The works of Francis Bacon, lord chancellor of England.

566 PHENOMENA OF THE UNIVERSE.
so a sound is produced between a solid body and hollow vessel might be constructed of metal, or
air condensed, and again between two opposite of some other kind of material, to be let down to
bodies of condensed air. For, with respect to the the bottom of the water; that it might be suschords in musical instruments, it is plain that the tained by a tripod, with the feet affixed to the
sound is not emitted by touch, or by the percus- brim of the vessel, and the feet to be a little less
sion between the finger or the bow, but between than the human stature. The vessel was let
the chord and the air. down into a great depth, with all the air it conFor a chord when it rebounds, and that with tained, in the same manner as was described in
celerity from its being stretched, first condenses the case of the platter, and was set upon its feet,
the air, and then strikes it. Instruments also put and stood just by the spot where the work was to
into sound by the breath, on account of the very be carried on. But the divers, who were the
weak motion of the breath compared with that of workmen, when they wanted respiration put their
a stringed instrument, are of necessity made heads into the hollow of the vessel, and having
hollow to assist the compression of the air, which taken a supply of air, returned to their work. And
is also considered an assistance in stringed in- I myself in a bath made my servant put his head
struments. into a basin under the water depressed with air,
Water pent up makes a way for itself with a and he so remained for half the quarter of an hour,
powerful impetus, and diffuses itself on all sides, until he felt that the air, warmed by his breath,
in order to obtain its natural latitude, as under the brought on a feeling of suffocation.
arches of bridges. In the same manner also wind To try by the bladder whether air readily
narrowed and condensed bursts forth with vio- admits of some small contraction, would be a fallence. Whirlpools produce whirlpools, for, since lacious experiment. For when the bladder is
the natural relaxation is impeded, each part sus- filled with wind, the air is condensed by the wind
tains an equal pressure. itself, so that the air within the bladder is more
Water emitted on a sudden with force from a dense than common air, and therefore may be exconfined space, reflects the resemblance of a con- pected to be less adapted to a new condensation.
tinuous body, as of a thread or rod, or branch of a But in the usual experiment of the wooden plate
tree, and becomes straight, afterward bends, then forced down beneath the water, you may see that
divides itself, and disperses itself into a circle the water, entering from the extreme part of the
into drops, as in little pipes, or syringes, and vessel, has occupied some space, and that the air
gutters. has occasioned a defalcation of the same space.
There is a kind of pool not uncommon in ponds, But in order more clearly to illustrate the proespecially after hay has been mown, or rather portion, I placed a small globular, or other solid
seen from that circumstance. The hurricane body, and that would sink, at the bottom of the
sometimes raises a quantity of hay in the air, and vessel, above which the plate was to be placed;
carries it along for a time together and not scat- then I placed above that another plate, metallic
tered, until, after it has been borne to a considerable and not wooden, that could stand of itself at the
height, the hay disperses itself and forms, as it bottom of the vessel. But if that body be small
were, a canopy. in size, when it is received into the hollow of the
A wooden platter, empty and turned down- plate, it forces the air together, and does not
wards, and placed evenly on the surface of the expel it; but if of greater magnitude than to
water, and afterward put under the water, bears admit of the easy yielding of the air, the air, imwith it down to the bottom of the vessel the air patient of this greater pressure, somewhat lifts up
before contained in the platter; but if, with the the plate, and ascends in bubbles.
like equilibrium, it be again taken out of the And I had a hollow leaden globe made, the sides
water, you will find the air to have conveyed of it sufficiently firm to bear the force of a mallet or
itself into not much less space than it before of a press: and this globe, being struck at either
filled. This will appear from the colouring of pole with mallets, approached nearer and nearer
the lip of the platter at the place whither the to a planisphere. And it yielded more readily
water had ascended, and from which the air under the first contusions, afterward less so, acreceived itself within. cording to the measure of the condensation; so
In a bed-room, if a window be left open when that at the last the mallets were of but little serthe wind blows, if there be no other vent, it is not vice, and there was need of pressing, and that
very much felt, (unless it be violent,) since it is with some violence. But I enjoined, that, after
not received by the body of wind which had filled the pressing, a few days should be suffered to
the room, and was somewhat condensed by the elapse, but this has no relation to our present
first gentle wind, and afterwards does not admit design, but looks another way.
of condensation; but as soon as a vent is given, Air, by a powerful exsuction into closed vesit is then manifestly perceived. sels, is extended or dilated, so that part of the air
For the more comfortable continuance of work- being removed, the remainder, nevertheless, fills
Jnen under water, it has been thought that a large the same measure as the whole had filled; and yet