366 Proceedings of Royal Society of Edinburgh. [sess. 
501 and 486, and thus would seem to agree with those of the two 
principal nebula lines.* The positions of these features were 
measured as satisfactorily as their faintness permitted. 
Several of the dark lines I was able to confirm, hut thickening 
haze prevented further observation. On this night Mr Heath 
secured a photograph of the star with the 24-inch reflecting tele- 
scope through shifting clouds. The night of the 23rd was unfor- 
tunately overcast, except for a very short interval at about eight 
o’clock, when Dr Halm and Mr Clark saw the Nova and esti- 
mated its brightness, which was found to exceed that of Capella 
by a fifth of a magnitude. An attempt at viewing the spectrum 
with the 15-inch refractor led to no result. 
The sky was completely overcast on the 24th, 25th, and 26th. 
On the 27th the weather was more favourable, although observa- 
tions could only be made through rifts in the clouds. The whole 
character of the spectrum had, in the interval, undergone a pro- 
found change, and now resembled indeed that of Nova Aurigse 
when at its greatest brilliancy. Besides the bright bands suspected 
on the 22nd, which had now’ increased so much in brightness as 
to become the most prominent feature in the spectrum, the C-line 
of hydrogen had blazed out with great brilliancy. This line had 
been specially looked for on the 22nd, but no trace of it could 
then be distinguished. Nearly all the bright bands were of con- 
siderable width, being, in fact, in general not less than three 
times the width of the slit used. It required no considerable 
optical means to bring out the special characteristics of the Nova 
type, for the whole spectrum was beautifully shown on applying 
a tiny direct vision prism and cylindrical lens to the eye-piece of 
the finder, wdiich has an aperture of only 3f inches. 
Owing to the repairs of the dome, now in progress, the auto- 
matic driving of the telescope was to some extent deranged. In 
spite of these untoward circumstances, Dr Halm and I succeeded 
in securing a fair number of measures of the principal spectroscopic 
features. 
* Note added March 15. — While the band at 486 /x/jl is undoubtedly due 
to hydrogen, which is also present in the spectrum of the nebulae, that at 501 
jxjx does not appear, as later measurements showed, to coincide with the chief 
nebula line at 5007, but is probably identical with the chromospheric line 
.501 ‘8 due to iron. 
