icated that their
composition was not stellar but gaseous. Their spectra consist of a few
bright lines revealing the presence of hydrogen, nitrogen, and other
gaseous elements.

Much that is mysterious and uncertain is associated with those objects
which appear to lie far beyond the limits of our sidereal system. It is
now generally believed that they exhibit the earliest stage in the
formation of stars and planets--inchoate worlds in process of slow
evolution, which will eventually condense into systems of suns, and
planetary worlds.

Nebulae present every variety of form. Some are annular, elliptic,
circular, and spiral; others are fan-shaped, cylindrical, and irregular,
with tufted appendages, rays, and filaments. A fancied resemblance to
different animated creatures has been observed in some. In Taurus there
is a nebula called the 'Crab' on account of its likeness to the
crustacean; another is called the 'Owl Nebula' from its resemblance to
the face of that bird. The Orion Nebula suggests the opened jaws of a
fish or sea monster, hence called the Fish-Mouth Nebula. There is a
Horse-Shoe Nebula, a Dumb-Bell Nebula, and many others of various shapes
and forms. They are classified as follows: (1) Annular Nebulae, (2)
Elliptic Nebulae, (3) Spiral Nebulae, (4) Planetary Nebulae, (5) Nebulous
Stars, (6) Large Irregular Nebulae.

ANNULAR NEBULAE.--These resemble in appearance an oval-shaped luminous
ring; they are comparatively few in number, and not more than a dozen
have been discovered in the whole heavens. The most remarkable object of
this class is the Ring Nebula, which is situated between the stars Beta
and Gamma Lyrae. It is visible in a moderate-sized telescope as a
well-defined, flat, oval ring; its central part is not quite dark but is
occupied by a filmy haze of luminous matter which is prolonged inwards
from the margin of the ring. When examined with a high power the edges
of the ring have a fringed appearance, and numerous glittering stellar
points become visible both within and without its circumference. This
nebulous ring, though a small object in the telescope, is of enormous
magnitude, and if it were not more distant than 61 Cygni, one of the
nearest of the fixed stars, its diameter would not be less than 20,000
millions of miles, but it has been estimated by Herschel that it is 900
times more remote than Sirius. How stupendous, then, must be its
dimensions, and how bewildering to our conception is the