88 Mr. J. N. Lockyer. On the Classification [Apr. 12, 



stars of short period, which obviously are not here in question, there 

 can be no reasonable doubt, that the eclipse explanation is a valid 

 cue ; but in cases such as we are now considering, when we may say 

 that the ordinary period is a year, this explanation is as much out of 

 place on account of period, as are such suggested causes as stellar 

 rotation and varying amount of spotted area on a stellar surface, on 

 account of range. 



We are driven, then, to consider a condition of things in which 

 the minimum represents the constant condition, and the maximum a 

 condition imposed by some cause which produces an excess of light ; 

 so far as I know the only explanation on such a basis as this that has 

 been previously offered is the one we owe to Newton, who suggested 

 such stellar variability as that we are now considering was due to 

 conflagrations brought about at the maximum by the appulse of 

 comets. 



Row the Difficulty of Regular Variability on Newton's View is got over 



in mine. 



It will have been noticed that the suggestion put forward by 

 myself is obviously very near akin to the one pat forward by Newton, 

 and no doubt his would have been more thoroughly considered than 

 it has been hitherto, if for a moment the true nature of the special 

 class of bodies we are now considering had been en evidence. We 

 know that some of them at their minimum put on a special ap- 

 pearance, of their own in that haziness to which I have before 

 referred as having been observed by Mr. Hind. My researches show 

 that they are probably nebulous r if indeed they are not all of them 

 planetary nebulae in a further stage of condensation, and such a 

 disturbance as the one I have suggested would be certain to be com- 

 petent to increase the luminous radiations of such a congeries to the 

 extent indicated. 



Some writers have* objected to Newton's hypothesis on the ground 

 that such a conflagration as he pictured could not occur periodically ; 

 but this objection I imagine chiefly depended upon the idea that the 

 conflagration brought about by one impact of this kind would be quite 

 sufficient to destroy one or both bodies, and thus put an end to any 

 possibilities of rhythmically recurrent action. It was understood that 

 the body conflagrated was solid like our earth. However valid this 

 objection might be as urged against Newton's view, it cannot apply to 

 mine, because in such a swarm as I have suggested, an increase of 

 light to the extent required might easily be produced by the incan- 

 descence of a few hundred tons of meteorites. 



I have already referred to the fact that the initial species of the stars 

 we are now consiuering have spectra almost cometary, and this leads 

 us to the view, that we may have among them in some cases swarms 



