1901 - 5 .] On Prof. Seeligers Theory of Temporary Stars. 519 
star. In other words, as a consequence of the collision, the star 
becomes permanently surrounded with a ring of luminous meteoric 
matter, revolving in ellipses with eccentricities probably ranging 
from zero to unity. The transformation of molar into molecular 
energy must lead to incandescence, which will be in proportion to 
the amount of converted energy. But this latter is evidently 
greatest in the case of circular orbits, because here the reduction 
of Y from its original hyperbolic value is most considerable. Hence 
the brightest parts of the ring are composed of particles moving 
round the star in ellipses of small eccentricities. 
Now, we cannot avoid the conclusion that the kind of collision 
here described must occur in the case of a new star, provided that 
Seeliger’s fundamental assumptions be true. I can imagine only 
one exceptional instance to which the above reasoning would seem 
inapplicable, viz., that the cloud particles move towards the star 
exactly in the direction of its centre, but I think the scarcity of 
such a phenomenon will at once be admitted. The most probable 
assumption is that of a more or less one-sided collision, such as is 
represented in fig. 1. Granting the reasoning so far, we conclude 
that after the catastrophe the star is surrounded by radiating 
nebular (meteoric) matter revolving in closed elliptical paths 
round the star’s centre as focus, the brightest nebular particles 
describing orbits of small eccentricities. 
The result in this general form is sufficient to assist us later on 
in the interpretation of the Nova spectrum. With regard to the 
constituency of the luminous ring, the most general assumption 
is that it consists of a mixture of bodies in all three states of 
aggregation — solid, liquid, and gaseous. But owing to their high 
power of radiation, the liquids and solids will cool down much 
sooner than the gases, so that in a more advanced state the spectral 
appearance of the ring will be that of an incandescent gaseous body 
emitting a line spectrum. 
The problem, in its main principle, is seen to be closely related 
to Encke’s celebrated theory of a resisting medium. A force 
acting near perihelion in the direction of the tangent against the 
orbital motion of a body causes a progressive (secular) diminution 
of the major axis and eccentricity of the orbit, and therefore tends 
to incorporate the body into the system of the attracting centre, 
