334 Prof. Piazzi Smyth on the Constitution of the Lines 



Professor Henry Draper, of New York, from a series of 

 experiments made with extraordinary skill and power, 

 announced that oxygen appears in the solar spectrum not in 

 its dark but in its bright lines, outshining where they come 

 the brightness of the sun's continuous-spectrum background. 

 Yet, though he gallantly made a voyage from New York to 

 London especially to describe his experiments, and was 

 honourably received and attentively heard, there are some 

 persons there who are not convinced yet. 



Now Dr. Schuster had already compared his four lines, 

 though of the low-temperature oxygen-spectrum, with Ang- 

 strom's normal solar-spectrum map, under the idea apparently 

 that, though the solar oxygen might have been rendered in- 

 candescent in the very hottest central regions of the sun, it 

 might have its Fraunhofer dark correspondences checked off 

 by cooler oxygen vapour outside. But as his then knowledge 

 of oxygen low-temperature lines made them only four single, 

 simple, thin lines, the comparison was not attended with any 

 very certain result ; for there are so many of such lines, un- 

 claimed for any element, strewed all along the solar spectrum. 

 But now that I had found four out of five lines to be triplets 

 of an accurate kind, could any thing further in the way of 

 identification be ascertained ? 



In apparently the very place of the three fainter of the 

 above-described triplets there is a close double of peculiarly 

 thin Fraunhofer lines depicted by Professor Angstrom in his 

 normal solar-spectrum map ; and in the place of the brightest 

 of them, viz. Schuster's orange line, there is a triple* of the 

 same kind of ultra thin lines ; and not one member of all 

 those four groups has been claimed for any known element by 

 the great Swedish physicist. Yet I am by no means satis- 

 fied that the degree of correspondence is conclusive, and can 

 only hope that those who have the means will positively con- 

 front the new oxygen triples with the sun itself and inform 

 us what they find. 



Oxygen of the Ear tit s Atmosphere in the Telluric Solar 



Spectrum. 

 If the long silence of the spectroscope touching oxygen in 

 the sun was a wonder, and perhaps something the reverse of 

 praise to those who used the supposed all-powerful instrument, 



* That triplicity is indeed there broken in upon by a far stronger line, 

 which Angstrom traces to sodium (Na) ; but such cases of mere optical 

 juxtaposition aie frequent in the crowds of lines in much of the solar 

 spectrum, without any physical connexion being supposed to be implied 

 thereby. 



