260 Sir J. K Lockyer and Mr. Baxandall. Enhanced [July 13, 



1. Probably partly due to the enhanced Fe line, in addition to Mn and Or. 



2. Solar line probably due partly to p Fe. K and R's A 4055'63 (4). 



3. Solar line probably compounded of the p Fe and Mn lines. 



4. The p Fe line is apparently slightly more refrangible than solar line 4462*37. 



5. This p Fe line is probably identical with Rowland's solar line 4522'81 rather 

 than with 4522'69, to which he gives a Fe ? origin. 



Notes on Certain p Fe-Solar Lines. 



[1.] A. 4233*33 (4). This solar line was ascribed by Rowland to Mn-Fe in his 

 " Preliminary Table of Solar Wave-lengths." IntVe revised table* the Fe origin 

 is discarded and the sole origin given as Mn. There appears to be, however, no 

 evidence for the line being due to manganese. There is no trace whatever of a 

 line in this position in any of the Kensington photographs of the manganese 

 spectrum, and no such line is given by Hasselbergf in his comprehensive list of 

 manganese arc lines. Although the arc line of iron at the corresponding wave- 

 length is exceedingly weak in many photographs it does not occur at all there is 

 no doubt about there being a prominent line in the spark spectrum. The solar 

 line in question is probably due solely to iron, and is the counterpart of the 

 enhanced line of that metal. In a Cygni the line 4233'33 is quite an outstanding 

 line and one of the very strongest in the spectrum. 



[2.] 4351-93 (5), Cr. This solar line is ascribed by Rowland solely to Cr. 

 Although the chromium line is a moderately strong one it is scarcely likely that its 

 solar equivalent would be as strong as that of the chromium line 4289*89, one of 

 the very strongest lines in the spectrum of that element. The two solar lines 

 mentioned being, however, of the same intensity, in all probability that at 

 A. 4351'93 is partially due to some other element. The strongly enhanced Fe line 

 4351*93 is apparently exactly coincident with the Cr line, and as other similarly 

 enhanced Fe lines occur amongst the Fraunhoferic lines it is probable that the 

 solar line in question is compounded of the iron and chromium lines. 



In a Cygni there is a corresponding well-marked line which, in the light of the 

 complete absence from the stellar spectrum of chromium arc lines, can only be 

 attributed to proto-iron. This is the more likely as the other enhanced lines of 

 iron are so prominent in the a Cygni spectrum. 



This line in stellar spectra has been attributed by Scheiner to the magnesium 

 arc line 4352*08 and on its behaviour with respect to the stellar representative of 

 the characteristic spark line of magnesium 4481-3, he has based conclusions^ on the 

 relative temperatures of the absorbing atmospheres of various stars. Such con- 

 clusions are not trustworthy, as the origin of the line is ob.viously not the same in 

 all stellar spectra. In stars of the solar type the line is probably of a complex 

 origin, Cr 4351*93, Mg 4352*08, and p Fe 4351-93, all being involved. In higher 

 temperatures stars like o Cygni, Sirius, and Rigel there is abundant evidence in 

 favour of a proto-Fe origin and little or none for either chromium or magnesium. 

 Thus, other lines of Cr and Mg, which are similar in intensity and behaviour in 

 their respective spectra to those mentioned above, are all unrepresented in these 

 stellar spectra, whereas all the enhanced Fe lines of similar intensity and 

 behaviour to the line 4351*93 are strongly represented in the same stellar spectra. 



[3.] 4629-52 (6), Ti-Co. It is doubtful whether the Ti and Co lines are collec- 

 tively strong enough to account for the intensity of the solar line. The equally 

 strong Co line 4663'59 only furnishes a solar line of intensity 0, and the stronger 



* ' Ast. Phys. Jour.,' vol. 6, p. 384, 1897. 



t ' Kongl. Sv. Vet. Akademiens Handlingar,' Bd. 30, No. 2. 



J ' Ast. and Ast. Phys.,' vol. 13, p. 560, 



