1900-1901.] Note on the New Star in Perseus. 367 
Somewhat similar observations were made on March 1st, but 
the impression was gained that the dispersion employed was too 
great for the star’s diminished light. Accordingly a 30° prism of 
very transparent flint glass by Salleron was adapted to the spec- 
troscope. 
On resuming work on the 3rd, under favourable atmospheric 
conditions, this change in the apparatus told with full effect. All 
the larger bright lines were well defined, each one with an 
attendant deep black line on the more refrangible side. 
This very favourable night afforded a large number of satis- 
factory measures, which still await final reduction. The chief 
results may, however, to some extent be summarised as follows : 
The spectrum seems to be due to two media, one of which emits 
light of a limited number of definite wave-lengths, and must there- 
fore be considered as gaseous. The continuous background may 
reasonably be attributed to matter of a liquid or solid constitution. 
The dark lines are then the effect of absorption on the part of the 
same kind of gaseous matter that yields the bright spectrum, only 
with this difference, that the absorbent medium must be of lower 
temperature than the body producing the continuous spectrum, 
and that it is being carried towards us at a very high velocity. It 
is not at all necessary that this absorbent layer should be of great 
thickness, provided it is of sufficient density. The relative differ- 
ence of velocity of the two bodies is quite stupendous, the reduc- 
tion of the observations so far yielding the enormous value of 800 
miles per second. It is certainly remarkable that this Nova 
should show a displacement of nearly the same amount and towards 
the same side as Nova Aurigae. It is not altogether inconceivable, 
however, that the two stars may have something in common as 
regards their origin, as they are both in the Milky Way, and not 
more than 30° apart. 
The accompanying drawing made by Dr Halm, which was shown 
at the meeting, represents the spectrum as seen in our instrument 
on March 3rd. The intensity curve is based on estimates of 
brightness of the bands made at the same time. 
A number of photographs of the violet part of the spectrum 
have been secured by Mr Heath, using an object glass prism in 
front of the 6*3 inch equatorial. Unfortunately it has not yet 
