454 Hutchins and Holden — Elements in the Sun. 



For reasons readily apparent, it was found so difficult to 

 photograph under high dispersive power those parts of the 

 spectrum not lying between wave-length 3600 and wave-length 

 5000, that our photographic work was done chiefly within 

 those limits. It was, however, supplemented in many cases by 

 eye observations in other portions of the spectrum. 



We are convinced that there is much in the whole matter of 

 coincidences of metallic and solar lines that needs re-exam in 

 tion ; that something more than the mere coincidence of two 

 or three lines out of many is necessary to establish even the 

 probability of the presence of a metal in the sun. With the 

 best instruments the violet portion of the solar spectrum is 

 found to be so thickly set with fine lines, that, if a metallic line 

 were projected upon it at random, in many places the chances 

 for a coincidence would be even, and coincidences could not 

 fail to occur in case of such metals as cerium and vanadium 

 which give hundreds of lines in the arc. 



Moreover, a high dispersion shows that very few lines of 

 metals are simple and short, but, on the contrary, winged and 

 nebulous, and complicated by a great variety of reversal phe- 

 nomena. A "line" is sometimes half an inch wide on the 

 photographic plate, or it may be split into ten by reversals. 



At first, we believed that these reversals were due to defects 

 in the ruling of the grating, but we are convinced that they are 

 true phenomena from the following experiments. 1st. The 

 wings continue when various portions of the grating are cov- 

 ered. 2d. They are the same in three successive orders of 

 spectra. 3d. Theyare very different in different metals, and 

 in some are not seen at all. 4th. We arranged a flat grating, 

 with collimator and projecting lens, each of five feet focus, and 

 found that with this apparatus the same phenomena appeared. 



Qn 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 byLock- 

 yer at wave-lengths 4677 and 4799 is perfect. These are the 

 only cadmium lines near, and the 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 photo- 

 graphed 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 pronounce upon; it 

 may coincide. 



Cerium, Molybdenum, Uranium and Vanadium. — These four 



