Lionardo da Vinci

Experiments

Experiments 

'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. 

785 

 

786 EXPERIMENTS 

[With drawing] 

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 
light. 

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- 
said flame. 

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 

 

EXPERIMENTS 787 

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 

 

788 EXPERIMENTS 

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 [25] 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 

 

EXPERIMENTS 789 

will do by means of a clock by making the pendulum lighter or 
heavier. b.m. [9] r. 

FIRE 

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.