1893.J Bands in the present Spectrum of Nova Aurigce. 35 



We have endeavoured to represent in the diagram as truthfully 

 as we can the best views we obtained of this group ; but during one or 

 two exceptional moments of good seeing we thought that we glimpsed 

 finer bright lines in the spaces between. Indeed, the group may con- 

 sist of a close grouping of bright lines. 



For the same reasons, fewer measures were attempted of this group, 

 and its position was less accurately determined, but neither the con- 

 stitution of the group as represented in the diagram nor its position 

 can, we think, be much in error. 



We were also unable to work upon the bright line in the orange, 

 and to do more than satisfy ourselves, by a direct comparison, that 

 the line about F was really the hydrogen line in that region. 



General Conclusions. 



It need scarcely be said that no contrast could well be more striking 

 than that which these extended groups of lines form with the two 

 narrow and defined lines in the spectrum of the Great Nebula in Orion. 



It is difficult to suppose that we have to do with the same substance 

 or substances, whatever they may be, which produce the nebular lines, 

 even if we imagine very different conditions of temperature, or even 

 allotropic conditions. 



In the laboratory, allotropic changes are not usually accompanied 

 by new groups, or lines at the positions of the characteristic lines of 

 the substances in their original state. 



We wish to speak at present with great reserve, as our knowledge 

 of the Nova is very incomplete, but we do not regard the circumstance 

 that the two groups of lines above described fall near the positions of 

 the two principal nebular lines as sufficient to show any connexion 

 between the present physical state of the Nova and that of a nebula, 

 of the class which gives these lines. 



Influenced by the analogy between some of the changes in the 

 spectrum of the Nova and those which are associated in the spectrum 

 of ft Lyrae with the variation of its light, and also by other reasons 

 which we pointed out in our former communication, we are still 

 strongly inclined to take the same view which we there ventured to 

 suggest, namely, that in the outburst of the Nova we have not to do 

 mainly with cold matter raised suddenly to a high temperature by a. 

 collision of any form bat rather, for the most part, as was suggested 

 by Dr. Miller and myself in 1866 in the case of the first temporary 

 star examined with the spectroscope, with an outburst of existing- 

 hot matter from the interior of the star or stars ; indeed, with phe- 

 nomena broadly similar to, but on an immensely grander scale than 

 those with which we are familiar in the periodic greater and lesser 

 disturbances of the Sun's surface. 



D 2 



