476 0. T. Sherman — Bright Lines in Stellar Spectra. 



When the series of observations was first commenced there 

 were recognized in the spectra but a few bright lines, so situ- 

 ated as to be probably the hydrogen lines, D 3 , and in addition 

 1474(K) and 1250(K). As the observer became accustomed 

 to the spectrum of ft Lyras it became apparent that there were 

 also other bright lines. With the single series of prisms ten 

 such were counted. 



Eecalling now the course of reasoning whi.ch led to the day- 

 light observation of the solar prominence, and also that many 

 more bright lines than those already recognized were seen in 

 the spectrum of the solar atmosphere, I employed the highest 

 dispersion obtainable. The number of bright lines was in- 

 creased to seventeen. It seems extremely probable that an 

 increased dispersion will bring out many more. Arrange- 

 ments for so improving the apparatus are in progress. The 

 story for y Cassiopeia? is similar. 



The instrument has been turned upon numerous other 

 stars and in each case many or few bright lines have been 

 seen, lines, so far as I know, formerly unsuspected. The 

 careful description awaits the completed apparatus. At 

 present it would seem that the lines are most easily seen in 

 the red stars. This may be a mistake. The word lines is 

 here used only by analogy to signify bright stellar images. 

 At the red end under a sharp focus they stand out the full 

 breadth of the spectrum, bearing somewhat the same relation to 

 the background as the prominence to the solar spectrum. In 

 the brighter portion of the spectrum they are cut down to fine 

 star points. At the blue end they become more distinct but 

 not so sharp as at the red. At times they shine with almost 

 a metallic brilliancy; at other times they are faint, faded, and 

 easily passed over. Certain sets appear to be prominent at 

 times, others at other times. 



The difficulties of the observation, and the roughness of the 

 recording apparatus have hindered a completely satisfactory 

 identification of the lines. Assuming the position of the hydro- 

 gen lines and of D s , and on their basis drawing the curve con- 

 necting scale reading and wave length, the mean of nine ob- 

 servations upon y Cassiopeise affords the following approximate 

 wave lengths. The positions of the dark lines are underlined. 



Ha, 635-6, 628, 616, D„ 584 ? £[6, 555-75, 542-2, 530-98, 



516-75, 502, 499-0, 492, H/3, 467-35 , 462-3, By 418 ? H«j, 399-3. 



It is of interest to compare these with the following wave 

 lengths taken from Prof. Young's catalogue of lines observed 

 at Sherman :* 



Ha, 634'6, 61406 D„ 585*27, 5534, 544'59, 531-59, 516-83 

 and 516-67, 501-76, H/?, 457, H 7 , 421-5, H*. 



* This Journal, Nov., 1872. 



