en circulate to the bottom of the
liquor; at others, it will only reach a little down its neck. The
great caution to be used in making this experiment, is the making the
vapour of a proper heat; for if made too cold few vapours will arise;
and, if made too hot, they will arise too fast, and will only take
fire in the neck of the glass, without any remarkable coruscation.

_To produce Fire from Cane._

The Chinese rattans, which are used, when split, for making cane
chairs, will, when dry, if struck against each other, give fire; and
are used accordingly in some places, in lieu of flint and steel.

_To make an Eolian Harp._

This instrument may be made by almost any carpenter: it consists of a
long narrow box of very thin deal, about five or six inches deep, with
a circle in the middle of the upper side, of an inch and a half in
diameter, in which are to be drilled small holes. On this side, seven,
ten, or more strings, of very fine gut, are stretched over bridges at
each end, like the bridges of a fiddle, and screwed up or relaxed with
screw pins. The strings must be all tuned to one and the same note,
and the instrument be placed in some current of air, where the wind
can pass over its strings with freedom. A window, of which the width
is exactly equal to the length of the harp, with the sash just raised
to give the air admission, is a proper situation. When the air blows
upon these strings, with different degrees of force, it will excite
different tones of sounds; sometimes the blast brings out all the
tones in full concert, and sometimes it sinks them to the softest
murmurs.

_To show the Pressure of the Atmosphere._

Invert a tall glass or jar in a dish of water, and place a lighted
taper under it: as the taper consumes the air in the jar its pressure
becomes less on the water immediately under the jar; while the
pressure of the atmosphere on the water _without_ the circle of the
jar remaining the same, part of the water in the dish will be forced
up into the jar, to supply the place of the air which the taper has
consumed. Nothing but the pressure of the atmosphere could thus cause
part of the water to rise within the jar, above its own level.

_Subaqueous Exhalation._

Pour a little clear water into a small glass tumbler, and put one or
two small pieces of phosphoret of lime into it. In a short time,
flashes of fire will dart from the surface of the water, and terminate
in ringlets of smoke, whic