The Fiscian Stars. 



137 



successive species, which is exactly what we should expect if these 

 species truly represent the effect of gradual cooling. 



Variability of Piscian Stars, 



Of the fifty-five stars in Duner's list, ten exhibit fluctuations in 

 brilliancy. 



On the whole the light changes are not so great as in the stars of 

 Group II, and the periods tend to greater length. 



As to the cause of variability, the increase of light at maximum 

 may be due, as I suggested in 1890,* to the light added by bodies 

 of a cometary character when they reach periastron, the increase of 

 luminosity being produced by tidal action, as in the case of comets in 

 our own solar system. If there be any truth in this idea, it seems 

 probable that the added light of the comet at maximum, which would 

 give a spectrum consisting of bright carbon flutings, would produce a 

 paling of the carbon absorption flutings. 



As in the variables of the Antarian group, which are uncondensed 

 swarms, and where, on the meteoritic hypothesis, the increased light 

 at maximum is produced by the collision of a revolving swarm at 

 periastron, irregularity is a natural consequence of the revolution qf 

 more than one secondary body. 



Addendum. 



: Recent Observations, 



The Kensington observations were made chiefly during 1894 and 

 1895, with special reference to the lines involved. The stars selected 

 for observation were 132 Schjellerup, 152 Schjellerup, 115 Schjellerup, 

 and 19 Piscium. The 3-foot reflector was used. In addition to the 

 carbon bands, numerous lines were seen without much difficulty, but 

 only the more prominent ones could be satisfactorily measured. 

 Among the lines recorded in 132 Schj. were H/5, the E line of iron at 

 5269, and a group of lines near A 5380. In 115 Schjellerup addi- 

 tional lines were measured near 5005, 5762, and 5429, and the presence 

 of was again determined by comparison with a hydrogen vacuum 

 tube. In 19 Piscium numerous lines were observed, among them being 

 D and F. No suspicion of bright lines was entertained during these 

 observations. Attempts to photograph the spectra were not sufficiently 

 successful to help matters. 



In 1898, Dr. McClean published photographs of the spectra of 

 19 Piscium and 152 Schjellerup,! showing that these stars have a line 

 spectrum similar to a Tauri, in addition to the well-marked bands 



* ' Nature,' vol. 42, pp. 419, 548. 



t ' Pkil. Trans./ rol. 191, A, p. 131, plate 14. 



