[Illustration: Diagram of apparatus as described in text]
When a fire is kindled on an altar, figures shall be seen to dance: for
the altars must be transparent, either of glass or horn. Through the
hearth of the altar (fig. 70), a tube is let down turning on a pivot
towards the base of the altar, and, above, on a small pipe which is
attached to the hearth. Communicating with, and attached to, this tube
are smaller tubes lying at right angles to each other, and bent at the
extremities in opposite directions. A wheel or platform on which the
dancing figures stand, is also fastened to the tube. When the sacrifice
is kindled, the air, growing hot, will pass through the pipe into the
tube, and be forced out of this into the smaller tubes; when, meeting
with resistance from the sides of the altar, it will cause the tube and
the dancing figures to revolve.
71. _A Lamp in which the Oil can be raised by Water contained within
its Stand._
[Illustration: Diagram of apparatus as described in text]
The construction of a lamp-stand, such that, if a lamp is placed upon
it, whenever the oil fails, a supply shall be poured into it from the
handle to the amount required, though no vessel is placed upon the lamp
from which the oil can flow into it. Let the lamp-stand be constructed
with a triangular pedestal, like a pyramid, A B C D (fig. 71), hollow
and provided with a partition E F. Let G H, which must also be hollow,
be the shaft of the lamp-stand, and above this shaft place a hollow
cup, K L, capable of containing a considerable quantity of oil. From
the partition E F, and fitting closely into it, a tube, M N, must
extend upwards, leaving a passage for the air between its extremity
and the covering of the cup, K L, on which the lamp is placed. Through
the plate K L insert another small tube X Q, a passage being left for
water between it and the bottom of the cup: the tube X Q must project a
little above the plate K L, and into the projecting part another pipe P
is tightly fitted, closed at its upper extremity, and passing through
the bottom of the lamp so as to be included within it, that there may
be no projection outside. To P solder another pipe, extremely fine,
communicating with it, and reaching to the extremity of the handle, so
that its stream will be carried into the body of the lamp; this pipe
must have an orifice like the others. Under the partition E F let a
tap be soldered leading into the chamber C D E F, so that, when it is
opened, the water in the chamber A B E F will pass into C D E F. In the
plate A B let a fine hole be perforated through which A B E F may be
filled with water; the [air] contained in it will pass out through the
same hole. We now remove the lamp and fill the cup with oil through the
pipe X Q, the air escaping through M N, and again through an open cock
in the bottom C D, when any water in C D E F has first flowed out. The
lamp having been placed on the top by means of the sliding tube P, when
it is required to pour in oil, we must open the tap in the plate E F,
and the water in the chamber A B E F passing into C D E F, the air in
C D E F will reach the cup through the tube M N, and force out the oil
contained in it: the oil will pass into the lamp through the tube X Q
and the pipe attached to it. When we wish the oil to stop running, we
must shut the cock and the discharge will cease. This process can be
repeated whenever it is necessary.