at observatories.
That telescope would be still but a comparatively small one which
would show as many stars in the sky as there are people living in the
mighty city of London; and with the greatest instruments, the tale of
stars has risen to a number far greater than that of the entire
population of Great Britain.

In addition to those stars which the largest telescopes show us, there
are myriads which make their presence evident in a wholly different
way. It is only in quite recent times that an attempt has been made to
develop fully the powers of photography in representing the celestial
objects. On a photographic plate which has been exposed to the sky in
a great telescope the stars are recorded by thousands. Many of these
may, of course, be observed with a good telescope, but there are not a
few others which no one ever saw in a telescope, which apparently no
one ever could see, though the photograph is able to show them. We do
not, however, employ a camera like that which the photographer uses
who is going to take your portrait. The astronomer's plate is put into
his telescope, and then the telescope is turned towards the sky. On
that plate the stars produce their images, each by its own light. Some
of these images are excessively faint, but we give a very long
exposure of an hour or two hours; sometimes as much as four hours'
exposure is given to a plate so sensitive that a mere fraction of a
second would sufficiently expose it during the ordinary practice of
taking a photograph in daylight. We thus afford sufficient time to
enable the fainter objects to indicate their presence upon the
sensitive film. Even with an exposure of a single hour a picture
exhibiting sixteen thousand stars has been taken by Mr. Isaac Roberts,
of Liverpool. Yet the portion of the sky which it represents is only
one ten-thousandth part of the entire heavens. It should be added that
the region which Mr. Roberts has photographed is furnished with stars
in rather exceptional profusion.

Here, at last, we have obtained some conception of the sublime scale
on which the stellar universe is constructed. Yet even these plates
cannot represent all the stars that the heavens contain. We have every
reason for knowing that with larger telescopes, with more sensitive
plates, with more prolonged exposures, ever fresh myriads of stars
will be brought within our view.

You must remember that every one of these stars is truly a sun, a
lamp, as it wer