224 Prof. A. *Fowler. The Spectra of Antarian Stars [Feb. 18, 



by Duner. The association of vanadium with titanium in the spectra 

 of sun spots suggested that they might be due to the former element, 

 but this does not appear to be the case. The strongest fluting of 

 vanadium is near 5472, and there is no certain evidence to show the 

 presence of this fluting in the Antarian type of spectrum. 



The evidence for titanium in the case of the remaining flutings, 

 however, is enormously strengthened by a discussion of their structure 

 and by extending the comparison further into the violet. Photographs 

 of the stellar spectra, especially those of o Ceti and a Herculis, show 

 that some of the principal flutings are composite, Duner's band 10, for 

 example, containing, according to Sidgreaves, four distinct flutings 

 separated by intervals of about 44 tenth-metres, each of which is 

 weaker than the one which precedes it on the more refrangible side. 

 A precisely similar structure is found in the case of the titanium 

 flutings, and a comparison of wave-lengths indicates that the various 

 components occupy the same positions as those in the stars, so far as 

 the available measurements permit the test to be applied. For this 

 comparison (Table II) the wave-lengths derived from photographs by 

 Father Sidgreaves and Mr. Stebbings are utilised. The relation may 

 also be gathered by inspection of the reproductions of the photographs 

 given in Plate 6, that of o Ceti having been very kindly placed at my 

 disposal by Father Sidgreaves. Not all the details of the negatives, 

 however, can be brought out in the reproductions, and the relative 

 dispersions are not exactly the same. 



It will be seen from the table that the details of the titanium flutings 

 are reproduced with remarkable fidelity in the stellar spectra, and more 

 especially in o Ceti. In the latter spectrum the number of flutings 

 recorded is slightly greater than in the case of titanium, but it is by no 

 means certain that every detail of the titanium spectrum has yet been 

 photographed. It is possible also that some of the features described 

 as flutings in the stellar spectrum may be groups of lines, and 

 in at least one instance (4437) a fluting has been classed as a "wide 

 line." 



The points of difference are very slight, and are mostly in the less re- 

 frangible part of the spectrum, where the reductions of the stellar spectra 

 present the greatest difficulty. There is a peculiar displacement of the 

 fluting 4848 to X 4842 in the spectrum of o Ceti, which may possibly 

 be due to the superposition of a fluting or group of lines of undeter- 

 mined origin ; or, it may be that the feeble maximum observed at 

 4842 in titanium is strong enough in this spectrum to account for the 

 apparent shift. There is also some uncertainty in connection with the 

 complicated groups of flutings and lines extending from 5598 to D, 

 which need further investigation in the stellar spectra with instruments 

 of greater dispersion. 



The general agreement is nevertheless such as to leave no reason- 



