Jean-Frédéric Leschot and his famous
prostheses
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Along
with constructing androids, automaton clocks and mechanical
birds, the Jaquet-Drozes and their partner Jean-Frédéric Leschot
took to making prostheses which skilfully replaced amputed limbs.
Jean-Frédéric Leschot specialized in this activity.
His reputation in this field brought him numerous orders from many foreign
countries. |
Jean-Frédéric Leschot
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We must admit that he took advantage of
his watchmaking knowledge to make active prostheses
whereas the best doctors of that time used to make passive
prostheses. These were made only for an aesthetic purpose
whereas Leschot's prostheses allowed usual objects
to be seized and manipulated in a way that no one knew that
they existed. (In the film "The Jaquet-Droz androids
— on sale on this website—a prosthesis
is reassembled according to the descriptions given by Jean
- Frédéric Leschot.) |
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Chapuis and Gellis, the authors
of Le Monde des automates (The world of the automatons)
wrote: "We reproduced a note from the 1792 Newspaper of watchmaking
detailing the different parts of an artificial arm according to
gravity. It is an interesting document for it presents the materials
used, the accuracy of each organ's weight" : |
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PROSTHESIS DETAIL
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PROSTHESIS WEIGHT
(French measures of that time)
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| The elbow joint with all its steel
parts |
2 onces 8 deniers 18 grams
|
| Leather covering the stump from
the shoulder to the elbow joint. |
4 on. 10 den. 18 grs.
|
| The wrist joint including the
steel trigger part fixed at the joint with the wire link. |
8 den.
|
| The arm made of cardboard and
parchment from the elbow to the wrist joint. |
3 on. 22 den. 5 grs.
|
| The cork wrist with spring and
cylinder as well as the finger-bearer anchored to the wrist. |
2 on. 4 den. 15 grs.
|
| The whole thumb with steel strips
anchored inside for both joints. |
17 den. 4 grs.
|
| The finger, mounted the same way
with all the parts and the nut. |
10 den. 21grs.
|
| The middle finger, mounted as
above. |
14 den. 3 grs.
|
| The ring finger, mounted as above. |
9 den. 16 grs.
|
| The little finger, mounted as
above |
7 den. 15 grs.
|
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TOTAL WEIGHT OF THE PROSTHESIS
|
16 on. 3 den. 19 grs.
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The writer's hands
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The weight of the artificial arm was about 480
grams. It is obvious that this prosthesis had to be
well studied in order to be that light. |
The draftsman's hands
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Finally we must demonstrate
how the clockmaking techniques allowed J-F. Leschot to make
such functional prostheses and artificial limbs.
In their book The Jaquet-Drozes and Leschot,
Charles Perregaux and F.-Louis Perrot wrote:
"In a letter addressed to Mr de Luze-Bethmann in 1795, Leschot
explained the mechanism of the wooden and iron limbs for Mr de Luze
had ordered a left arm for the Baroness Strakham from Frankfurt.
Leschot replied: "I am in a position to fulfill your
request. Many items of this kind have already been entrusted to
me by people who were always satisfied and relieved. A few years
ago I made an artificial arm for a young lady whose arm had been
amputed almost up to the shoulder and it is very useful to her and
nothing shows when she is dressed." |
Arm prosthesis made by
Ambroise Paré
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Then Leschot asked that a mold of
the Baroness'right arm and hand be sent to him. On this model
the size and "embankment" of the amputation had
to be written. The stump shape thus known, Leschot
was able to drive and adapt the artificial limb to it. |
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According to Leschot,
the mechanism which is very mobile at the elbow joint as well as
the other parts allowing the following functions shall be so well
fixed that the artificial arm shall obey the lady's will of movement.
And about the right hand, he let us also know that:
"In the hollow of the mechanical hand I have
installed a trigger hidden in a glove that she always must have and
which is easy to change. When she slightly pulls the trigger with the
right hand's palm, the elbow hinge releases, which enables her to raise
or pull down the artificial arm from its former position and in a fixed
way at the required level of any desired movement."
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Artificial arm by Kriegeissein
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"Then, she rotates the arm from left
to right as well as the wrist, that is to say the hand which moves
around the joint, giving the required attitude to the arm. The
fingers have three joints too which can move separately in the
case that she wants to hold something in this hand, giving them
a natural driving to held such a thing. It is to notice that only
the thumb has a pressure power against the second finger, it is
thus used to pinch or seize light or small objects such as a card,
a knitting needle, and so on... |
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The elbow joint is particularly useful in winter
for instance when one has a muff. Such objects could be held while
the right arm would be free or used for any other object or movement..."
Such an artificial limb cost 50 Louis.
Left hand of the female musician
by the Jaquet-Drozes
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