624 Mr. William Huggins on the Neio Star in Auriga. [May 13, 



one component gives bright lines, and the other dark lines of absorp- 

 tion. We must, however, assume a similar chemical nature for both 

 bodies, and that they existed under conditions sufficiently similar for 

 equivalent dark and bright lines to appear in their respective spectra. 



We have no knowledge of the distance of the Nova, but the 

 assumption is not an improbable one that its distance may be of the 

 same order of greatness as that of the Nova of 1876, for which Sir 

 Robert Ball failed to detect any parallax. In this case, the light- 

 emission suddenly set up, certainly within two days and possibly 

 within a few hours, was probably much greater than that of our sun ; 

 yet within some fifty days after it had been discovered, at the end of 

 January, its light fell to about l/300th part, and in some three 

 months to nearly the 1/ 10,000th part. As long as its spectrum 

 could be observed the chief lines remained without material altera- 

 tion of relative brightness. Under what conditions could we suppose 

 the sun to cool down sufficiently for its light to decrease to a similar 

 extent in so short a time, and unaccompanied with the incoming of 

 very material changes in its spectrum. It is scarcely conceivable that 

 we can have to do with the conversion of gravitational energy into 

 light and heat. On the theory we have ventured to suggest, the 

 rapid calming down, after some swayings to and fro of the tidal 

 disturbances, and the closing in again of the outer and cooler gases, 

 together with the want of transparency which might come in under 

 such circumstances, as the bodies separated ; might account reason- 

 ably for the very rapid and at first curiously fluctuating waning of the 

 Nova, and also for the observed absence of change in its spectrum. 



I may, perhaps, be permitted to remark that the view suggested 

 by Dr. William Allen Miller and myself, in the case of the Nova of 

 1866, was essentially similar, in so far as we ascribed it to erupted 

 gases. The great suddenness of the outburst of that star, within 

 a few hours probably, and the rapid waning from the 3'6 magni- 

 tude to the 8'1 magnitude in nine days, induced us to throw out 

 the additional suggestion that possibly chemical actions between 

 the erupted gases and the outer atmosphere of the star may have 

 contributed to its sudden and transient splendour, a view which, 

 though not impossible, I should not now, with our present know- 

 ledge of the light changes of stars, be disposed to suggest. 



The subject is necessarily obscure, but we must not on this account 

 feebly relinquish the hope of conquest. The words of a great Seer 

 may well be taken as the watchword of the Astronomer : — 



..." Fervent love, 

 And lively hope, with violence assail 

 The kingdom of the heav'us, and overcome " 

 If * » 



[W. H.] 



