eye of the pair may look precisely through
the centre of the half lens presented to it.
Under such prisms the stereoscopic pictures
are adjusted.

Minute details upon subjects of this kind
must of course be sought in other publications.
We must in this place be satisfied if
we convey general ideas of a just kind upon
such topics: a notion of the stereoscope—and
at the best no more has now been given—as
we attempted on a former occasion to convey
a notion of photography. We desire to note
in this place that in our brief sketch of the
processes of that art, we conveyed among
other things an error by a slip of the scribe,
which set down dilute pyrogallic acid as an
agent used for fixing the picture on the
metallic plate. A solution of hyposulphate
of soda was the agent that should have been
named. Having stepped aside to correct that
erratum, we return to our proper subject and
have to content ourselves now with a final
word or two about the pseudoscope; an
instrument of which the name implies "falsehoods,
I see."

If we cheat the eyes in a stereoscope by
showing to each eye the picture that belongs
only to its neighbour's point of view, everything
is perverted. Upon every point, not
immediately in the middle line between and
before the two eyes, the optic axes must
converge in the wrong way, and objects or
parts of objects will appear distant in
proportion as they otherwise would have seemed
near.

The pseudoscope is especially contrived for
the illustration of this fact. It is a little
instrument, convenient as an opera glass in
the hand and as easily adjusted. It consists
of two prisms of flint glass, so joined, that
they may be adjusted before the eyes to the
exact focus of observation of any object. The
prisms reflect the two images of any one
thing—each apparently but not actually to
the wrong eye—and, when the instrument
is so adjusted that the two images coincide
and the object consequently appears single,
the observer is at once subjected to illusions
of the oddest kind. A globe, so observed,
may for a minute be a globe, but after the
spectator has gazed at its rotundity for a
short while, suddenly, as if without cause, it
appears to be converted into a concave
hemisphere, over the brim of which continents are
flowing as the globe revolves. A China cup,
with coloured ornaments upon it in relief,
becomes a mould of half the cup with painted
hollow impressions of the flowers inside,
instead of outside.

The suddenness of the metamorphosis
suffered by such a cup belongs, one might say,
wholly to the days of sorcery. The explanation
is, however, very natural. Relief and distance
are not suggested solely by the use of two
eyes and the convergence of their optic axes.
We are accustomed to note other signs which
are perceived by each eye singly. The idea
of relief being suggested by the presence
of some signs, the eyes at first are apt
to dwell upon them, and are not
disposed to be immediately disturbed in their
impression.

FIRST STAGE TO AUSTRALIA.

It is of no use pretending not to know
where Park Street, Westminster, is. Don't
ask your way of the crossing-sweeper. Don't
enquire of the policeman at the corner.
You need not trouble the elderly woman
of the fruit stall to point out to you the
direction of this Open Sesame of the Great
South Land—the abode of these official
guardians of the Golden Regions, according to
popular belief. Follow the stream of fustian
jackets, corduroy trousers and smock-frocks,
keep in the rear of the chattering, excited
parties of half-shaven mechanics, slatternly
females, and slip-shod children. They are
all moving in one direction, and you could
not miss your way if you tried, for it's
much easier to follow this stream than to
move against it.

Across the broad street, along the pavement
on the right-hand side, cross over again,
keep straight on, round a little to the left,
then sharp to the right, and the third house
on the right-hand side, if we can but get
at it through the crowd, is the much-sought
office of the Commissioners of Land and
Emigration. The dense throng of impromptu
sheep-shearers, ready-made agriculturists,
and shepherds by inspiration, find it difficult
to get through the iron wicket and down the
steep stone steps into the area, where they
are compelled to pass to the lower waiting-
room. Indeed, it is almost as intricate and
dangerous an undertaking as wading through
the labyrinth of type comprised in the thirty-
four rules of the Commissioners. There is a
warm and lively performance going on in
that waiting-room down below the iron
wicket amongst the ready-made farm
servants from Whitechapel and the shepherds
of Shoreditch. It would be impossible to
say precisely how many tongues were going
at once about steerage passages, and sea-
sickness, and split peas.

Up the cold, broad, stone staircase, and in
the first floor on the left hand, is a quiet, busy
room, full of active clerks—a Custom House
Long Room In miniature. Pens are traveling
over acres of paper ruled in an infinity
of tabular forms: heads are reckoning up
shiploads of shepherds with three children
and wheelwrights with one, and carpenters
with only a wife. Senior clerks are adding
up and tabulating the totals of male and
female statute adults shipped by the
"Wiggins" for Adelaide and the "Scroggins" for
Port Phillip, and a table-full of supernumerary
deputy-assistant clerks are ticking off
as many single young women as they can
afford to do for six shillings a-day. There