264 Trowbridge and Hutchins — Oxygen in the Sun. 



and most complete investigations have left the minds of scien- 

 tific men still in doubt, has led the writers to take up the ques- 

 tion again with more perfect and powerful apparatus and in- 

 creased facilities, in order if possible to add something to the 

 knowledge of the subject. 



The question of the existence of oxygen in the sun was first 

 seriously investigated, we believe, by Dr. Henry Draper, who 

 published in the American Journal of Science for 1877 and 

 1879, and in foreign journals, papers accompanied by repro- 

 ductions of his photographs. Dr. Draper was firmly persuaded 

 of the existence of oxygen in the sun's atmosphere, and based 

 this belief upon the apparent coincidence of the lines of oxygen 

 taken in air with certain bright spaces in the sun's spectrum 

 which appeared upon his photographs. 



Prof. John Christopher Draper published a paper in the 

 American Journal of Science for 1878, in which he stated his 

 conviction that oxygen exists in the sun ; but his line of argu- 

 ment was just the reverse of that of Dr. H. Draper. While the 

 latter apparently proved the existence of oxygen in the sun 

 by the coincidence of its bright lines with bright spaces in the 

 solar spectrum, the former was led to believe that the bright 

 oxygen lines coincided with dark lines in the sun. 



Both observers abandoned the old method of eye observation, 

 and took advantage of the improvements in photography to 

 record the oxygen lines upon a sensitive plate. Dr. H. Draper 

 was led to abandon Geisler's tubes filled with oxygen, and to em- 

 ploy the electric spark in common air, on account of the greater 

 brilliancy of the lines, while Prof. J. 0. Draper still adhered to 

 tubes filled with rarefied oxygen. The oxygen lines had been 

 mapped by previous observers, notably by Thalen, and Schuster 

 had shown that there were four spectra of oxygen which could 

 be produced under varying conditions of temperature and 

 pressure. 



The photographs of Dr. Henry Draper's oxygen spectrum, 

 together with the juxtaposed solar spectrum, were submitted to 

 the French Academy of Sciences in Paris, June 23, 1879, by 

 M. Cornu. From the remarks of M. Faye we make the follow- 

 ing extract : — - 



"Dr. H. Draper has, however, succeeded in discovering oxy- 

 gen, not in the chromosphere, but in the photosphere, where it 

 discloses itself by bright lines. It is obvious that this gas is 

 dissociated at a depth, and is immediately taken up by multi- 

 ple combinations in the region and at the temperature of the 

 brilliant surface. I see in these facts the hope of a confirma- 

 tion, and above all of an extension, of the views I have put 

 forth on the constitution of the sun ; but whatever may be the 

 fate that the progress of spectrum analysis reserves to them, 



