would most likely be a grazing one instead of a direct front-to-front
encounter. But even a close approach, without any actual collision,
would probably prove disastrous, owing to the tidal influence of each
of the bodies on the other. Suns, in consequence of their enormous
masses and dimensions and the peculiarities of their constitution, are
exceedingly dangerous to one another at close quarters. Propinquity
awakes in them a mutually destructive tendency. Consisting of matter
in the gaseous, or perhaps, in some cases, liquid, state, their tidal
pull upon each other if brought close together might burst them
asunder, and the photospheric envelope being destroyed the internal
incandescent mass would gush out, bringing fiery death to any planets
that were revolving near. Without regard to the resulting disturbance
of the earth's orbit, the close approach of a great star to the sun
would be in the highest degree perilous to us. But this is a danger
which may properly be regarded as indefinitely remote, since, at our
present location in space, we are certainly far from every star except
the sun, and we may feel confident that no great invisible body is
near, for if there were one we should be aware of its presence from
the effects of its attraction. As to dark nebulæ which may possibly
lie in the track that the solar system is pursuing at the rate of
375,000,000 miles per year, that is another question -- and they, too,
could be dangerous!

This brings us directly back to ``Nova Persei,'' for among the many
suggestions offered to explain its outburst, as well as those of other
temporary stars, one of the most fruitful is that of a collision
between a star and a vast invisible nebula. Professor Seeliger, of
Munich, first proposed this theory, but it afterward underwent some
modifications from others. Stated in a general form, the idea is that
a huge dark body, perhaps an extinguished sun, encountered in its