1882.] 



KNOV/LEDGE 



U7 



DR. HENRY DRAPER. 



BUT a few short months ago wc had to record the 

 death of Dr. J. W. Draper, in the fulness of age, 

 and after a life devoted to scientific, literary, and profes- 

 sional labours. We had it in our thoughts then that he 

 left behind him three sons, all students of science, and one 

 already so distinguished that there was every reason to 

 regard him as following as closely in his father's footsteps 

 as .John in the footsteps of William Herschel. But those 

 hopes must remain unfulfilled, and science must rest con- 

 tent with the good work which the young Draper was able 

 to complete in the short space of life allotted to him. 



Born in Virginia, on March 7, 1837 — the son of an 

 English father and a Spanish mother — Henry Draper was 

 brought up in Xew York, and would have been recognised 

 as a Northern American by all familiar with the diversities 

 of type co-existing in the United States. He graduated in 

 1S58 at New York University, where his father was Pro- 

 fessor of Chemistiy ; and in 1860 he was elected to a 

 professorship there. In 1866 he became Professor of Phy- 

 siology in the Medical Department. 



Dr. Draper's achievements in science have nearly all 

 been associated with the application of photogi-aphy to the 

 increase of our knowledge. He, more, perhaps, than any 

 man in our time, has shown the power of the photographic 

 eyes of science. Thus, in 18.57, he used microscopic pho- 

 togi'aphy to aid in a series of researches into the function 

 of the spleen. He next became famous for his labours in 

 celestial photography, making, io't/- iiHk, a remarkably fine 

 photograph of the moon (which hangs before us as we 

 write), with a loi-inch reflecting telescope of his own con- 

 struction. Later, he made a fine reflecting telescope of 2 1 

 feet in aperture, the speculum being of silvered glass. 

 With this, in 1872, he attempted the then most arduous 

 task of photographing the spectra of the stars. Later, 

 using the sensitive gelatine plates, he achieved a marked 

 success in this stDl difficult work. He brought the spectra 

 of the stars into direct comparison with the spectrum of 

 our own star, the sun, using as reflecting adjuncts to his 

 telescope the planets Jupiter and Venus, to give the solar 

 spectrum with sufficiently reduced light. His photograph 

 of the diflraction spectrum in 1872 — from near the U line 

 to line O in the invisible part beyond the violet — has 

 justly been regarded as one of his most successful achieve- 

 ments. 



In 1874, Dr. Draper's reputation in celestial photography 

 led to his being appointed Superintendent of the Photo- 

 graphic Department of the American Venus-Transit Com- 

 mission ; and he worked so successfully and disinterestedly 

 in the discharge of the duties thus entrusted to him, th.at 

 the L^nited States CJovernmcnt did honour to themselves 

 by causing a special gold medal to be struck at the Phila- 

 delphia Mint, bearing the motto, " Becori Bcciis Addit 

 .Irito,"* in which his father's fame is worthily linked with 

 his own. In 1877, Dr. Draper undertook a long journey 

 to the Rocky Jlountains, to experiment on the etiocts of 

 the greater steadiness ond clearness of the air at an eleva- 

 tion of 11,000 feet above the sealevel. He led a party 

 the following year to the same region to observe the total 

 eclipse of July, 1878, and succeeded in photographing the 

 diflraction spectrum of the corona. 



During the autumn and winter of 1880 81 he photo- 

 graphed the nebula in Orion. Our contemporary Xtitiin^ 

 says " last autumn and winter " he took such photographs, 

 which " wei'B the first he ever made;" but this is an error : 

 in April, 1881, we had the pleasure of examining in his 



* l{o adds renown to fame iiihentod. 



laboratory the first one-inch negatives he had obtained, 

 showing a marvellous amount of detail in the nebula, 

 closely resembling what is shown in the drawings made 

 by Trouvelot at the Washington Observatorj', and lat<'r 

 — in May, 1881 — we saw the improved positives (much 

 enlarged) of the Great Nebula. Of these, which had been 

 then recently completed, one lies before us as ,we write, 

 bearing the date on which it was presented to us, " May 16, 

 1881." Later he applied photography to the more difficult 

 and delicate task of recording the spectrum of the nebula in 

 difterent parts, and he also photographed the Spectrum of 

 Wells' Comet 



But the work with which his name will chiefly be asso- 

 ciated is that which for this reason we have left to the last, 

 his recognition— still by aid of celestial photography— of 

 the existence of oxygen, and probably nitrogen also, in the 

 sun. Of the ingenious methods by which he mastered the 

 difliculties in the solution of the problem of comparing 

 the spectrum of our air with that of the sun, we need not 

 speak here. They would occupy, indeed, much space ; but 

 they have been already fully described by us elsewhere. 

 Sufiice it, that the result satisfied all save a very few- — 

 whose opinion was perhaps biassed — that oxygen Js present 

 in the solar atmosphere in such a condition that, emitting 

 more light than it absorbs, it makes its presence known by 

 bright lines. 



The loss sustained by science in the early death of so 

 honest and zealous a worker is that which we must chiefly 

 consider here. But it is impossible for those who knew 

 Dr. Draper personally to omit some reference to his quali- 

 ties as a man. Kindly, genial, and bright^ he was a living 

 contradiction to the common idea that the ardent student 

 of science must be a man of worn and gloomy aspect, 

 serious, if not morose, in disposition, uncheerful in tem- 

 perament He spoke of the results of patient, long-con- 

 tinued toil, as a boy might talk of a trophy won at cricket 

 or base-ball. He passed lightly over the wrongheadedness 

 of envious (because less successful) workers in his field of 

 labour. Blessed with the companionship of a wife who 

 shared his aspirations, encouraged his labours, rejoiced over 

 his successes, and sympathised when less complete success 

 than he had hoped for rewarded him, he pursued his work 

 earnestly and zealously. With that lady, all who know 

 her and knew her husband's worth will warmly sympathise. 

 We sorrow ourselves in the loss of a most valued friend, 

 with whom we had hoped to foregather again before many 

 months were past, and for years, if life had been granted 

 us, to have heard in his own country (our home before 

 long), and from his own lips, the recital of his hopes and 

 fears, his partial failures and his final triumphs. Of the 

 same age as himself, within sixteen days, and recognising 

 in him, as we thought, a man of enduring constitution, 

 we should have lioped for him a longer space than for 

 ourself by many years. But it was not to be, and science 

 has to mourn the premature death of one of the most 

 faithful of her servants. 



Aeri.\i. NAVifiATiOK. — M. De Comlierousse, in adiscourso 

 pronounced at the funeral of the late Henri GifTard, made 

 this significant admission : — " An intimate friend of Gifl'ard 

 told me yesterd.iy that he carried to the tomb the secret 

 which he liad long sought for, and which had revealed itself 

 to his eyes during his last years. He added tliat our 

 colleague shrank back from his own discovery, and, filled 

 with horror, put an ci\d to his existence." In other word", 

 he saw at length that aerial navigation must prove the 

 suicide of civilisation. 



