Further Observations on Nova T 



ersei 



145 



The best star for this purpose is cc Cygni, but unfortunately no good 

 photograph has been obtained at Kensington of the green portion of 

 the spectrum of that star. The star most nearly approaching a Cygni 

 in relation to enhanced lines is cc Canis Majoris, which in the 

 Kensington classification has been placed nearly on a level with the 

 former star, but on the descending side of the temperature curve. In 

 the spectrum of this star the enhanced lines of iron XX 4924*11, 



spectrum has been directly compared with that of Nova Persei taken 

 with the same instrument, and the fact that all the lines apparently 

 coincide, affords good evidence that the connection is a real one, and 

 that the first four strong Nova lines beyond F on the less refrangible 

 side are the representatives of the enhanced lines of iron. These are 

 the only enhanced lines which occur in that part of the iron spectrum, 

 with the exception of a weak one at X 5276*17. There is only a trace 

 of this line in the spectra of either the Nova or cc Canis Majoris which 

 have been compared. In the spectra of the Nova obtained with lower 

 dispersion, However, a line is distinctly shown in this position, though 

 it is considerably weaker than the four lines previously mentioned. 



The absence of the strong lines which are familiar in the arc spec- 

 trum, and in the ordinary spark spectrum in this region, is to be 

 ascribed to higher temperature; experiments which are in progress 

 show that under certain conditions, the two lines X 5018*6 and 

 A 5169 are by far the strongest lines in the spectrum of iron between 

 X 500 and D, while that at X 4924*1 is distinctly stronger than any of 

 the well-known group of four arc lines in which it falls. 



The published wave-lengths of the lines of Nova Aurigae show that 

 the same lines were present in that star. Further investigations of 

 the spectrum of Nova Aurigae have strengthened the conclusion that 

 most of the lines, after we pass from those of hydrogen, are enhanced 

 lines of a comparatively small number of metals. 



When the inquiry is extended into the region more refrangible 

 than H/3, the evidence in favour of the similarity of the spectra of the 

 two Novae with that of cc Cygni is not so conclusive, because of the 

 greater breadth of the lines (since the spectra have been obtained by 

 the use of prisms) and because of the fact that in this region the 

 enhanced lines of iron frequently occur in groups. 



In the region between HS and Hy, however, there is a well marked 

 enhanced line of iron at X 4233*3 and also two doubles at XX 4173*7, 

 4179*0, and XX 4*296*7, 4303*3, and a comparison of a Cygni with 

 Nova Persei indicates that these fall on broad bright bands of the 

 Nova spectrum. 



It is not claimed that all the enhanced lines which appear in the 

 spectrum of cc Cygni are represented in that of Nova Auriga?. There 



occur as well-marked lines. This 



