'Take away that yellow surface which covers the orange and distil it in a retort until the extract is pronounced perfect.'
AN EXPERIMENT WITH THE SENSE OF TOUCH
If you place your second finger under the tip of the third in such a
way that the whole of the nail is visible on the far side, then anything
that is touched by these two fingers will seem double, provided that
the object touched is round. c.a. 204 v. a
I take a vessel filled with wine and I draw of? the half and fill it up
again with water: in consequence the vessel will contain half wine
and half water.
Then I draw ofl half again and then fill up with water, wherefore
there remains . . .
Since every continuous quantity is divisible to infinity, if a quantity
of wine be placed in a vessel through which water is continually passing
it will never come about that the water which is in the vessel will be
without wine. . c.a. 218 r. b
TO KNOW THE NORTH SIDE OF THE MAGNET
If you wish to find the part of the magnet that naturally turns to-
wards the north get a large tub and fill it with water; and in this
water place a wooden cup and set in it the magnet without any more
water. It will remain floating in the manner of a boat, and by virtue
of its power of attraction it will immediately move in the direction of
the north star; and it will move towards this, first turning itself with
the cup in such a way that it is turned towards this star, and will then
move through the water and touch the edge of the tub with its north
side, as before mentioned. e 2 r.
This globe should be a half or a third of a braccio in diameter; and
it should be of clear glass and filled with clear water with a lamp in
the middle, with the light in about the centre of the globe, and when
suspended in the centre of a room it will give a great light.
f 23 v.
[Sphericity of water. Experiment]
A drop of dew with its perfect round affords us an opportunity of
considering some of the varied functions of the watery sphere; how it
contains within itself the body of the earth without the destruction of
the sphericity of its surface. For if first you take a cube of lead of the
size of a grain of millet, and by means of a very fine thread attached
to it you submerge it in this drop, you will perceive that the drop will
not lose any of its first roundness, although it has been increased by an
amount equal to the size of the cube which has been shut within it.
f 62 v.
[Light and heat. Sun and mirrors]
Whether the greater light with less heat causes concave mirrors to
reflect rays of more powerful heat than a body of greater heat and less
For such an experiment a lump of copper should be heated and
placed so that it may be seen through a round hole, which in size and
distance from the mirror is equal to the heated copper.
You will thus have two bodies equal in distance but differing in
heat and differing in radiance, and you will find that the greater heat
will produce a reflection of greater heat in the mirror than the afore-
We may say therefore that it is not the brightness of the sun which
warms but its natural heat.
It is proved that the sun in its nature is warm and not cold as has
already been stated.
The concave mirror although cold when it receives the rays of the
fire reflects them hotter than the fire.
A ball of glass when filled with cold water sends out from itself rays
caught from the fire which are even hotter than the fire.
From the two experiments referred to, it follows, as regards this
warmth of the rays that issue from the mirror or from the ball of
cold water, that they are warm of their own essence, and not because
the mirror or ball are hot. And in this case the same thing happens
when the sun has passed through the bodies which it warms by its
own essence. And from this it has been concluded that the sun is not
hot, whilst by the experiments referred to it has been proved that it
is extremely hot, — from the experiment which has been mentioned, of
the mirror and of the ball which being cold and taking the rays of the
heat of the fire convert them into warm rays because the primary cause
is warm. And the same thing happens with the sun, which being itself
warm, in passing through these cold mirrors reflects great heat.
f 85 v.
HOW TO MEASURE THE THINNESS OF WATER. EXPERIMENT
You will discover the various degrees of thinness of the waters by
suspending at a uniform depth of the opposite ends a strip of old
linen cloth, which should be dry, and which should penetrate on each
side as far as the bottom of two vases filled with the two different
kinds of water with which you wish to make your experiment. Then
these waters will rise a certain distance on the cloth and will proceed
gradually to evaporate, and as much as has been the evaporation of
that which has risen up, so much will it rise again from the rest until
the vase is dried up. And if you refill the vase the water will all rise
in the piece of cloth with imperceptible slowness, and so as has been
said it will gradually become dried up. And by this means the piece
will remain full of the rest of the water which has evaporated, and
in this way, by means of the weights that have been acquired, you
will be able to tell which water holds more earth in solution than the
other. g 37 v.
• OF THE SIPHON WITH MERCURY FOR MAKING FIRE
Since the more the water in the vessel diminishes the more its sur-
face is lowered, and the more the surface of the water is lowered the
less swiftly the siphon flows, but if the siphon descends at the same
time as the surface of the water that supports it, without doubt the
movement of the water which pours through will always be equal in
itself, therefore in order to make this equality let us make the vessel
n in position above the bath of mercury m. This vessel n is a boat
which supports the siphon which penetrates below from the air into
the mercury. And this mercury proceeds to rise through the siphon
n s t into the vessel /. And in proportion as the surface of this mer-
cury descends so the boat which rests upon it descends at the same
time as the siphon, which is formed of fine burnished copper and
falls into a vessel, and this when it acquires the requisite weight falls
and thereby creates fire by its impact. g 48 r.
One may finds by experiment whether if untarnishable varnish be
melted by the fire it moves from slanting positions if it is not of great
thickness, — this varnish after it has been liquefied should be smoothed
constantly with a brush. g 73 v.
[The flowing oj liquids]
If a cask is filled four braccia high with wine and throws the wine
a distance of four braccia away, when the wine has become so lowered
that it has dropped to a height of two braccia in the cask, will it also
throw the wine through the same pipe a distance of two braccia, that
is whether the fall, and the range that the pipe can throw, diminish
in equal proportion or no.
If from the cask when full two jugs are filled through the pipe in
an hour, when the cask is half full it ought for this reason to fill only
one jug in an hour, if pouring from the same pipe.
This rule with all the other similar ones about waters which are
poured through pipes ought to be put at the commencement of the
instruments, in order to be able through various rules the better to
proceed to the proofs of these instruments. 1 73  r.
[Good or poor mathematician]
In order to make trial of anyone and see whether he has a true
judgment as to the nature of weights, ask him at what point one ought
to cut one of the two equal arms of the balance so as to cause the part
cut off, attached to the extremity of its remainder, to form with pre-
cision a counterpoise to the opposite arm. The thing is never possible,
and if he gives you the position it is clear that he is a poor
mathematician. m 68 v.
Cause an hour to be divided into three thousand parts, and this you
will do by means of a clock by making the pendulum lighter or
heavier. b.m.  r.
If you wish to make a fire which shall set a large room in a blaze
without doing any harm you will proceed thus: first perfume the air
with dense smoke of incense or other strongly smelling thing, then
blow or cause to boil and reduce to steam ten pounds of brandy.
But see that the room is closed altogether, and throw powder of
varnish among the fumes and this powder will be found floating upon
the fumes; then seize a torch and enter suddenly into the room and
instantly everything will become a sheet of flame. Forster 1 43 r.
Take away that yellow surface which covers the orange and distil
it in a retort until the extract is pronounced perfect.
Close up a room thoroughly and have a brazier of copper or iron
with a fire in it, and sprinkle over it two pints of brandy a little at a
time in such a way that it may be changed into smoke. Then get
someone to come in with a light and you will see the room suddenly
wrapped in flame as though it was a flash of lightning, and it will
not do any harm to anyone. Forster 1 44 v.
[Experiment with waves of water and of air] [With figures]
Place yourself in a boat and construct an enclosure n m o p and fix
within it two pieces of board s r and t r, 1 and make a blow at a and
see whether the broken wave passes with its suitable part as far as b c:
And from the result of the experiment which you make with the
wave cut off by the circular wave of the water, may be inferred what
happens with that portion of the wave of air which passes through the
airhole through which the human voice passes when confined in a box;
as I heard at Campi from a man who had been shut up in a cask with
the bunghole left open. Quaderni in 12 v.
1 As figure shows, these two pieces of board are placed opposite to each other at
right angles to the sides of the enclosure and are each about a third of its width.
2 The lines b a, c a form an acute angle with equal arms which pass through the
ends of the two boards s r and t - and continue to the points b and c, which are near
the sides of the enclosure.