the distance of Nova Cygni was too great to be measured by
observations of this kind.

It is certain that if Nova Cygni had been one of the nearest stars these
observations would not have been abortive. We are therefore entitled to
believe that Nova Cygni must be at least 20,000,000,000,000 miles from
the solar system; and the suggestion that the brilliant outburst was of
small dimensions must, it seems, be abandoned. The intrinsic brightness
of Nova Cygni, when at its best, cannot have been greatly if at all
inferior to the brilliancy of our sun himself. If the sun were withdrawn
from us to the distance of Nova Cygni, it would seemingly have dwindled
down to an object not more brilliant than the variable star. How the
lustre of such a stupendous object declined so rapidly remains,
therefore, a mystery not easy to explain. Have we not said that the
outbreak of brilliancy in this star occurred between the 20th and the
24th of November, 1876? It would be more correct to say that the tidings
of that outbreak reached our system at the time referred to. The real
outbreak must have taken place at least three years previously. Indeed,
at the time that the star excited such commotion in the astronomical
world here, it had already relapsed again into insignificance.

In connection with the subject of the present chapter we have to
consider a great problem which was proposed by Sir William Herschel. He
saw that the stars were animated by proper motion; he saw also that the
sun is a star, one of the countless host of heaven, and he was therefore
led to propound the stupendous question as to whether the sun, like the
other stars which are its peers, was also in motion. Consider all that
this great question involves. The sun has around it a retinue of
planets and their attendant satellites, the comets, and a host of
smaller bodies. The question is, whether all this superb system is
revolving around the sun _at rest_ in the middle, or whether the whole
system--sun, planets, and all--is not moving on bodily through space.

Herschel was the first to solve this noble problem; he discovered that
our sun and the splendid retinue by which it is attended are moving in
space. He not only discovered this, but he ascertained the direction in
which the system was moving, as well as the approximate velocity with
which that movement was probably performed. It has been shown that the
sun and his system is now hastening towards a point of the hea