[Illustration: Diagram of apparatus as described in text]
There is also another contrivance by which liquid is borne steadily
upwards and remains, so as to seem perpetually ascending. Let A B (fig.
53), be a perfectly air-tight pedestal, furnished with a partition, C
D, and a cylindrical glass cover, E F, also perfectly air-tight. In the
cover E F let there be a tube, G H, reaching nearly to the top, and
passing through an orifice in the partition C D, and another tube, K
L, passing through the top of the pedestal but not descending quite so
low as the partition. In the pedestal, and outside the glass cover, let
there be an aperture, M, through which the vessel A D is to be filled,
and near the bottom of the pedestal a spout, N; also one other tube, X
O, passing through the partition and reaching nearly to the bottom of
the pedestal, through which the vessel C B may be filled. If the spout,
N, be closed the air in C B will pass out through the tubes G H, K L,
and the hole M; and when C B is full we must fill A D through the hole
M, for the air contained in it will pass out through the same hole.
Now, if we set the spout N free, the air in the glass cover will pass
through the tube G H into the void space left in C B, and water will
ascend from A D through the tube K L into the void space left in the
cover, while into the void of the vessel A D air will enter through
the aperture M; and this will go on until the glass cover is filled:
but the spaces A D, C B, E F, must be of equal capacity that the air
and water may take the place of one another. When C B is exhausted and
the continuity of the air is broken, the water will again descend out
of the glass cover into A D, air passing into the cover through the
spout N and the tube G H. The air in A D will pass out through the
aperture M.
54. _Water driven from the Mouth of a Wine-skin in the Hands of a
Satyr, by means of compressed Air._
[Illustration: Diagram of apparatus as described in text]
If wind is blown through the mouth of certain figures, they spout
up water through some other place. For example, if a satyr holds a
wine-skin, water shall be spouted up through the skin. A B C D (fig.
54), is an air-tight pedestal on which the figure is placed; through
the mouth of the figure a tube, E F, is inserted, communicating with
the pedestal, and having underneath it a small plate, G H, which
closes the aperture F of the tube, and is supported by pins to which
buttons are attached, that the plate may not fall off. Another tube,
K L, is passed through the pedestal, of which the extremity, K, must
be contiguous to the point at which the water-jet is to be, and the
extremity, L, reach to the bottom of the pedestal, leaving only a
passage for the water. At the extremity K there must be a valve or tap
by which the aperture K, which is very small, may be shut. Now if we
pour any quantity of water into the pedestal through a hole, which we
must afterwards stop, and, having closed the aperture K, blow in air
through the tube E F, the air blown in will thrust aside the plate and
descend into the pedestal: and, if this is done several times, the
air in the pedestal will be compressed and close the plate. Let the
valve or tap be opened, and after a short time the compressed air will
drive the liquid in the pedestal violently out through the aperture K,
until all the liquid is spouted up, and the air is brought back to its
natural state, that is, in which it is no longer subject to compression.
55. _A Vessel, out of which Water flows as it is poured in, but if the
supply is withheld, Water will not flow again, until the Vessel is half
filled; and on the supply being again stopped, it will not then flow
until the Vessel is filled._
[Illustration: Diagram of apparatus as described in text]
There are some vessels which, when water is poured in, flow
immediately, but, if we discontinue pouring for a short space, do
not flow again, though water is poured in afresh, till they are half
full, when they begin to flow once more; and if we discontinue again,
do not flow any more till they are quite full. Let A B (fig. 55),
be a vessel containing, concealed in its interior, three siphons, C,
D, E, one leg of each being near the bottom of the vessel,
while the other, fashioned into a water-spout, conducts outside the
vessel. At the outer extremities of the siphons, apply vessels, F,
G, H, the bottoms of which are far enough from the orifices of
the siphons to admit the passage of water between; and let all this be
encompassed by another vessel, as it were a pedestal, K L M N, which is
provided with a spout at X. Let the bend of the siphon C be close to
the bottom of the vessel A B; that of D, half way up its height, and
that of E, near the neck. Now, if we pour water into the vessel A B, it
will immediately flow through the siphon C since its bend is near the
bottom: but, if we cease pouring, the liquid poured in will be drawn
off through the pipe F, and the vessel F will be found full of water,
while the other part of the siphon C will be full of air. Consequently,
when liquid is again poured into the vessel, it will not pass through
the siphon C, owing to the air which is contained in the siphon between
the water which is being poured in and that in the vessel F. The liquid
will therefore rise as high as the bend of the siphon D, which is at
the middle of the vessel, and then it will begin to flow: but, if we
again cease pouring, the same will happen as has been explained in the
case of the siphon C. A like result must be imagined with the siphon
E. It will be necessary to pour in the stream gently, that the air
intercepted in the siphon may not be forcibly driven out.
56. _A Cupping-Glass, to which is attached an Air-exhausted
Compartment._
[Illustration: Diagram of apparatus as described in text]
The construction of a cupping-glass which shall attract without the aid
of fire. Let A B C (fig. 56), be a cupping-glass, such as is usually
applied to the body, having a partition across it, D E: through the
bottom of the cupping-glass let two sliding tubes be inserted, F G
being the outer tube and H K the inner; and in these, but outside the
cupping-glass, pierce corresponding holes, L and M. Let the inner
extremities of both the tubes be open, but the outer extremity of
H K be closed and provided with a handle. Under the partition D E
place another pair of sliding tubes, N X, like those just described;
but the corresponding holes must be within the cupping-glass, and be
precisely adapted to a hole in the partition. When these perforations
are complete, let the handles of the sliding tubes be turned round, so
that the holes in the lower tubes may be in a line, while those under
the partition, not being allowed to coincide, remain closed. Now, the
chamber D C being full of air, by applying the orifice L M to the mouth
we can suck out a portion of that air; and then, by turning the handle
again and not removing the tubes from the mouth, we can keep the air
in the vessel C D rarefied; and this must be repeated until we have
drawn off a large quantity of air. Then, applying the glass to the
flesh in the usual manner, we open the holes in the sliding tubes N X
by means of the handle; and it must follow that some of the air in the
vessel A D E will pass into the place of the air withdrawn from C D,
while into the void thus created both the flesh and the matter about
it will be drawn up through the interstices of the flesh which we call
invisible spaces or pores.