus revealing a prominence in its natural form, in the light of each element that it contained, instead of merely by a narrow spectrum line.

Another example of Huggins' opportunism is afforded by his early perception of the possibility of applying the Doppler effect to the determination of the motions of the stars in the line of sight. It was in 1841 that the Austrian physicist Christian Doppler deduced on theoretical grounds that the motion of a source of sound or light-both regarded as wave phenomena toward or away from an observer should cause a change in the frequency of reception of the waves, manifesting itself as a change of tone with sound and a change of color with light. He did not reach a full understanding of the effect of this change on stellar observations, for he thought that it would

make a receding star appear redder, and an approaching star bluer, than if the star were stationary. In fact, since stellar spectra extend into the invisible regions of the infrared and the ultraviolet, all that radial motion could do would be to shift the whole visible spectrum slightly to one side or the other; its whole range of colors would still appear, leaving the resultant color unchanged. Fizeau later pointed out that, nevertheless, use could be made of the effect because the absorption lines in the spectra would partake of this general displacement; and the amount of their shift-measured by the difference of wavelength of the stellar lines and the lines of the same substances produced from stationary sources in the laboratory-would indicate the velocity of the star along the line of sight, the so-called radial velocity.

Huggins at once perceived the possibility of applying the knowledge he had obtained of the laboratory spectra of elements to the determination of such velocities. He consulted Clerk Maxwell on the theory of the matter; and after various delays in securing a sufficiently powerful spectroscope he succeeded, in 1868, in obtaining a value for the radial velocity of Sirius of 29.4 miles a second away from the sun-a figure which later, with better instruments, he amended to between 18 and 22 miles a second. This is now known to be too large, although the direction is right; but it must be remembered that only visual observations were then possible and that the attainable accuracy of measurement fell short of that which we now regard as essential for this work. The principle had been established, however, of introducing into astronomy one of the most fruitful sources of knowledge we possess concerning the structure and evolu

tion of the universe.

Although, as has been said, these observations were visual, Huggins had not overlooked the desirability of photographing stellar spectra; and as early as 1863 he attempted to photograph the spectrum of Sirius, the apparently brightest star in the sky. But the result was poor, and he realized that the time for this refinement had not come. Satisfactory results were not obtained until 1872, by Draper; and Huggins was not slow to follow them up by extensive photographic observations of the spectra of stars bright enough for this type of examination. He also sought to apply spectroscopic photography to the detection of the solar corona in full sunlight and at first thought he had succeeded, but this hope was not confirmed. Nevertheless, he devoted his Bakerian lecture to the Royal Society in 1885 to the subject "The Corona of the Sun."

Pursuing his studies of the nebulae, Huggins came into conflict with Lockyer, another pioneer in spec