NEW STAR IN THE CONSTELLATION SWAN, 61 



Tycho Brahe, struck with the suddenness of the appearance of the 

 star of 1572, and its position on the edge of the Milky- Way, offered a 

 bold hypothesis which is now abandoned. He believed in a creation 

 or at least in the spontaneous incandescence of the nebulous matter 

 of which he supposed the Milky-Way to be composed : when the new 

 star vanished, the place it had occupied was void, or at least Brahe 

 saw, in the absence of nebulosity at that spot, the result of the con- 

 densation of the matter the combustion of which had produced an 

 appearance resembling a star. Humboldt justly compares this view, 

 w^hich at all events was an ingenious one, with the views held by W. 

 Herschel as to the transformation of nebulae into stellar masses. In 

 Tycho Brahe's time it was not known that the light of the Milky- 

 Way results from the aggregation of an indefinite number' of stars, 

 or stellar masses, and that it is within this immense agglomeration 

 and in its vicinity that tlie nebula? properly so called are rarest. 



Besides, it has been proved that the stars known as " new " stars 

 are anything but new. In the spot where the star of 0])hiuchus made 

 its appearance in 1848, there had previously been a star, noted by 

 Lalande in Fortin's " Atlas Celeste " as a vanislied star. So, too, the 

 new star which appeared in May, 1866, in the Corona Borealis, and 

 which at the start reached the second magnitude, had been already set 

 down in catalogues as a star of tlie ninth magnitude ; it still possesses 

 the same lustre it had before it underwent, during the six months of its 

 apparition, the extraordinary augmentation which attracts to it the 

 attention of astronomers. Hence astronomers no longer believe in the 

 creation or in the destruction of these stars. Before the sudden in- 

 candescence which makes them visible, they occupied the same places, 

 and there they still remain after their more or less perfect extinction. 

 It remains to inquire into the physical causes which produce these 

 variations of lustre.' 



Spectrum analysis has provided the first positive elements for the 

 solution of this problem. As late as the year 1848 this method was 

 as yet unknown ; but when in 1866 the variable star of the Northern 

 Crown [Corona Borealis) appeared, spectrum analysis was already so 

 developed as to be profitably applied to the observation of it. The 

 results obtained by Huggins and Miller in these researches were as 

 follows : 



' It is worth while to observe the ease with which these knotty questions are dis- 

 posed of by persons who are wont to invoke supernatural agencies. Here is an instance 

 dating from the seventeenth century, but similar instances may be found in our own 

 time : Father Riccioli, as an explanation of the appearance of secondary stars, suggested 

 the idea that some stars are luminous on one side; and whenever God would "exhibit to 

 men some extraordinary sign, he turns toward them the luminous side (previously turned 

 away from the earth) by causing the star to revolve about suddenly, either by the agency 

 of some intelligent being, or in virtue of some faculty inherent in the star itself; then, 

 by making another similar revolution, it suddenly vanishes, or pales gradually, like the 

 moon iu its phases." The explanation offered by the learned Jesuit is both ingenious 

 and convenient. But, unfortunately, astronomers nowadays are not satisfied with it. 



