three magnitudes smaller
than the smallest star visible to the naked eye on a dark night. There
was a time when Polaris, as a double, was regarded as an excellent
test for a good three inch telescope; that is any three inch
instrument in which the companion could be seen was pronounced to be
first-class. But so persistently have instruments of small aperture
been improved that that star is no longer an absolute test for three
inch objectives of fine quality, or any first-rate objective exceeding
two inches for which Dawes proposed it as a standard of excellence, he
having found that if the eye and telescope be good, the companion to
Polaris may be seen with such an aperture armed with a power of
eighty. As a matter of fact, Dawes, who was, like Burnham, blessed
with most acute vision, saw the companion with an instrument no larger
than this small one in my hand--one inch and three-tenths. Ward saw it
with an inch and one-quarter objective, and Dawson with so small an
aperture as one inch. T.T. Smith has seen it with a reflector stopped
down to one inch and one-quarter, while in the instrument still known
as the "great Dorpat reflector," it has been seen in broad daylight.
This historic telescope has, I believe, a twelve inch object glass,
but the difficulty of seeing in sunshine so minute a star is such that
the fact may fairly be mentioned here.

Another interesting feature is this. Objects once discovered, though
thought to be visible in large telescopes only, may often be seen in
much smaller ones. The first Herschel said truly that less optical
power will show an object than was required for its discovery. The
rifts, or canals, in the Great Nebula in Andromeda is a case in point,
but two better illustrations may be taken from the planets. Though
Saturn was for many years subjected to most careful scrutiny by
skilled astronomers using the most powerful telescopes in existence,
the crape ring eluded discovery until November, 1850, when it was
independently seen by Dawes, in England, and Bond, in the United
States. Both were capital observers and employed excellent instruments
of large aperture, and it was naturally presumed that only such
instruments could show the novel Saturnian feature. Not so. Once
brought to the attention of astronomers, Webb saw the new ring with
his three and seven-tenths telescope and Ross with an aperture not
exceeding three and three-eighths in diameter. Nay, I am permitted to
say that a ve