42 
Variable Stars. 
[January, 
that presented by one or two hundred of such orbits. If the 
variability of Mira is indeed caused by these minute bodies, 
then, undoubtedly, she is surrounded by systems much more 
extensive than the Sun’s, or those of Algol, although we 
may not fairly believe that she is surrounded by sufficient 
quantities to cut off the observed amount of her light. Now 
for our present purpose it matters little whether we regard 
Mira as a very small orb, comparatively, or as situated at a 
vast distance from the Earth. In either case her observed 
brilliancy could be explained. And in either case, if we 
assume that she is surrounded by a large number of dense 
meteor systems, we are provided with an assumption which 
enables us to explain even the variations of her variability. 
We are almost certain that a considerable part of the 
Sun’s heat and light is maintained by the impadt of quan- 
tities of meteors upon his mass. But obviously, unless these 
bodies existed in large quantities, they could not do more 
than assist in maintaining his heat and light. For it would 
be necessary, before they could reach his surface, that they 
should, in some way, be pulled up short in their orbit, so as 
to be forced to fall by attraction upon the Sun’s globe, since 
a body travelling in an orbit would never fall upon the Sun 
unless brought first almost or quite to rest, and there is not 
any way of bringing a moving body to rest save by collision 
with other bodies. From which we easily deduce the faCt 
that the greater the number of meteor systems the greater 
the chance of collisions, and, a priori, the greater the quan- 
tity of matter which would eventually reach the Sun’s 
surface, and, therefore, the stronger the emission of light. 
Furthermore the periodicity with which Mira goes through 
her minor changes could be explained as due to the faCt that 
the density of the matter in each individual meteor ring is 
different in different places, precisely as in the November 
meteor system. In which case we can readily see that the 
amount of matter in her immediate vicinity and suitably 
placed for collision must vary accordingly. 
We have, perhaps, in the rings of Saturn an instance of 
the approach of small bodies to the ruling centre in conse- 
quence of their private encounters. If the observations are 
to be trusted, these rings have been changing in detail and 
increasing in width ever since they were first measured. 
But the strongest evidence in favour of the theory I am 
advocating may be drawn from the changes in the brilliancy 
of the star n Argus. This star is situated in the midst of a 
nebula, and, without doubt, vast quantities of matter must 
be in a continuous state of commotion therein, the effects of 
