even of a well-marked thinning out, of stars.

If, as was formerly supposed, the stars did not greatly differ in
the amount of light emitted by each, and if their diversity of
apparent magnitude were due principally to the greater distance of
the fainter stars, then the brightness of a star would enable us
to form a more or less approximate idea of its distance. But the
accumulated researches of the past seventy years show that the
stars differ so enormously in their actual luminosity that the
apparent brightness of a star affords us only a very imperfect
indication of its distance. While, in the general average, the
brighter stars must be nearer to us than the fainter ones, it by
no means follows that a very bright star, even of the first
magnitude, is among the nearer to our system. Two stars are worthy
of especial mention in this connection, Canopus and Rigel. The
first is, with the single exception of Sirius, the brightest star
in the heavens. The other is a star of the first magnitude in the
southwest corner of Orion. The most long-continued and complete
measures of parallax yet made are those carried on by Gill, at the
Cape of Good Hope, on these two and some other bright stars. The
results, published in 1901, show that neither of these bodies has
any parallax that can be measured by the most refined instrumental
means known to astronomy. In other words, the distance of these
stars is immeasurably great. The actual amount of light emitted by
each is certainly thousands and probably tens of thousands of
times that of the sun.

Notwithstanding the difficulties that surround the subject, we can
at least say something of the distance of a considerable number of
the stars. Two methods are available for our estimate--measures of