2 Proceedings of the Royal Society of Victoria. 



theory which he favours most ; iny object, therefore, in writing 

 this paper is to discuss the work done on the star at different 

 observatories during last year, in order to see what light it 

 throws, taken as a whole, on the claims of the rival theories. 



2.— Early History of the Outbreak. 



Nova Persei was the first of the temporaries to have its 

 spectrum examined l)efore and during, as well as after, its epoch 

 ■of maximum luminosity. Discovered by Anderson on 21st Feb- 

 ruary, its spectruni was photographed by Pickering^ at Harvard 

 on the 22nd ; by Vogel" at Potsdam, as well as at Harvard on the 

 23rd — the night of the maximum, when the star for a short time 

 held the proud pre-eminence of " the brightest star in the north- 

 ern heavens " — and at the Lick^ and Yerkes* observatories, as 

 well as at Harvard on the 24th ; all other photographs known to 

 me are of later date. 



These earliest photographs prove that on 22nd February the 

 spectrum was that characteristic of the " Orion group " of stars ; 

 it showed a continuous spectrum crossed by a comparatively 

 small number of fine dark lines, practically undisplaced from 

 their normal positions, among which those of hydrogen and the 

 magnesium line X4481 were decidedly the most prominent ; 

 Pickering records these as "bright on the less refrangible edge;" 

 there was no sign of the typical spectrum. One the next 

 night Pickering found K present ; otherwise the spectrum was 

 "apparently unaltered," but the star was obscured by clouds, 

 and the photograph faint. On the same night, however — and, 

 judging from the difference in longitude of the two observatories, 

 some time previous to Pickering's photograph — Vogel obtained 

 two plates, showing a bright continuous spectrum, crossed by 

 broad hazy hydrogen absorptions,^ and by a number of fine 

 dark lines, H and K being conspicuous among the latter, but he 



1 Ap. J., xiii., pp. 170, 232. 



2 Ap. J., xiii., p. 217. 



3 Ap. J., xiv., p. 269. 



4 Ap. J., xiii., p. 238. 



5 Possiblj' the cloudy weather prevented these from showiiij,' on Pickering's second 

 plate. 



