422 Variability in Condensing Swarms of Meteorites. [Nov. 21, 



descent gas and vapour in the interspaces will bring about the 

 appearance of the hydrogen lines as bright ones. The thing above all 

 things most capable of doing this in a most transcendental fashion is 

 the invasion of one part of the swarm by another moving with a high 

 velocity. This is exactly what I postulate. The wonderful thing 

 under these circumstances then would be that bright hydrogen shonld 

 not add itself to the bright carbon, not only in bright line stars, but in 

 those the spectra of which consist of mixed nutings, bright carbon 

 representing the radiation."* 



That the bright lines of hydrogen do make their appearance at 

 maximum, in some of the stars at all events, is placed beyond doubt 

 by the recent observations of Mr. Espin at Wolsingham. 



On August 13, 1883, Mr. Espin j noted " a very bright line, appa- 

 rently F," in the spectrum of R Cygni, the maximum of the star 

 occurring on July 19th. 



The spectrum of o Ceti was also observed by Mr. Espinf on 

 October 23rd and 30th, 1888, the maximum of the star occurring on 

 September 28th. Duner's bands from 1 to 10 were seen, and the 

 observer noted that on October 30th, when the star had faded con- 

 siderably, bands 8, 9, and 10 seemed to be broken into two, but he 

 was doubtful whether these interferences were due to bright lines or 

 not. A brilliant line was observed in the violet, which was thought 

 to be h (hydrogen). It is very probable also that bright F was 

 present on this date and caused the second maximum in band No. 9. 



Bright lines of hydrogen and other substances were photographed 

 in the spectrum of Mira by Professor Pickering in November, 1886, 

 the maximum occurring on November 14th. 



Mr. Maunder J observed bright hydrogen (G) in the spectrum of 

 Mira on October 5th, 1888, but on December 1st it was not recorded. 



Mr. Espin has also announced in a recent circular (April 2nd, 

 1889) that there are bright lines in the spectra of R Leonis and 

 R Hydrae. He states that " the spectra of R Leonis and R Hydras 

 contain bright (hydrogen ?) lines, first seen on February 25th. 

 Observations confirmed, through the kindness of Mr. Common, by 

 Mr. Taylor, at Ealing, who sees two in R Leonis and one in 

 R Hydrae." Both these stars were near their maxima at the time 

 of observation, that of R Leonis occurring on March 23rd, and that 

 of R Hydrae on February 17th. 



[Another circular (October 3, 1889) states that " Bright lines 

 were seen in the spectrum of R Andromedae on September 25th, the 

 F line being very bright." The maximum occurred on July 25th. — 

 November 1, 1889.] 



* Bakerian Lecture, p. 83. 



f 1 Ast. Soe. Monthly Notices,' vol. 49, p. 18. 



X ' Ast. Soc. Monthly Notices,' vol. 49, p. 304. 



