32 Dr. and Mrs. Huggins. On the Bright [June 8, 



4940 4950 4960 4970 49^0 49QO 5000 5010 5020 5030 5040 



I. 



Rowland's Scale Observed FeF6 th -26* 1593 



were attempted tlie sky was not clear enough from thin haze for the 

 resolution of the more difficult features of the spectrum of a star of 

 between the 9th and 10th magnitude. 



Still, notwithstanding the comparatively incomplete state of our 

 observations, which we greatly regret, we do not hesitate to consider 

 them of sufficient importance, bearing as they do upon so remarkable 

 a phenomenon as would be the change of a star into a nebula, to 

 justify us in communicating them to the R-oyal Society. 



The spectroscope is provided with a 4-inch Rowland grating by 

 Brashear, and a prism of dense flint of 27, silvered on one face, 

 which can take the place of the grating in the grating box. 



As we have already stated, the observation of the Nova with this 

 prism showed the bright " lines " broad and irregularly bright, and 

 raised the suspicion in our minds that they were probably groups. 

 They were observed more or less successfully with the grating, 

 usually with an eye-piece magnify ing -23 diameters, on February 8, 

 10, 11, 16, 17, and 26. 



1. Brighter Group near the Position of the Principal Nebular Line. 



The separate results of our more favourable observations of this 

 group on the different nights are put together in the accompanying 

 diagram. In addition, however, to the details drawn in the diagram, 

 at several very favourable moments of seeing, we had distinct and 

 undoubted glimpses of finer lines in the spaces between the brighter 

 ones, of which some only are given in the diagram. For this reason 

 the diagram must be regarded as an incomplete representation of the 

 group, though showing accurately its main features and general 

 character. 



The group, as shown in the diagram, extends through a little 

 more than 15 tenth-metres, and consists of lines more or less bright 

 upon a feebly luminous background, which can be traced to some 

 distance beyond the lines at both ends of the group. The more 

 prominent features are : two lines, the brightest in the group and 

 about equally bright but the more refrangible one rather the 



