The late Sir William Huggins.

Progress, Volume V, Issue 11, 1 September 1910, Page 375

The late Sir William Huggins.

A Pioneer Astrophysicist. The death of Sir "William Huggins, which took place in London on May 12th, closes a long life of useful activity devoted to pure science, a life full of recognition and honours. If official recognition of his merits came late in his life — as it often does in this country, as well as in others — official honour was finally meted out in full measure, while his fellow-scientists had from the first paid tribute to the distinguished work in astronomy and solar physics accomplished by an earnest worker who was not a professor, not connected with any of the great national institutions, nor even a graduate of any English university, all his degrees being honorary. He was in his seventy-fourth year when the Order of the Bath, together with the knighthood, was conferred upon him on the occasion of the Queen's Diamond Jubilee; in 1902 the late King made him one of the twelve original

members of the Order of Merit. (The Royal Society elected him a fellow in 1865, two years after the presentation of his first paper; honorary degrees, medals, and other distinctions followed, and in 1900 Sir William Huggins succeeded Lord Lister as President of the Royal Society. As such he presided over the inauguration of the National Physical Laboratory by the present King and Queen, while the numerous foreign distinctions awarded to him testify to the general esteem in which he was held all over the world. ' William Huggins was born in London on February 7th; 1824, /and was thus in his eighty-seventh year, when he died after an illness of only one day. He was educated at the City of London School and at home. Private tutors instructed him in classics, mathematics, and science, and it must not be thought that the 1 Royal Society somewhat deviated from its 'custom by offering the presidency to one of their members who had confined his studies to one branch of science. Young Huggins, in fact, was long in doubt whether he should take up

physiology and microscopical research, or pursue his life study chiefly with the aid of the telescope. His decision in favour of the telescope came at an opportune period. It was only a few years after he had been able to erect a telescope of his own at Tulse Hill, in 1856, that Kirchhoff pnd Bunsen published at Heidelberg, in 1859, the researches which at once put spectrum analysis on the footing of a novel and most important means of investigation. Many physicists, like Kirehhoff and Bunse, began to examine the sun; others went further and sought to ascertain whether the starry world gave evidence of containing the same constituents or some of them which it was then known or believed made up the earth and sun. In this work Huggins collaborated with his friend, W. Allen Miller, professor of chemistry at King's College. A star spectroscope did not then exist, of course; it had to be created. The light of the stars is exceedingly weak, and the identification of the lines of the spectrum with the instruments then available was most difficult. Progress was, in fact, in the first years of stellar spectroscopy, as Sir William Huggins himself later remarked, "much retarded by resting important con elusions upon the apparent coincidence of single lines, in spectroscopes of very small resolving power." By 1863 Huggins and Miller presetted their first joint paper to the Royal Society, a "Preliminary Note on the Lines of Some Fixed Stars." The very day, it is said, that they read this paper they were informed that Rutherford, in the United States, and Secchi, in Italy, were engaged in similar work. The question of priority was hotly contested, not by the chief workers, but by their friends. Huggins never Mas the man to speak of his own achievements. His modesty could not but strike even the most casual acquaintance. But his friends felt all the more called upon to urge his claims. The whole controversy was futile. It would, indeed, have been astonishing if stellar spectroscopy had been initiated without some such coincidence, and in fact one cannot now help wondering a little that the discovery of spectrum analysis should have lain dormant so long a time. In stating this we do not in the least desire to deprive Kirchhoff and Bunsen of the credit which is so justly accorded to them for their remarkable systematic investigation. A few words will explain our reasoning. Fraunhofer himself wrote in 1817 that, to judge by the (Fraunhofer's) lines, the light of Venus and of Mars was that of the sun, while the light of Sirius differed; in other stars, moreover, he observed different bands in 1821. J. F. Hersehel stated in 1835 that the series of "fixed lines" in the spectrum of stars like Sirius was totally different from that of any known terrestrial flame. The elder' Hersehel had observed in 1823 that the yellow" s'odi'o.in flame was characterised by a yellow find it was apparently 1 the übiquity of this line which prevented him and" others 'from following the problem up. Still more

noteworthy is Wheatstone 's report of 1835 to the British Association, in which he describes the lines seen in an electric spark when striking into mercury; there were the two D lines, one green, one blue, one indigo, one "violet line, and sparks from other metals, he noticed, gave other lines. Continuing their studies, Huggins and Miller examined in their laboratory the puzzling differences between the spectra obtained under different conditions. One of his later successful researches, carried out in conjunction with Lady Huggins, who, after his marriage in 1875, had become his. able and enthusiastic assistant and joint- author of his memoirs, should be mentioned in this connection. It had been noticed that the general sun spectrum displayed seventy-two calcium lines, while in the spectra of the chromosphere and of the prominences, only two lines could be attributed to calcium. That discrepancy was so strong that the whole identity of the solar calcium lines was questioned; everybody is aware what an importance it attached to calcium vapours in the solar atmosphere. In 1897 Huggins established that at sufficiently reduced pressure the number of calcium lines was, indeed, diminished to two. This difficulty having been cleared up, spectro-photography in calcium light could take its established position. Stellar spectro-photography had been attempted by Huggins in the early sixties. But the imperfection and unsuitability of the old silver plates and of the wet collodion plates, which were then alone available, baffled his endeavours. When he resumed this branch in the seventies, the gelatinebromide plate — almost perfect, apart from its grainy texture, as he remarked in his presidential address to the British Association in 1891 — had been invented, and, thanks to the interest that the Royal Society took in his work, he was in possession of a 15-inch refractor and an 18inch reflector, fitted with mirrors of speculum metal, besides a spectroscope provided with quartz lenses and prisms of Iceland spar, which did not stop the ultraviolet rays. Thus he was able to study the spectra of stars with a view to their classification, as proposed by Secchi in 1863, and modified by H. C. Vogel in 1874. The order in which Huggins arranged the stars from their photographic spectra in 1879 was essentially that of Vogel — to quote Huggins 's own words. Soon afterward he was able to show that the star-like nuclei in the Orion nebula really belonged to the nebula, and were not in front or behind the nebula. He had been studying nebulae since 1864, and had been able to decide whether nebulae were to be regarded as portions of the fiery mist or shining fluid, out of which, in the elder Herschel's words, the heavens and the earth had slowly been fashioned, or whether they were external galaxies, cosmieal "sandheaps," too remote to be resolved into separ.ite stars. The spectrum of the nebula in Draco proved to be the bright line spectrum of a glowing gas upon a background of a faint continuous spectrum. Turning his attention to the spectrum of comets, Huggins found carbon vapours in it, thus confirming a suggestion thrown out by Donati in 1858. Laboratory experiments on olefiant gas and other hydro carbons confirmed Huggins in his opinion that hydro carbons were to be found in the constituents of comets. When delivering the Bakerian lecture in 1885, Huggins

regarded the corona of the sun as similar in the cause of its formation to the tails of comets — that is, consisting for the most part of matter going from the sun under the influence of some force, probably electrical. Many of the corona particles might return to the sun, but those forming the long streamers did not return, and diffusing they might, he suggested, go to furnish the matter also of the zodiacal light. The cometary matter he considered identical with that of meteorites. One of the signal triumphs of the work of Huggins was his application of the Doppler principle to the study of the motion of stars in the line of sight. In his original paper on "Das farbige Licht der Sterne," published in 1841 at Prague, Doppler had suggested that the difference in colour observed in some binary stars might be produced by their motion. Doppler was right in so far as the principle is as true in the ca=e of light as it is in the ease of sound ; but he was wrong in supposing that a change in colour would actually be recognised, even if the star were moving with such an enormous velocity as to alter sensibly its colour to the eye. Huggins understood that the principle became applicable as soon as lines of known substances had been recognised in stellar

spectra, and his first observations of 1868 were soon confirmed by Vogel and Schemer at Potsdam, by Christie at Greenwich, and later by Keeler at the Allegheny and the Lick observatories. The latter was also so fortunate as to measure, Avitli the magnificent instruments at his disposal, the motion of planetary nebulae in the line of sight. How greatly this important method of research has since been developed by able observers on both sides of the Atlantic is now well known. Huggins also was a pioneer in solar physics. The suggestion that it would be possible to observe solar prominences any day — not only during solar eclipses — with the aid of the spectroscope was due to him. The idea was that the spectrum of the prominence would be sufficiently brigfht, while the prisms would disperse the airglow. Huggins also suggested — and Zoellner at the same time — that if a wide slit were slowly removed from the limb of the sun, the prominence would record its own width at different distances from the limb, and thus its shape. The first actual observations of this kind were secured by Janssen in 1868.

When the phenomena of radioactivity were investigated early in this century, Huggins took up the spectroscopic side of the problem. We cannot, however, furthe-r specify his work on the present occasion. That he continued to excel is best proved by a long series of distinctions conferred upon him. The Order of Merit, which we have already mentioned, he valued highest. The Eoyal Society, which admitted him in 1865, awarded him a Royal Medal in 1866, the Rumford Medal in 1880, and the Copley Medal, the highest honour at its disposal, in 1898. The Eoyal Astronomical Society, whose president he was in 1876, had given to him and to Miller a gold medal in 1867. Honorary degrees had come from Cambridge in 1869, when he was Rede" lecturer, and from Oxford soon afterward. The Paris Academy awarded him the Lalande Prize for astronomy in 1872, and the Prix Janssen of the Institut fell to him in 1888. He also held the "Wilde and the Draper Medal, and the Medal of the Pacific Astronomical Society. During his presidency of the Royal Society in 1900 to 1905 he accentuated the value of the study of science against the advocates of humanistic studies, and selection from his presidential addresses to the Royal Society were published in 1906 under the title "The Royal Society, or Science in the State and in the School." His most important works are the "Publications of Sir William Huggins 's Observatory," of which the first volume, entitled "An Atlas of Representative Stellar Spectra," appeared in 1899, while the second volume, "The Scientific Papers of Sir William Huggins, X.C.8., 0.M.," was published only last year. In 1875 Sir William Huggins had married Miss Margaret Lindsay, daughter of Mr. John Murray, of Dublin, herself a great astronomer and joint-author with him also of the atlas just mentioned. — Engineering.