The daily exchange. [volume] (Baltimore, Md.) 1858-1861, 1858-07-21
SCIENCE AND ART.

APPARATUS FOR RAILWAY SIGNALLING.-An appa-
tus of some merit has been devised for working in
cOnjunction with railway signals and designed to
act dctector, by proving in the event of an ac-
cidcnt occurring, whether the warning signal was
was not set at the time of the passing of the
train. The plan consists in placing supplementary
signal or semaphore between the station signal and
the distance signal, beyond the latter beyond
both. The supplementary signal is worked in CON
nection with, and by the same handle either the
station the distance signal and is used for indi-
eating whether the or the other Of these signals
was set at the time the engine passed it. 1t stands
only high the buffer beam of the engine and is
placed near the rails, that whenan arm is thrown
out thcrctrom to danger, the engine cannot pass
without breaking it down. The arm is placed in
socket, and may be readily replaced when broken;
or the arm may be pointed in such a manner that,
instead of being broken portion of may be turned
out of its transverse position, and thus indicate the
passage OF the engine
ANOTHER MoDE OF NAVIGATING THE Am.-Nuch
has been said, of late, respecting aerial machine
invented by the Nisc0unt Curlingford, and great
results appear to be anticipated by the inventor and
others from its This machine, chariot it
is called is in form something like boat extremely
light, with one wheel in front and two behind turn
ing two wings slightly concave fixed to its sides,
and sustained by laths ofa halfhollow form pressing
against them, and communicating their pressure
through the body OF the machine from one wing to
the other, and supported by cords whose force act
ing on two hoops nearly Of oval shape, hold the
wings firmly in their position, using force of not
less than ten TONS on the well known principle OF
corded musical instruments.
Another popularity Of this machine is that it is
provided with tail that can be raised or lowered at
pleasure, and which serves for giving eIevatng
Or declining position and worked by cord that
communicates into the interior of the machine, be
ing drawn forward by what is termed a aerial
screw, which screws into the air at an elevation of
torty-iive degrees, similar to birds wing, and
turned by means of Il winch acting on three multi
plying wheels. The wings of the machine
cred with network, of heightened square shape,
which produces the effect of birds feathers when
the chariot toOts on the air, covered with silk, but
so adjusted that pocket, it were, be form
ed by the pressure of the silk on the air. The upper
part is finished pl the manner, and both sides
Of the wings are covered with varnish.
AsrRoNoMICAL PECUIARTrEs OF THE MooN's
SURFACE AND ATNoSPHEGE-It is gen
orally received theory in astronomy that
the moons axis is nearly perpendicular to the
plane of the ccliptic, she scarcely have
any change of seasons But, what is still more
markable, one-half of the moon has no darkness at
ALL while the other half has two weeks Of light
and two of darkness alternately; the inhabitants, if
any, of the first half bask constantly in carthshine,
without seeing the sun, whilst those of the latter
the earth at all; for the earth reflects the
light of the sun to the moon, in the same manner
as the moon does to the earth; therefore, at the
time OF conjunction, moon, her further side
must be enlightened by the sun, and the nearer half
by the earth, and at the time of opposition,
full moon, one half of her will be enlightened
by the sun, but the other half in total darkness
To the luminares the earth must seem the largest
orb in the universe; for it appears to them more
than three times the size Of the sun, and thirteen
times greater than the moon does to us-exhibiting
similar phases to herself, but in reverse order;
for when the moon is full the earth is invisible to
them, and when the moon is they win see the
earth full The face Of the moon appears to us per
manent but to them the earth presents very differ
ent appearances; thus, the Pacific and Atlantic
oceans, in the course of each twenty-four hours,
will successvely rivet their attention, and the
locity Of motion must excite both surprise and
lecture. The best modern telescopes make the
moon appear to us as she would to the naked eye
were she only $50 miles off.