IMPROVEMENTS IN PIANOS
Year: 1878

page_text: LETTERS PATENT to Etienne Constant Cadot, of Boulevard Saint Denis,
No. 1, at Paris, Manufacturer, for the Invention of "IMPROVEMENTS IN
PIANOS."
Sealed the 23rd July 1878, and dated the 31st January 1878.
PROVISIONAL SPECIFICATION left by the said Etienne Constant Cadot at
the Office of the Commissioners of Patents on the 31st January 1878:
ETIENNE CONSTANT CADOT, of Boulevard Saint Denis, No. 1, at Paris, Manu-
facturer. "IMPROVEMENTS IN PIANOS."
My Invention has for object the combination of an instrument or apparatus
destined to obviate the imperfections in the play or action of the keys of pianos,
whether arising from dampness, causing the wood to swell, which prevents their
working, or from the-weights in the keys becoming from oxidation too light, which
prevents their rising up.
My instrument or apparatus may be adapted to any kind of piano, so as to
equalize the keys, i.e., to render their play or action equal, whatever be the wear
or the reason which prevent their good working, and to cause the keys to retake
their agility, and not to become stuck or fixed.
Independently of the advantages procured by this apparatus as mechanical play,
it gives greater clearness and greater depth of sound by increasing the flexibility
of the mechanism of the hammers, which rest a shorter time on the strings, and
permit the repetition of the notes with greater facility.
The instrument or apparatus consists of a bar of wood strengthened in front by
a longitudinal right angle brass plate, and in back by a steel plate, both of which
are fixed to it by screws, so as to conjointly prevent bending of the wood. On
the under face of the longitudinal bar are cavities, equal in number to the keys of
the keyboard, and in each of them is fitted a coiled spring. Each of these springs
is held to the bottom of the cavities by a screw passing through a washer, to which
the springs are soldered or otherwise fixed. Felt washers are interposed between
the wood and the first-named washer, so as to prevent jar or vibration. At each

page_text: extremity of the longitudinal bar 'of wood is a bolt, which enters a slotted plate
provided with three slots placed one above the other.
The apparatus or instrument is placed behind the "blocks," where it is main-
tained by its two bolts. Each spring bears upon the back of each key, and forces
it to rock and rise rapidly.
More or less pressure may be applied to the springs by lowering the wooden bar
to the second slot of the slotted plate, and thus give more strength to the touch,
according to the taste and fingering of the pianist.
With this apparatus the weights ordinarily placed in the keys may be dispensed
with.
Another advantage resulting from this arrangement is to render the whole key-
board silent by placing the bolts of the wooden bar. in the third slot of the slotted
plate, and by raising or drawing back the mechanism or action of the piano.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Etienne Constant Cadot in the Great Seal Patent Office on the 26th
July 1878.
ETIENNE CONSTANT CADOT, of Boulevard Saint Denis, No. 1, at Paris, Manu-
facturer. "IMPROVEMENTS IN PIANOS."
My Invention has for object the contrivance of an apparatus, to which I give the
name of "egaliseur automatique" (automatic equaliser), and which is destined to
obviate the imperfections in the play or action of the keys of pianos, whether such
imperfections arise from dampness, having caused the wood to swell, prevent the
keys from working, or from the weights inside the keys becoming oxidized, and
therefore too light to cause them to rise up.
My apparatus, which may be adapted to pianos of all constructions, equalizes all
the keys, that is to say, it renders their play or action equal, whatever be the wear
or the cause which prevents their good working, the keys recovering their agility,
and not becoming stuck or fixed.
Independently of the advantage obtained by this apparatus as mechanical play,
it gives more clearness and more depth to the sound by increasing the flexibility
of the mechanism of the hammers, which rest a shorter time on the strings. It.
permits the repetition of the notes with greater facility, and in short, it becomes
the indispensable complement to the good working of all pianos.
The annexed Drawings illustrate the construction and working of my apparatus.
Figure 1 is a top view of a portion of a keyboard of a piano, to which my
apparatus is adapted.
Figure 2 is a side section of the same.
Figure 3 shows a front view of the apparatus applied to a keyboard.
Figure 4. is a transverse section of the apparatus on a larger scale, in order to
show its construction more clearly.
This apparatus is composed of a wooden bar a strengthened at front by a longi-
tudinal right-angled brass piece b held to it by screws. A steel plate c held behind

page_text: the bar a by screws prevents, conjointly with the angle piece, the bending of the
wood. The wooden bar a has on its under face a number of cavities or recesses d,
equal in number to those of the keys of the keyboard, and in each of which are
placed spiral springs f. Each of these springs is held to the bottom of the recesses
or cavities d by a screw passing through a washer g, to which it is soldered.
Small felt washers interposed between the wood and the washer g prevent jar or
vibration. At the two ends of the bar a is placed a bolt h, the shank of which
enters a staple or slotted plate i having three slots j, jx, and j', and seen apart at
Figure 5.
The apparatus is placed behind the blocks, where 'it is held by its two bolts h, h.
Each spring bears against the back of each key, and forces it to rock and rise
rapidly.
More or less pressure may be applied to the springs by lowering the bar to the
second slot jx, so as to give more strength to the touch, according to the taste and
the fingering of the pianist.
With this arrangement of apparatus the weights ordinarily placed in the keys
may be dispensed with.
Another advantage resulting from my apparatus is to render the whole key-
board silent, and consequently to lead to the suppression of the various small
apparatus in use, which now only render silent a portion of the keyboard.
To render the keyboard silent for its whole length the bar must be lowered to
the third slot of the staple or slotted plate, which forces the springs to exercise
great pressure on the keys, and by raising or drawing back the mechanism or
action the keys are then held, although isolated from the mechanism, and they
continue to rise up, and the whole length of the keyboard can then be played upon
without fear of any of the keys getting out of order.
All these combined advantages render my apparatus, as I have before stated, not
only the indispensable complement to all pianos working badly, owing to faulty
construction or deterioration, but also to all new.pianos, to modify the touch, and
to give to the sound a depth and pureness so difficult to obtain.
Having now described the nature of the said Invention, and in what manner
the same may be performed, I declare that I claim,—
First. The simplicity of construction of the said apparatus, permitting its adap-
tation to all kinds of pianos.
Second. The combined arrangement of pressing springs resting constantly at the
back of the keys, and forcing them to rise up, whatever be the degree of wear, or
the cause of the bad working of the keys.
Third. The means of obtaining a silent keyboard for its whole length by simply
raising or drawing back the mechanism or action.
Fourth. The facility of repetition of the notes, which are. purer and more
sonorous, this being obtained by the flexibility of the hammers resting a shorter
time on the strings.
In witness whereof, I, the said Etienne Constant Cadot, have hereunto set
my hand and seal, this Seventeenth day of July, in the year of our Lord
One thousand eight hundred and seventy-eight.
Witness,
ALBERT CAHEN,
Civil Engineer,
of Boulevard St. Denis, 1,
at Paris.
E. C. CADOT. (L.S.)