368 
Proceedings of Royal Society of Edinburgh. [sess. 
been possible to determine the wave-lengths of the lines shown on 
these plates, but the general character of the spectrum seems to 
agree with that of the visual part. 
In the Times of March 1st Miss Agnes M. Clerke propounded 
the hypothesis that the broadening of the lines in the spectrum of 
the new star might be due to the influence of a powerful magnetic 
field, and that in this case their light would be polarised, so to 
speak, in “ sections,” thus affording an instance of the well-known 
“ Zeeman phenomenon/’ At the same time Miss Clerke indicated 
how the question might be at once decided with the help of a 
Nicol prism. Last night afforded a singularly favourable chance 
for making this interesting experiment. Accordingly, at a time 
when the sky was perfectly clear, and the spectrum was conse- 
quently seen to the best advantage, the chief lines were carefully 
examined with a square-ended polarising prism by Dr Halm and 
myself. Ho trace of polarisation was, however, visible; on the 
contrary, the bright lines could be clearly seen of their full width 
in all positions of the prism. To whatever cause, therefore, the 
extreme width of these lines may be due, it is not to the one so 
ingeniously suggested by Miss Clerke. 
Regarding the brightness of the star, the following notes may be 
of general interest : — 
Feb. 19. — Prof. Pickering photographed that part of the 
heavens without obtaining a trace of the star, which he considers 
must therefore have been fainter than 11th magn. 
m. 
Feb. 21, 
14 h 40 m 
M.T.Gr., 
2*7 Anderson. 
22 
6 
58 
55 
0*7 Copeland. 
53 
8 
10 
55 
0-5 „ 
23, 
8 
10 
55 
0*0 Halm and Clark. 
27, 
11 
15 
55 
1*6 Copeland; decided yellow. 
Mar. 1 , 
11 
0 
55 
2*3 „ 
2, 
11 
40 
55 
2*2 „ 
3, 
12 
25 
55 
2*0 ,, orange red. 
From the 19th to the 23rd the star must have increased in 
brightness at least 25,000 times (25,120). 
On the other hand, in the interval between the 23rd of February 
