328 Messrs. Hutchins and Holden on the 



covered. (2) They are the same in three successive orders 

 of spectra. (3) They are very different in different metals, 

 and in some are not seen at all. (4) We arranged a flat 

 grating, with collimator and projecting lens, each of 5 -feet 

 focus, and found that with this apparatus the same phenomena 

 appeared. 



On pages 87 and 88 of 'The Sun'' Professor Young 

 gives a list of elements in the sun according to the best 

 authorities, which is followed by a list of doubtful elements. 

 Some of these we have examined with the following results: — 



Cadmium. — The coincidence of the two lines given by 

 Lockyer at wave-lengths 4677 and 4799 is perfect. These 

 are the only cadmium-lines near, and sun-lines in the vicinity 

 are not numerous. 



Lead. — The evidence for lead, due to Lockyer, is based 

 upon three lines at 4019-7, 4058*2, and 4061*8. We have 

 photographed these lines with the sun many times. They are 

 broad and nebulous, and often several times reversed. Lines 

 in solar spectrum numerous and faint. 4019*7 and 4058*2 

 certainly do not coincide. 4061*8 is very difficult to pro- 

 nounce upon ; it may coincide. 



Cerium, Molybdenum, Uranium, and Vanadium. — These 

 four metals may be classed together. Lockyer finds four 

 coincidences each for molybdenum and vanadium, three for 

 uranium, and two for cerium. The arc-spectrum of each is 

 characterized by great complexity and vast numbers of lines. 

 So numerous are the lines, in fact, that often on the photo- 

 graphs the total space occupied by them is greater than the 

 space not so occupied. A plate 10 inches long may contain 

 a thousand or so. Evidently coincidences between these and 

 solar lines cannot fail to occur as matters of chance, and 

 therefore prove nothing. One can easily count a hundred or 

 so such coincidences without the slightest conviction that the 

 connexion is other than fortuitous. Of course all this is 

 nothing against the probability of these metals being in the 

 sun ; but at the same time those peculiarities of grouping, 

 strength of lines, and other characteristics which occur in the 

 case of iron and other spectra, and which alone can serve as 

 evidence in such cases, are conspicuously absent. 



Among the metals whose existence in the solar atmosphere 

 has seemed probable, we have examined the following : — 



Bismuth. — The line of the above metal at 4722*9, the only 

 line of bismuth in the arc in that whole region, coincides per- 

 fectly with the more refrangible of a very faint pair of solar 

 lines. 



