eoscope, would appear as a solid sphere, in which condition we
should doubtless get such an acquaintance with the surface of our
satellite as can be obtained by no other means. The reason for taking
the images with so long an interval between is, that although each one
represents the same object, each must be taken at a different angle;
and for an object so distant as the moon, the difference caused by the
libration would, it is believed, be sufficient for the desired result.
In the small pictures, however, the difference of angle is so slight,
that to the unpractised observer they appear precisely alike; it is,
nevertheless, essential to the effect that the variation, though
minute, should exist. With respect to the pseudoscope--which makes the
outside of a teacup appear as the inside, and the inside as the
outside; which transforms convexity into concavity, and the reverse;
and a sculptured face into a hollow mask; which makes the tree in your
garden appear inside your room, and the branches farthest off come
nearest to the eye; and which, when you look at your pictures,
represents them as sunk into a deep recess in the wall,--with respect
to this instrument, its practical uses have yet to be discovered. But
as your celebrated countryman, Sir David Brewster, is working at the
subject, as well as Mr Wheatstone, we shall not, so say the initiated,
have to wait long for further results.

Besides these lectures, a course is being delivered at the Museum of
Practical Geology, recently opened in Jermyn Street, by eminent
professors, as you may judge from the fact of De la Beche, Forbes, and
Playfair being among them. Some of the most promising of the pupils at
the School of Design are allowed to attend these lectures gratis. At
the same institution, an attempt is to be made to do what has long
been done in Paris--namely, to admit working-people to the best
scientific lectures free of cost. Now, therefore, is the time for the
working-men of the metropolis to shew whether they wish for knowledge
and enlightenment or not. They have only to present themselves at the
Museum, pay a registration-fee of sixpence, conform to the rules, and
so qualify themselves for the course of six lectures. It is a capital
opportunity; and I, for one, hope that hundreds of the intelligent
working-men of London will avail themselves of it. They, on their
part, may find government education not unacceptable; and government,
on the other hand, encour