7/ you cause your ship to stop, and place the
head of a long tube in the water, and place the
other extremity to your ear, you will hear ships
at a great distance from you.'
Of the sounds that may be made in the waters as yonder from the ditch at Sant' Angelo. c.a. 65 r. a
THE NOTE OF THE ECHO
The note of the echo is either continuous or intermittent, it occurs
singly or is united, is of brief or long duration, finite or endless in
sound, immediate or far away.
It is continuous when the surface on which the echo is produced is
uniformly concave. The note of the echo is intermittent when the
place which produces it is broken and interrupted. It is single when it
is produced in one place only. It is united when it is produced in sev-
eral places. It is either brief or long-continuing, as when it goes
winding round within a bell which has been struck, or in a cistern or
other hollow space, or in clouds wherein the note recurs at fixed dis-
tances in regular intervals of time, ever uniformly growing fainter, and
is like the wave that spreads itself out in a circle over the sea.
The sound often seems to proceed from the direction of the echo, and
not from the place where the real sound is; and similarly it happened
at Ghiera d'Adda, when a fire which broke out there caused in the air
twelve lurid reflections upon twelve clouds, and the cause was not per-
ceived, c.a. 77 v. b
Whether the whole circle made in the air by the sound of a man's
voice carries with it all the word spoken, since the part of this circle
bavins struck upon another man's ear does not leave the part of this
speech in this ear but the whole:
What has been said is shown in the case of light, and you would be
able to say whether the whole of the light illumines the whole of a
building, since the part of this building would not be illumined merely
In a part of this light.
If you wish to dispute the point and say that this light illumines the
said part of the habitation not with the whole but with its part, I will
give you the instance of one or two mirrors set in different positions on
this spot, each part of this mirror will have within itself the whole of
the said light; this shows therefore that this light is all in all and all
in every part of this habitation; and it is the same with the voice in its
circle. c.a. 199 v. b
In these two rules, that is of the blow and of the force one may
employ the proportions which Pictagoras made use of in his music. 1
c.a. 267 r. a
OF THE SOUND WHICH SEEMS TO REMAIN IN THE BELL
AFTER THE STROKE
'That sound which remains or seems to remain in the bell after it has
received the stroke is not in the bell itself but in the ear of the listener,
and the ear retains within itself the image of the stroke of the bell
which it has heard, and only loses it by slow degrees, like that which
the impression of the sun creates in the eye, which only by slow de-
grees becomes lost and is no longer seen.'
A proof to the contrary
If the aforesaid proposition were true, you would not be able to cause
the sound of the bell to cease abruptly by touching it with the palm
of the hand, especially at the beginning of its strength, for surely if it
were touched it would not happen that as you touched the bell with
the hand the ear would simultaneously withhold the sound; whereas
x The reference is presumably to Pythagoras's discovery of the dependence of the
musical intervals on certain arithmetical ratios.
we see that if after the stroke has taken place the hand is placed upon
the thing which is struck the sound suddenly ceases. c.a. 332 v. a
[ Ventriloquism ]
The ear is deceived by the perspective of the voice which seems to
send itself to a distance and does not change its position.
c.a. 357 v. b
If a man jumps on the points of his feet his weight does not make
any sound. Tr. 5 a
I ask whether a slight sound close at hand can seem as loud as a big
sound afar off. Tr. 12 a
THE NATURE OF THE EFFECT OF THE ROAR OF THE
The rumbling of the cannon is caused by the impetuous fury of the
flame beaten back by the resisting air, and that quantity of the powder
causes this effect because it finds itself ignited within the body of the
cannon; and not perceiving itself in a place that has capacity for it to
increase, nature guides it to search with fury a place suitable for its
increase, and breaking or driving before it the weaker obstacle it wins
its way into the spacious air; and this not being capable of escaping
with the speed with which it is attacked, because the fire is more
volatile than the air, it follows that as the air is not equally volatile with
the fire it cannot make way for it with that velocity and swiftness with
which the fire assails it, and therefore it happens that there is resistance,
and the resistance is the cause of a great roar and rumbling of the
But if the cannon were to be moved against the oncoming of an im-
petuous wind it would be the occasion of a greater roar made by reason
of the greater resistance of the air against the flame, and so it would
make a less rumbling when moved in the line of the wind because
there would then be less resistance.
In marshy places or other wide tracts of air the cannon will make a
louder report close at hand, and at a lesser distance it will be perceived
that up on the mountains or in other places where the air is rarefied, if
the air be thick or thin equally and without direct movement of winds,
the roar will be equally perceptible round about its cause, and it would
io on expanding from circle to circle just as the circles of water do
when caused by a stone thrown into it; and in that place where
similar instrumenti are being used the adjacent air will break or scatter
all the things of weak power of resistance. All the large vessels with
wide mouths will become broken, the windows of paper and such like
things; the neighbouring roofs will all be shaken on their supports;
and this will take place though many windows and doors stand open,
and walls which are thin and without buttresses will become dan-
This happens because the air swells and presses itself out and wishes
to escape in all directions in which movement is possible. Doors win-
dows trees and such things as these will all be moved, and if you set
an arrow lightly fastened with a small stone it will be carried about a
distance of six miles through the movement of the air. Tr. 44 a
WHAT THING IS SOUND CAUSED BY THE BLOW?
The time in which the blow is produced is the shortest thing that can
be done by man, and no body is so great but that being suspended it
makes an instant movement at a sudden blow; which movement beats
back in the air and the air sounds as it touches the thing moved.
WHETHER THE SOUND LIES IN THE HAMMER OR IN
I say that because the anvil is not suspended it cannot resound. The
hammer resounds in the jump that it makes after the blow, and if the
anvil were to re-echo the sound made on it by every small hammer as
does the bell with every different thing which strikes it with the same
depth of tone, so would the anvil when struck by each different ham-
mer; and as therefore you hear different notes with hammers of dif-
ferent sizes it follows that the note is in the hammer and not in the
Why the thing which is not suspended does not sound and when
suspended every slight contact takes away the sound from it:
The bell when struck makes a sudden tremor and the sudden tremor
causes it instantly to strike the circumscribing air, which instantly
On being impeded by any slight contact it does not make the tremor
or strike and so the air does not resound.
If the bird suddenly beats the air ought this to resound or no:
I maintain it does not because as the air penetrates through the thing
that beats it it does not receive the blow and consequently it cannot
OF THE BOMBARD OR ARROW
Here sounds movement of air more powerful than the resisting air.
Tr. 64 a
I say that every body moved or struck keeps in itself for a time the
nature of this blow or movement, and keeps it so much more or less
in proportion as the power of the force of this blow or movement is
greater or less.
Observe a blow given on a bell how much it preserves in itself the
noise of the percussion.
Observe a stone projected from a bombard how much it preserves
the nature of the movement.
The blow given on a thick body will keep its sound longer than on
a thin body, and that will be of longest duration which is made upon a
body that is suspended and thin. The eye keeps within itself the
images of luminous bodies for a certain interval of time. Tr. 73 a
It is possible to recognise by the ear the distance of a clap of thunder,
on first seeing its flash, from its resemblance to the note of the echo.
The voice is all in all and all in the part of the wall surface where it
strikes. And that part which is formed in such a way as to be fitted to
send back the percussion, gives back the voice in as many different
small portions of itself as there are different positions of the hearers.
The ear receives the images of sounds by straight curved and broken
lines and no twists can break its function. a 19 r.
The voice after it has struck on the object will return to the ear by a
line at a slant equal to that of the line of the incidence; that is the line
which carries the voice from its cause to the place where this voice can
reform itself; and this voice acts in the manner of a thing seen in a
mirror which is all in all the mirror and all in the part of it. Let us say
therefore that the mirror is a b and the thing seen is c; just as c sees
all the parts of the mirror so all the parts of the mirror see c; there-
fore c is all in all the mirror because it is in all its parts; and it is all
in the parts because it sees itself in as many different parts as there are
different positions of spectators . . .
Let us take the sun as an example: if you should walk along the
bank of a river and watch the sun's reflection in it, for so long a time
as you walk along the bank of the river it will seem that the sun moves
with you, and this because the sun is all in the whole and all in the
part. a 19 v.
OF A BLOW
The blow given in the bell leaves its likeness behind it impressed as
is that of the sun in the eye or the scent in the air; but we wish to dis-
cern whether the likeness of the blow remains in the bell or in the air,
and this is ascertained by placing your ear to the surface of the bell
after the blow.
The blow given in the bell will cause a slight sound and movement
in another bell similar to itself, and the chord of a lute as it sounds
produces movement and response in another similar chord of like tone
in another lute, and this you will perceive by placing a straw upon the
chord similar to that which has sounded. a 22 v.
OF THE VOICE
Whether many tiny voices joined together will make as much sound
as one large one. I maintain they will not; for if you were to take ten
thousand voices of flies all together they would not carry as far as the
voice of a man, and if such voice of a man were split up into ten
thousand parts no one of these parts would be equal to the size of the
voice of a fly. a 23 r.
Whether a sound that is double another will be heard twice as far.
I maintain that it will not for if it were so two men shouting would be
heard twice as far as one; but experience does not confirm this.
a 43 r.
If you cause your ship to stop, and place the head of a long tube in
the water, and place the other extremity to your ear, you will hear ships
at a great distance from you.
You can also do the same by placing the head of the tube upon
the ground, and you will then hear anyone passing at a distance from
you. b 6 r.
[Of the echo]
The voice after having proceeded from the man and having been
beaten back by the wall will fly upwards. If there be a ledge above this
wall with a right angle the surface above will send back the voice
towards its cause.
How one should make the voice of the echo which whatever thing
you may say will be repeated to you in many voices :
Braccia one hundred and fifty from one wall to the other.
The voice which issues forth from the horn forms itself on the op-
posite wall and from there leaps back to the second, and from the
second [it returns] to the first, as a ball that rebounds between two
walls which diminishes its bounds; and so the voices grow less.
b 90 v.
OF THE SOUND MADE BY PERCUSSION
Sound cannot be heard at such close proximity to the ear that the
eye does not first see the contact of the blow, and the reason is this : —
if we admit that the time of the blow is indivisible, that the nature of
the blow does not produce its expansion upon the body which has been
struck without time, that no body struck can resound whilst the thing
1h.1t strikes is touching it, and that the sound cannot travel from the
body struck to the ear without time, then you must admit that the
thing which strikes is separated and divided from the thing struck be-
fore this thing struck can of itself have any resonance; and not having
this it cannot give it to the ear. c 6 v.
OF REFLEX MOVEMENTS
I wish to define why bodily and spiritual movements after the per-
cussion made by them upon the object spring back within equal angles.
OF BODILY MOVEMENTS
I say that the note of the echo is cast back to the ear after it has
struck, just as the images of objects strike the mirror and are thence
reflected to the eye. And in the same way as these images fall from the
object to the mirror and from the mirror to the eye at equal angles, so
the note of the echo will strike and rebound within the hollow where
it has first struck, at equal angles to the ear. c 16 r.
Why the swift wind which passes through a reed makes a shrill
The wind passing through the same reed will make a sound so much
deeper or shriller in proportion as it is slower or swifter. And this is
seen in the changes in the sounds made by trumpets or horns without
holes and also in the winds that howl in the chinks of doors or win-
dows. This originates in the air, where the sound having issued forth
from the instrument traverses the valley and proceeds to spread itself
in a greater or less degree according as the air is driven by a greater
or smaller force. This may be proved. e 4 v.
Why the reflex movement of the stone makes more noise in the air
than its incidental movement, the reflex movement being less powerful
than the incidental, and whether this reflex movement makes a greater
or less sound as the angle of its incidence is more or less obtuse. But as
regards the first question the reflex movement is made by the composite
movement of this projectile, and the incidental movement is made by
the same movement of the same projectile; and for this reason the
sound is in the reflex movement of the projectile and not in the inci-
dental movement. As regards the second question in proportion as the
angle is more obtuse the projectile is more disposed to revolve than
when the percussion is made between acute angles. e 28 v.
The sound caused by the wind or by a blow will grow fainter when
as a result of time or distance it is further removed from its cause.
The stroke given to the bell will go on growing less as more time
passes and it is the same whether the distance is far or near.
H 72  V.
[Of separated forces: — rivers, bells, ropes]
Of dividing the force of rivers:
If the excessive size of the rivers damages and destroys the sea coasts,
then if such rivers cannot be diverted to other places they should be
parted into small streams.
If a bell which sounds is heard at six miles and weighs six thousand
pounds, six miles being eighteen thousand braccia . . . But not to ex-
tend myself in too many arguments I maintain that if I were to split
it up into tiny bells it will not be heard at an eighth of a mile even
though all the metal rings in the bells at the same time.
Similarly if a rope supports a hundred thousand ounces and you
separate it into a hundred thousand strands, each strand of itself will
not support one eighth part of an ounce. And so it follows with all the
separated powers. 1 in  r.
SOUND OF THE ECHO
If the sound of the echo answers in two divisions of time at thirty
braccia, in how many divisions will it answer if it is a hundred braccia
If the sound of the echo answers me in two divisions of time at a
distance of thirty braccia, with two degrees of power in its noise, with
how many degrees of noise will it reveal itself to me at a distance of a
hundred braccia? 1 129 [81 J v.
[Sottnd — laws of]
Why will the deep-toned vessel with contracted mouth have a much
deeper and lower sound in its percussion when it has a narrow mouth
than when it is wide? l 63 r.
How the sound of the voice is lost by reason of distance:
[ With (I ia gram]
At the distance a b the two voices m n are diminished by half; con-
sequently although there are two half voices they are not as powerful
as one whole voice but merely as a half.
And if an infinite number of halves should find themselves at such
distance they would only amount to a half.
And at the same distance the voice / which is double n and m hav-
ing lost the fourth part of its power remains consequently as a voice
and a half, and surpasses in three times the power, so that at three
times the distance, that is at g, f will be as powerful as m n are at the
distance a b. l 79 v.
[Voice in distance]
Where one voice does not carry, a multiple however great made up
of voices equal to the aforesaid will not carry. l 80 r.
[Noise of the mortar]
One proves by this example how the noise made by the mortar
(bombarda) is nothing but a separation of compressed air. l 89 v.
[Sound of bombards — how produced]
The wave of the flame created by the setting fire to the powder of
the bombards is that which striking the air opposite to it creates the
sound. m 82 r.
If flies made with their mouths the sound that is heard when they
fly then since it is very long and sustained they would need a great pair
of bellows for lungs in order to drive out so great and so long a wind,
and then there would be a long silence in order to draw into them-
selves an equal volume of air; therefore where there was a long dura-
tion of sound there would be a long intermission. b.m. 257 v.
If a bell were to be heard with its sound two miles, and then it were
to be melted down and cast again into a number of small bells, cer-
tainly if they are all sounded at one time they will never be heard at
as great a distance as when they were all in one bell.
Forster 11 32 v.
If you make two bells of the same shape and the one double the size
of the other but of the same weight the larger will have twice the depth
of tone. Forster in 5 r.
[Of the buzzing of flies]
That the sound which flies make proceeds from their wings you will
see by cutting them a little, or better still by smearing them a little with
honey in such a way as not entirely to prevent them from flying, and
you will see that the sound made by the movement of the wings will
become hoarse and the note will change from high to deep to just the
same degree as it has lost the free use of its wings. Fogli a 15 v.