From Jacques Barbeu-Dubourg
12 February 1773
Monsieur,
I found your letter to Monsieur Neave far too
short, because the excellent things it contains have made me want
to know about many other things, of which I would never perhaps
have had the slightest notion. I was never taught to swim in
childhood, and I have scarcely thought about it since. I have just
looked in the big Dictionnaire Encyclopédique, under the
words swim, swimming, etc., to find all that is said
there on the art of swimming, and I was surprised to see how little
is known on the subject. It is nevertheless a topic so interesting
for humanity that it would seem to deserve more notice from
physicists, and even from governments.
Now that I have confessed to you my ignorance,
it would be even less appropriate for me to discuss the matter than
it would be for anyone else. But I may at least be pardoned for
applying to people who are suited to discuss it, and I don’t
know anybody who is better able to do so than yourself.
I do not expect a formal treatise from you; you
have far too little leisure; but among the multitude of questions
that crowd into my mind, I beg you to cast some light on the ones
that seem especially worthy of your attention.
I will divide the questions into three
sections. The first will be devoted to a few preliminary notions,
the second to the main essential points of the art, and the third,
finally, to various consequences and other accompanying
considerations.
Section One
I. The first object, in my opinion, would be to
determine the weight of a cubic foot of ordinary water, and then
successively of water more or less cloudy, more or less saline.
Also determine the ordinary weight of the human
body, by weighing an adult male both in the air and in the water,
in order to find the average weight of a cubic foot of his body;
also weigh a woman, a child, and an old man; even weigh several
people in each category, in order to judge how much they might
differ from one another in this respect. You know what was reported
a few years ago, in the public news, about a priest from Naples
whose body (so they said) did not sink into water at all.
Perhaps men would then be found whose bodies
would float naturally in water, like most common varieties of wood,
and these men, I think, would be the most numerous. Others would be
found, fewer in number, who would float on the surface of the water
like cork, or who would sink only a little way; and still others,
even fewer in number, would immediately sink to the bottom, like
boxwood.
Try to determine, in the case of an ordinary
man, what quantity of the body’s total volume would sink into the
water, and what quantity would be supported above it.
Set about determining, as precisely as
possible, the relation between different parts of the human body,
in terms of both weight and volume. The method which would seem to
me most promising for coming close to this goal would be first to
weigh the entire body outside the water; then to weigh it again in
a large receptacle, where all the lower extremities would be
submerged and the rest of the body outside the water; then again,
with the entire trunk of the body in the water, but the head and
arms outside; next, with only the head above the water; and
finally, with the whole body underwater (which would only take a
moment). By means of a tube of the right size, adapted to the
receptacle which held the water, one would obtain the exact measure
of the quantity of water displaced by each body part. From this
measure one could determine the volume of each of the parts, and
accordingly, the relation of their volume to their weight, or what
is called their specific heaviness.
II. The second object would be to study the
particular body structure, and the different maneuvers, of the
animals who live continually in the water, or habitually spend time
there. Consequently, by drawing certain inferences, we could
discover how far it would be possible to imitate by art what
animals are led to do by instinct.
Thus tortoises walk at the water bottom, and
are able to stay there for long periods; but they are finally
obliged to come up sometimes to breathe the air. How is it that
they need to do this so rarely, while we need to do it constantly?
It is because their heart has only one ventricle, while ours has
two; between these two ventricles, in the fetus, there is an open
passageway, an oval-shaped cavity that normally closes up shortly
after birth. It does not close up in every case, however, and in
some people it is found open at quite an advanced age. It is
claimed—and this is highly likely to be true—that such people
could, like tortoises, stay for a long time underwater without
breathing; one such person, it seems, was the famous diver
Pescecola (or Nicholas the Fish), in Sicily in the fifteenth
century, who could stay two or three hours underwater. On these
grounds, it has been proposed that we should see whether we could
not procure the same advantage for any small child, by accustoming
it from birth to spending some time in the water every day, as it
did in its mother’s womb.
If this experiment appears too delicate and too
risky, there is another far simpler one, although quite cumbersome
too, about which a number of successes are reported: it consists in
providing a diver with a certain amount of fresh air, by encasing
his entire head, and even part of his body, in a sort of portable
bell. The bell should be made of an appropriate material, although
no material would be completely able to prevent an enormous
condensation of the air, thus causing great discomfort to the
lungs.
All or most fish have been equipped by nature
with a kind of aerial bladder, formed like a double pocket, which
they compress or expand at will, in order to support themselves at
different depths underwater, to descend all the way to the bottom,
or rise to the surface. Could there not be a way to imitate the
mechanism of these kinds of bladders, which would obviously be
extremely useful? Monsieur Baffert is attested to have imitated
this mechanism in some way, with a kind of pump.
All or most fish have received fins from
nature, in order to strike the water, and create a point of support
which enables them to travel in whatever direction they please.
Aquatic birds have feet adapted in such a way as to take the place
of fins; the claws are joined by membranes that open and close like
a fan, in order to provide a greater or lesser surface, and more or
less resistance to the water. Birds that lack these kinds of
membranes naturally fear the water (although their bodies are
naturally light enough to prevent them from sinking), because their
bodies have no instrument that would enable them to move about in
the water as they please. Art has imitated fins and goose feet in a
way, with the oars of boats, but since it is impossible to give
these oars the flexibility of a fan, the rower tries to make up for
it by turning the paddle of the oar now on its flat side, now on
its edge, as necessary. Goose feet are not difficult to imitate
with fan-shaped gloves, which can be made from waxed taffeta.
III. The third object would give special
consideration to which body parts are most suited to go underwater,
and which should be kept above.
Determine where the body’s center of gravity is
located, which of the body’s outer parts is closest to it, and
should therefore naturally go down first.
Since the mouth and nostrils are clearly the
body parts that it is most important to keep above water, lest
water should enter the body each time a person inhales (and should
be able to pass by that route into the stomach, the intestines and
possibly even the lungs), one should consider the various ways of
keeping the face above water, and inform people of them. The
easiest of these ways is likely to be the position on the back.
Section Two
Let us now turn to the principal object of
inquiry, namely, to what precisely constitutes the art of swimming,
and for the sake of greater clarity, let us distinguish two
essential points in that art: how to keep afloat on the water’s
surface, and how to move about as one pleases, in every direction.
Each of these points deserves to be treated separately.
I. First of all, then, it is a matter of
examining the different ways of keeping afloat on the water; or of
rising to the surface again from the bottom with the help of
additional equipment, or without any assistance, or even by
overcoming certain hindrances.
It is easy to conceive that everything able to
counterbalance the excess of our body weight in comparison to the
weight of the water should keep us on the water’s surface.
Lightweight objects firmly attached to our bodies, and poisitioned
correctly, can meet this purpose very well. Cork holds the first
place among objects of this kind, because it is naturally light and
sufficiently strong. Calabash gourds, bladders and bottles may
substitute for cork, provided that their interiors are empty, their
mouths well stopped-up, and that their sides have a sufficient
force of resistance. The diving suit of Monsieur l’Abbé de la
Chapelle (as I have been assured) is decidedly superior to
everything else of the kind, but I have heard of certain corselets,
or undervests, invented in England, which are reputed to be as good
as the Abbé’s diving suit in every respect; you are better situated
to verify this than I am.
But let us suppose a man to be left on his own,
without all of these external aids, and let us suppose him to be at
the water bottom: what resource does he have that will enable him
to rise up to the surface? He has one resource that is quite simple
and infallible. He should do precisely what he would do, if he had
his feet in the mire, in order to sink further in; he should strive
to beat the ground with his feet, and his action will not be in
vain. His feet, since they will not be able to move forward in the
direction in which he has set them moving, will be repelled with
the same degree of force in a diametrically opposite direction,
namely from the bottom upwards, and almost instantly his body will
find itself at the water’s surface.
Once he has arrived at the surface, the
question is how to stay there. We must therefore ask in what
position he first finds himself, what it is that immediately
results from this position, and what he has to do in
consequence.
He rises up to the surface in a vertical
position, his head emerging above the water. Soon, due to its
weight, the head turns down again to face the water, and as the
lower extremities of the body continue to rise, the man finds
himself stretched out at full length at water level, in a
horizontal position. In this position, the body presents its most
extensive surface to the water, and cannot sink without displacing
a very great volume of water.
The man should then exert his whole body in
order to plunge it into the water, by making all his muscles
(abdominal, pectoral, dorsal, lumbar, etc.) act in concert against
the layer of water below on which the mass of his body rests. In
the meantime the water will resist his muscles with the same force,
and by means of this reaction will support the man’s body, and will
even tend to lift him up more and more.
The method that you have conceived to
demonstrate this lesson—throwing an egg to the water bottom, and
striving promptly to remove it—is extremely ingenious, and entirely
suitable not only for inspiring people’s trust in the force of the
water, but also for teaching, without pretension, the one true and
great secret of how to benefit from this force.
Fear, in such a case, does not only prevent a
person from making the right move at the right moment, but it leads
a person to do precisely the opposite of what should be done. The
man who is frightened raises himself erect with all his might, in
order to try to rise up to the surface. As he lifts up his hands,
he strikes the water upwards from below, and is driven back in the
opposite direction, namely, downwards. As he lowers his feet, which
offer less surface area to the water than his stomach or back, his
feet act as wedges to cleave the water, and the man is soon hurled
to the bottom.
Doubtless it must be easier to swim completely
naked than burdened by clothing and other foreign bodies. Therefore
it would be a good idea to investigate what effects might result
from the constraints of clothing or from its weight; the best
expedients either for coping with this hindrance, or for getting
rid of it altogether; and finally, how much extra weight a good,
strong swimmer may or may not prudently carry, when he intends to
swim across a river.
II. Secondly, since floating on the water is
not, properly speaking, swimming, it is necessary to know how to
move one’s body in a progressive motion through the water, in
whatever direction one judges appropriate. It seems to me that this
question can easily be resolved by the same principles as the
preceding ones.
Watch a duck on a lake, and notice how, by
spreading his feet, he drives the water back, in order to be driven
forward by it, and to move himself along.
Your hands, stretched out, should point forward
with the fingers, so to speak, and strike the water with the palms
as they move close to the body. The soles of your feet, spread out,
should push the water back with force. The water ahead of you will
yield to your hands; the water behind you will react against your
feet with a force almost equal to that which you yourself used, and
you will move forward accordingly.
When you wish to change direction, it will
suffice to turn the palms of your hands and the soles of your feet
a little, and to strike the water on your right so that you will
move to the left, or on your left so that you will move to the
right.
It seems that the following could be
established as a fundamental theorem of the art of swimming: one
must move one’s feet in the water in a way exactly opposite to the
way one would move them outside the water; strike out behind with a
force that is in proportion to the speed with which one wants to
move forward; strike the water on the left to move to the right,
and on the right to move to the left; in a word, expect that every
action will be countered by the reaction of the water, put one’s
confidence in this force of repulsion, and conduct oneself
accordingly.
These principles once admitted, let us discuss
the methods that are the most convenient and the least tiring
either for staying afloat for a long time, or for swimming long
distances.
The advantages and disadvantages of various
body positions should be set parallel to each other. The two main
positions are lying on the stomach, or lying on the back as one
swims. Is the little arch that is formed underneath by the back of
any use at all? However that may be, the fact that the face is
above water when one lies on one’s back seems to be a strong reason
for preferring that position. We must also find out to what extent
this advantage can be outweighed.
Compare the respective force with which the
hands and the feet can strike the water, as well as the different
ways of using the hands and feet, and of moving them together or
separately, at the same time or in alternation, by hitting the
water or simply by pressing upon it. The feet can only help the
swimmer move forward, by striking out behind with the sole; the
hands can help support the swimmer or help him move forward,
depending on whether the palm is constantly turned downward, or
whether it is turned back.
Investigate how the swimmer can turn from back
to stomach, when he judges it appropriate, and how he can keep from
turning over involuntarily.
How long can the swimmer stay afloat when he is
sparing his strength, and what is the greatest distance he can
cover in a channel over a given amount of time?
How can the swimmer resist currents of varying
degrees of strength, and which current can he undertake to cross by
moving his arms in alternation through the water?
III. Thirdly, examine whether it is more useful
to turn sometimes onto the back and sometimes onto the stomach, or
always to maintain the same position.
What depth of water is most favorable for
swimmers, etc.?
IV. Fourthly, provide against all the accidents
that could occur in the water, such as bruises, cramps, fits of
weakness, etc.
Consider the resources that might be available
in such situations: for example, it might sometimes be of use to
walk along the water bottom, rising to the surface from time to
time both to breathe and to orient oneself.
Section Three
I. First of all, consider the pleasure of
bathing, and exercising in the water.
At what age this pleasure can be made available
to young people.
Whether it would be absurd to make it available
even to persons of the other sex.
II. Secondly, investigate the utility of the
art of swimming, and by no means ignore the disadvantages.
Whether it should constitute part of the
ordinary education of young people.
For which professions it appears especially
needful.
Whether it is not especially needful for those
in the military.
III. Thirdly, consider the salutary effects of
bathing, and of exercise in the water.
Consider the degrees of cold or warmth that
render bathing, or the exercise of swimming, more or less healthy
or unhealthy.
At what times it is appropriate to bathe.
How important it is to bathe before rather than
after a meal.
Whether one can permit oneself to consume food
or drink in the water, and if so, in what quantity.
Whether one should avoid entering the bath when
one has gotten extremely hot, and if so, what the danger is.
IV. Fourthly, consider whether it is easy to
learn to swim on one’s own, and how much easier it is to learn with
a good teacher.
How much stronger one becomes through practice
and frequent exercise.
Whether one can forget how to swim by failing
to practice it.
V. Fifthly, how to give instructions that are
simple and easy to remember for those who happen to fall into the
water without knowing how to swim.
Show those who have to travel by water, and are
exposed to these sorts of accidents, how to take inexpensive
precautions.
In particular, investigate from what material
and in what pattern clothing could be made that would be lighter
and less cumbersome in the water than the clothing that is commonly
in use.
VI. Sixthly, learn how to help a person whom
one perceives to be in danger of drowning.
What are the most effective ways of doing this,
and what are the appropriate precautions for not exposing oneself
to danger as well?
VII. Seventhly, consider the condition of
drowned persons, and the official cause of their death.
What it is that can lead one to believe these
persons are dead, when they are still alive.
What are the fastest and most powerful forms of
aid that can be given to them in such circumstances.
VIII. Eighthly, investigate everything related
to this topic in the ancient authors, and discuss whether, in the
gymnasia of the most famous peoples of antiquity, there were
instructors who taught the young people how to swim, and whether
some of their precepts have been handed down to us.
Analyze, or criticize objectively, the various
modern writings on this subject.
Find out from the travellers whether and to
what extent the art of swimming is especially cultivated in such
and such a country.
IX. Lastly, inquire into establishments that
could be created or designated for this purpose, primarily in large
cities situated upon rivers, like Paris, London, etc. The object
would be to make a large number of citizens safer from these
dangers, and to imbue everyone with greater confidence against the
very fear of these dangers, the mere idea of which makes many
people shiver.
Would not the docking area in Paris be suitable
for this purpose?
I am, etc.