134 Sir Norman Lockyer. 



Magnitude, 



The magnitude has been estimated on sixteen evenings. These seem 

 to afford sufficient evidence that since the beginning of May the star 

 has decreased in magnitude from about 5 -7 to 6'7 ; further, the short 

 variations previously recorded apparently no longer exist, as the esti- 

 mated magnitudes on eleven nights since the end of August only vary 

 between 6'5 and 6 '8. 



Photographs of the region about the Nova were taken with the 

 6-inch Dallmeyer doublet on the evenings of August 25 and September 

 11, 12, and 18. From these it has been ascertained that its magnitude 

 relatively to those of the surrounding stars is greater photographically 

 than visually. 



J'i.oml Spectrum. 



The spectrum has been observed with a McClean direct-vision 

 spectroscope on the evenings of August 8, 13, 17, 20, 22, 24, and 

 September 11, 12, 18. The line in the position of the chief nebular 

 line at A 5007 has always been noted as being the strongest, lift and 

 the line at A 4959 being also present, but comparatively much weaker. 

 Fairly bright lines near A 472 and the region of Hy have also been 

 recorded. Traces of a few lines less refrangible than A 5007 have been 

 glimpsed, but no determinations of their wave-lengths have been 

 made. No lines have been observed in the yellow or red regions of the 

 spectrum. 



Photograph ic Spectrum. 



Photographs have been taken on the evenings of August 9, 15, 17, 

 21, 22, 23, 24, 26, September 3, 5, 9, 10, 11, 12, 18, 21, 23, 25, 2G, 

 with the 9-inch prismatic reflector, the Nova being now far too faint 

 for the utilisation of the 6-inch objective prism, and, until quite 

 recently, in such a position as to make the 30-inch reflector unavail- 

 able. These photographs show little or no variation amongst themselves 

 either in the number, position, or relative intensities of the lines. The 

 scale of the photographs is such that the distance between Hft and He 

 is about 0'9 cm. The wave-lengths of the lines have been determined 

 from the best photograph (August 26) by means of an interpolation 

 curve. The presence in the Nova spectrum of some of the hydrogen 

 lines and the helium line A 4471 was established by direct comparison 

 with the spectra of other stars photographed with the same instrument. 

 These lines were used, together with the 5007 line (the identity of 

 which with the strongest nebula line was assumed), as fiducial lines for 

 the construction of the interpolation curve. The remaining lines were 

 then measured and their wave-lengths read off from the curve. The 

 intensities of the lines as they appear on the plate were also noted. 



