IMPROVEMENTS IN PIANOS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by the said Wilhelm Fischer at the
Office of the Commissioners of Patents on the 3rd April 1882.
WILHELM FISCHER, Instrument Maker, of Dresden, Saxony, German Empire
"IMPROVEMENTS IN PIANOS "
My invention relates to pianos in which the notes are produced by forks of metal
or other suitable material, and similar to tuning-forks, and the improvements
consist in the particular mode of connecting the forks to the sounding-board of
the instrument, in the means employed for rendering their sound more pure, in a
device by which the strength of the sounds may be modulated at the will of the
player.
The connection between the forks and the sounding-board is made by means of
joints or binges. In order to keep the forks in their proper position, the movable
hinge-parts are supported or stayed by a ledge faced with a soft material, while
they are gently pressed against this ledge by a screw provided with a knob which
is faced in a similar manner. For this screw a spring, or in some cases, a weight
may be substituted. The fork may also be stayed by means of two strings or
other flexible connections fastened with one end to the movable hinge-part and
with the other to a fixed part of the piano, one, at least, of these connections being
elastic or consisting partly or entirely of a spiral spring. A modification of
the arrangement consists in employing a springing connection between the fork
and the sounding-board instead of the aforesaid hinge. With this construction the
particular means for staying the fork may be dispensed with. The purpose of
the described attachment is, to prevent the blow of the hammer on the fork from
being heard.
The second part of the invention relates to the means for improving the purity
of sound of the fork. When a tuning-fork is made to vibrate, the sound produced.

page_text: is a combination of the fundamental note of the fork and of a higher note, which
impairs the purity of sound of the former. This higher note may be suppressed
by placing a ring or band, by preference of india-rubber with felt underneath, at
a certain point around one of the prongs of the fork.
The arrangement for modulating the strength of the notes, and which forms the
third part of the invention, consists in resonance tubes in combination with a slide
by which the sound holes of the tubes may be partly or entirely closed. This slide
is connected to a pedal to be operated by the player,
'
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Wilhelm Fischer in the Great Seal Patent Office on the 2nd
October 1882.
.WILHELM FISCHER, Instrument. maker, of Dresden, Saxony, German Empire
"IMPROVEMENTS IN PIANOS."
My invention relates to pianos in which the notes are produced by forks of
metal or other suitable material, and similar to tuning-forks, and the improvements
consist in the particular mode of connecting the forks to the sounding-board of
the instrument, in the means employed for rendering their sound more pure, and
in a device by which the strength of the sounds may be modulated at the will of
the player.
On the annexed sheet of drawings Fig. 1 represents a sectional view of a piano
comprising a part of the improvements. Fig. 2 is a sectional end-view of the forks
and of parts combined therewith. Fig. 3 shows the forks and their attachment
in plan, and Fig. 4 the means employed for improving the sound of the forks.
The sounding-forks, hitherto used in pianos have always been rigidly fixed
within the same. When a fork so arranged, is struck by a hammer of the piano-
mechanism, the percussion thus caused, is always more or less audible, in
consequence whereof the musical effect of the instrument is considerably impaired.
For the purpose of remedying this deficiency, I make the connection between
the forks a and the sounding-board d by means of joints or hinges, as shown by
Figs. 1 and 3. The fork is screwed with its stem to the part n of the hinge, while
the other hinge-part, s, is fixed to the bar b attached by means of the stays c,
or in other suitable manner to the sounding-board d. In order to keep the forks
in their proper position, the hinge-parts are supported by a ledge ", which is
faced with a soft material, such as felt or leather, whereas a screw q, provided with
a knob, which is also covered with felt or leather, presses gently from above on
each of the parts n. Instead of the screw q, a spring or a weight may be used. The
fork may also be stayed by means of two strings or other flexible connections
fastened with one end to the movable hinge-part and with the other to a fixed
part of the piano, one, at least, of these connections being elastic or consisting

page_text: partly or entirely of a spiral spring. This arrangement which allows the fork
to yield to a certain amount, when it is struck by the hammer e, has proved very
efficient, not only for preventing the blow of the hammer from being heard, but
also for rendering the sound more sonorous.
According to the experiments hitherto made, it is advantageous in respect to
the quality of the sound to place the forks vertically to the sounding-board. In
case the latter is horizontal, the forks should therefore have a perpendicular
position. The arrangement of the forks parallel, or at a sharp angle to the
sounding-board, is, however, not excluded.
The part of the hinge may be made in one piece with the stem of the fork;
but I prefer to construct both hinge-parts s and n of wood, and to attach the fork
to the part n as shown in the drawing. Instead of the hinge , however, a
springing connection between the parts s and n may be employed, and, in this
case, especially when the forks are in a perpendicular position, the supports and q
may be omitted.
The second part of the invention consists in the means for improving the
purity of sound of the fork. When a tuning-fork is made to vibrate, the sound
produced is not a simple musical note, but a combination of the fundamental note
of the fork and of a higher note, (called in acoustics the harmonic,) which latter
increases in strength as the pitch of the fork becomes lower, and which in the bass-
forks even predominates over the fundamental note. This higher note, which
impairs the purity of the sound, may be suppressed by means of a ring or band o
made of, or lined with an elastic material, and placed tightly around one of the
prongs of the fork at a certain point of the same. It has been found that a ring.
of india-rubber with a piece of felt p put underneath, is particularly suitable for
this purpose. The true position of the said ring must be determined by experiment,
but generally it will have to be located at about one third of the length of the
prong from its point of union with the other prong.
.
The third part of the invention relates to the modulation of the strength of the
notes. As medium herefor I use resonance-tubes i, Figs. 1 and 2, together with
a slide m, by which their sound-holes l, Fig. 1 may simultaneously be closed more
or less.
Resonance-tubes have certainly been applied already by others for the
purpose of increasing the intensity of the sound produced by the forks; but no
means have heretofore been combined with them for varying such intensity. The
said tubes, which must be tuned in unison with the forks, are fixed above, or in
general, close to the same. When the distance between the tubes and the forks
renders it necessary, their sound-holes 7, which are opposite to the ends of the forks,
have to be provided with tubular attachments . The slide m, consisting of a
thin bar of wood or metal, or of other suitable material, is so connected with a
pedal, that it may be brought before the sound-holes or their attachments, or
shifted away from them, at the will of the player. Considering that the vibrations
of the air in the resonance-tubes are caused by the transmission of the vibrations
of the forks through the sound holes, it is evident that the former will become
fainter, the more the free area of the sound holes is reduced. The arrangement
thus affords the means, not only of producing sounds of greater or less strength,
but also of increasing or diminishing the strength of any note or chord after the
forks have been put in vibration.
The hammer-mechanism shown in the drawing presents no new features and
does therefore not require any description. Besides, any other mechanism of this
kind may be used.
By a suitable arrangement of forks tuned in the octave of those to be struck
by the hammers, it is possible to obtain in the described instrument, an effect
similar to that of the aliquot system in stringed pianos.
Having thus described the nature and object of this invention, and the manner
in which it is to be carried out in practice, I hereby claim as new and important
features of the same:
1., In pianos in which forks are employed for producing sounds, the attachment

page_text: of such forks a to the sounding-board d by means of a hinge k or a springing
connection, as and for the purpose described.
2., In combination with the forks a, attached to the sounding-board d by a
hinge or a springing connection, the supports 7 and q, substantially as hereinbefore
specified.
3., In combination with the resonance-tubes i, cooperating with the forks a,
the slide m connected with a pedal for the purpose of closing and opening the
sound-holes of the resonance-tubes, as and for the purpose specified.
་
4., In combination with a sounding-fork, a ring or band o placed tightly around
one of its prongs, for the purpose of suppressing the harmonic of the fundametal
note, as described.
In Witness whereof I, the said Wilhelm Fischer, have hereunto set my hand
and seal this twenty-fifth day of September in the year of our Lord One
thousand eight hundred and eighty two.
WILHELM FISCHER (L.s.)