17G Mr. J. N. Lockyer'ofl Solar Chemistry. 



this portion of the spectrum. I have here enlargements of 

 negatives going nearly the whole length from G to H, one of 

 the regions which are included in this photograph of Dr. Dra- 

 per's. I have carefully gone over these regions line for line; 

 and in no case do I see any bright line in the sun whatever 

 coincident with any line of oxygen whatever. I cannot pro- 

 fess to have gone over the ground in the ultra violet ; but it 

 will appear to me very surprising indeed if, when we go fur- 

 ther, when we include the H and K lines which have already 

 been thrown on the screen, that Dr. Draper will find any 

 possible coincidences with bright lines of the sun even there, 

 because, when perfect instrumental conditions are brought into 

 play, no bright line whatever exists in the part of the solar 

 spectrum which is included in this map. 



The bright line discovered by Cornu exists outside K; 

 but between the region included in this map and the G lines I 

 find no obvious bright line. 



There is an experiment which any member of the Physical 

 Society who possesses a spectroscope with three or four prisms 

 can make for himself. Take the spark in air in an apparatus 

 of the kind to which I have referred, use a comparison prism, 

 flood the air with nitrogen, and in the field of view which 

 includes b (and therefore one of the most marked bright lines 

 in the solar spectrum itself) you will find three or four un- 

 doubted lines of oxygen. I have made that experiment, which 

 is quite a simple one ; and I find no coincidences in this part 

 of the spectrum between any of these oxygen-lines and the 

 undoubted bright lines. I have not tried it yet for the lower 

 parts of the spectrum in the red and yellow, because I hope 

 that Dr. Draper will try for himself. 



I do not say that Dr. Draper's alleged discovery is no dis- 

 covery at all ; I say (and I think it is my duty to say it, as I 

 have been occupied in closely allied work for some considerable 

 time) that I do not hold it to be established. 



I have no doubt that Dr. Draper will carefully go over his 

 work himself; and I am quite certain that he will be the very 

 first to hail what I have said today with satisfaction, because 

 his desire, I am sure, is the desire of every true man of science, 

 that the truth should prevail. In any case Dr. Draper has 

 begun work in a branch of the chemical inquiry into solar 

 matters which, up to the present time, has been sadly neg- 

 lected ; and we should all be grateful to him on that ground. 

 I have no doubt that he on his side, as I on mine, hopes, 

 as I said before, that the Physical Society of London and the 

 Physical Societies of America will come forward and supply 

 more workers for a branch of science which I am .certain in the 

 future will be regarded as one of very considerable importance. 



