our sun and gives out twenty times as much light. Canopus emits
20,000 times as much light as the sun, but we cannot say, in this
case, how much larger it is than the sun. Arcturus, however,
belongs to the same class of stars as our sun, and astronomers
conclude that it must be thousands of times larger than the sun.
A few stars are known to be smaller than the sun. Some are,
intrinsically, far more brilliant; some far less brilliant.

Another method has been adopted, though this also must be
regarded with great reserve. The distance of the nearer stars can
be positively measured, and this has been done in a large number
of cases. The proportion of such cases to the whole is still very
small, but, as far as the results go, we find that stars of the
first magnitude are, on the average, nearly 200 billion miles
away; stars of the second magnitude nearly 300 billion; and stars
of the third magnitude 450 billion. If this fifty per cent
increase of distance for each lower magnitude of stars were
certain and constant, the stars of the eighth magnitude would be
3000 billion miles away, and stars of the sixteenth magnitude
would be 100,000 billion miles away; and there are still two
fainter classes of stars which are registered on long-exposure
photographs. The mere vastness of these figures is immaterial to
the astronomer, but he warns us that the method is uncertain. We
may be content to conclude that the starry universe over which
our great telescopes keep watch stretches for thousands, and
probably tens of thousands, of billions of miles. There are
myriads of stars so remote that, though each is a vast
incandescent globe at a temperature of many thousand degrees, and
though their light is concentrated on the mirrors or in the
lenses of our largest telescopes and directed upon the