IMPROVEMENTS IN THE SOUND-BOARDS OF PIANOFORTES to be ass
Year: 1884

page_text: I JOSEPH DELERUE of No 240 rue Cedofeida, Porto, in the Kingdom of Portugal,
Piano-forte Manufacture do hereby declare the nature of the said invention for
"IMPROVEMENTS IN THE SOUND-BOARDS OF PIANOFORTES to be as follows:-
"
My invention consists in fixing the sound board to the framing of the piano in
such a manner that it shall be more free to vibrate than by.the present mode of
construction.
For this purpose I fix the sound board by means of a thin rail or slip passing
round the sound board at a short distance from its edges so as to leave the
projecting edges free to vibrate without being supported.
The rail or slip is glued or fixed in grooves made in the framing of the piano,
and in the sound board.
I JOSEPH DELERUE of No 240 rue Cedofeida, Porto, in the Kingdom of Portugal,
Piano-forte Manufacturer do hereby declare the nature of the said invention for
"IMPROVEMENTS IN THE SOUND BOARDS OF PIANO-FORTES " and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement:-
My invention consists in fixing the sound board to the framing of the piano in
such a manner that it shall be more free to vibrate than by the present mode of
construction.
For this purpose I fix the sound board by means of a thin rail or slip passing
round the sound board at a short distance from its edges so as to leave the
projecting edges free to vibrate without being supported.
The rail or slip is glued or fixed in grooves made in the framing of the piano,
And in the sound board.

page_text: In order to enable my invention to be fully understood I will proceed to describe
the same by reference to the accompanying drawing which represents a section of
the framing of a pianoforte illustrating my invention.
F, F, is the sound board provided with its bridge T; the sound board is fixed to
or supported on the framing. O, of the pianoforte by means of the thin rail or
slip H, H, passing round the sound board at a distance from its edge which may
vary from about one to ten centimeters; the support H H of the sound board
consists of a thin strip of wood about three to four millimeters in thickness; it is
fixed in grooves made in the framing O, of the pianoforte and in the sound
board F.
In this arrangement I have applied a well known principle; the resonance of a
sound board is caused by its own vibration; the result of investigation of these
vibrations has been the discovery of peculiar phenomena known in acoustics as
nodes or nodal points and loops or ventral segments.
In all bodies when vibrating a certain number of points remain always at rest
and serve as points of support to the movements of the whole body. It is these
movements of vibration which produce the nodes and loops as well as nodal lines.
The seat of the vibrations necessitates absolute, independence of the resonant
bodies without which there is no sensitiveness in consequence of the inertia to be.
overcome. On the other hand there is a no less absolute necessity for a thorough
fixidness of the resonant bodies without which interferences will occur from
vibrations which will counteract the effect of these vibrations as is the case in
luminous phenomena.
'
I have for the foregoing reasons applied to the sound boards of pianofortes the
herein before described continuous strip leaving the edges free so that the board
fixed to the framing by means of the said strip can. vibrate with greater
sonorousness whilst being supported thereby and its edges project at distances
which may vary and which are determined by experience.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is :-
Fixing the sound boards of pianofortes to the framing thereof by means of a
continuous strip extending round the sound board at a suitable distance from its
edges as hereinbefore described.
Dated the 10th day of November 1884.
G. F. REDFERN,
4, South Street, Finsbury, London,
Agent for the Applicant.