The works of Francis Bacon, lord chancellor of England.

CENT. VIII. NATURAL HISTORY. 103
so as you do not see the water. Then put a look- that the palm of the hand, though it hath as thin
ing-glass in the water: now if you can see the a skiin as the other parts mentioned, yet is not
devil's picture aside, not seeing the water, it ticklish, because it is accustomed to be touched.
would look like a devil indeed. They have an Tickling also causeth laughter. The cause may
old tale in Oxford, that Friar Bacon walked he- be the emission of the spirits, and so of the breath,
tween two steeples: which was thought to be by a flight from titillation; for upon tickling we
done by glasses, when he walked upon the see there is ever a starting or shrinking away
ground. of the part to avoid it; and we see also, that if
you tickle the nostrils with a feather, or straw,
Experiments in consort touching impulsion and it procureth sneezing; which is a sudden emispercussion. sion of the spirits, that do likewise expel the
763. A weighty body put into motion is more moisture. And tickling is ever painful, and not
easily impelled than at first when it resteth. The well endured.
cause is partly because motion doth discuss the
cause is partly because motion doth discuss the Experiment solitary touching the scarcity of rain
torpor of solid bodies; which, besides their mo- i E v
in Egypt.
tion of gravity, have in them a natural appetite
not to move at all; and partly, because a body 767. It is strange, that the river of Nilus overthat resteth, doth get, by the resistance of the flowing, as it doth, the country of Egypt, there
body upon which it resteth, a stronger compres-s be, nevertheless, little or no rain in that
sion of parts than it hath of itself: and therefore country. The cause must be either in the nature
needeth more force to be put in motion. For if of the water, or in the nature of the air, or of both.
a weighty body be pensile, and hang but by a In the water, it may be ascribed either unto the
thread, the percussion will make an impulsion long race of the water; for swift-running waters
very near as easily as if it were already in motion. vapour not so much as standing waters; or else to
764. A body over-great or over-small will not the concoction of the water; for waters well conbe thrown so far as a body of a middle size: so cocted vapour not so much as waters raw; no
that it seemeth there must be a commensuration, more than waters upon the fire do vapour so much
or proportion between the body moved and the after some time of boiling as at the first. And it
force, to make it move well. The cause is, be- is true thatt he water of Nilus is sweeter than
cause to the impulsion there is requisite the force other waters in taste; and it is excellent good for
of the body that moveth, and the resistance of the stone, and hypochondriacal melancholy, which
the body that is moved: and if the body be too showeth it is lenifying; and it runneth through a
great, it yieldeth too little; and if it be too small, country of a hot climate, and flat, without shade,
it resisteth too little, either of woods or hills, whereby the sun must
765. It is common experience, that no weight needs have great power to concoct it. As for the
will press or cut so strong, being laid upon a air, from whence I conceive this want of showers
body, as falling or stricken from above. It may cometh chiefly, the cause must be, for that the air
be the air hath some part in furthering the per- is of itself thin and thirsty; and as soon as ever
cussion; but the chief cause I take to be, for that it getteth any moisture from the water, it imbibeth
the parts of the body moved have by impulsion, and dissipateth it in the whole body of the air,
or by the motion of gravity continued, a com- and suffereth it not to remain in vapour, whereby
pression in them, as well downwards, as they it might breed rain.
have when they are thrown, or shot through the Excperiment solitary touching clarification.
air, forwards. I conceive also, that the quicik 768. It hath been touched in the title of percoloose of that motion preventeth the resistance of lations, namely, such as are inwards, that the
the body below: and the priority of the force al- whites of eggs and milk do clarify; and it is cerways is of great efficacy, as appeareth in infinite tai, that in Egypt they prepare and clarify the
water of Nile, by putting it into great jars of
stone, and stirring it about with a few staniped alExperiment solitary touching titillation.,
monds, wherewith they also besmear the mouth
766. Tickling is most in the soles of the feet, of the vessel; and so draw it off, after it hath
and under the arm-holes, and on the sides. The rested some time. It were good to try this claricause is the thinness of the skin in those parts, fying with almonds in new beer, or muste, to
joined with the rareness of being touched there: hasten and perfect the clarifying.
for all tickling is a light motion of the spirits,
which the thinness of the skin, and suddenness Experiment solitary touching plants without leaves,
and rareness of touch do further: for we see a 769. There be scarce to be found any vegetafeather, or a rush, drawn along the lip or cheek, bles, that have branches and no leaves, except
doth tickle; whereas a thing more obtuse, or a you allow coral for one. But there is also in the
touch more hard, doth not. And for suddenness, deserts of S. Macario in Egypt, a plant which is
we see no man can tickle himself: we see also long, leafless, brown of colour, and branched like