1904 - 5 .] On Prof. Seeligers Theory of Temporary Stars. 535 
differ essentially from that with which we are at present 
familiar. 
The object of this short transgression upon the field of molecular 
physics is to show that the reality of enormous velocities in 
expanding gases, such as we see in solar eruptions, cannot well he 
refuted by a reasoning based on conceptions of molecular matter 
in w T hich electric agencies are ignored. There is no cogent reason, 
either on the part of theory or observation, which would force us 
to pronounce the displacements of gaseous matter on the sun as 
£ appearances ’ only. Hence, from the point of view here 
advocated, the stupendous rate of expansion of the ‘ atmosphere ’ 
of a new star may also be brought within the range of mental 
comprehension. It must be considered as a decided advantage of 
this theory that the asserted displacements of the spectral lines by 
motions of expanding gases in the line of sight are phenomena 
clearly noticeable in solar spectroscopic observations, whereas 
we have no recorded instance in cosmic evolution which might 
support, in a similar convincing manner, the assumption of 
exorbitant pressure or of abnormal refraction. 
We will now turn to the quantitative test of the displacements 
caused by the rotating ring. The motions in the line of sight are 
here, according to the theory, of the order of the orbital velocities 
of bodies revolving round the nucleus of the attracting star near 
its surface. If we assume the star of the mass and dimensions of 
our sun, and if we remember that the brightest part of the ring 
is formed by substance revolving in circular orbits whose radius 
is practically that of the star, we find displacements of the two 
maxima in the bands corresponding to approximately 4-500 km. 
per second, which would be equivalent to a distance of about 
11-14 tenth-metres between the two maxima. These figures are 
in close agreement with the observations which showed a distance 
of about 15 tenth-metres. Hence there is no difficulty in com- 
prehending these displacements, and therefore also the enormous 
breadth of the Nova lines, on the assumption that they are caused 
by the orbital motions of particles revolving in the immediate 
neighbourhood of the star’s surface. 
It will doubtless be noticed that the theory requires no assump- 
tion as regards the magnitude of the original relative motion 
