IMPROVEMENTS IN PIANOFortes
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by the said Wilhelm Fischer at the Office
of the Commissioners of Patents on the 18th November 1882.
WILHELM FISCHER, resident in Leipsic, Kingdom of Saxony, German Empire,
"IMPROVEMENTS IN PIANOFortes
دو
This invention consists in improvements in the pianos described in the specifi-
cation of the British letters patent A.D. 1882 No. 1603, and in which the notes
are produced by sounding-forks.
By continued experiments I have found that the forks, when they are fixed to
the sounding-board, have a prejudicial influence on each other, inasmuch as their
sound, however full and sonorous it may be when there are but few forks in
the instrument, will be considerably reduced in strength, when the whole series is
secured to the board.
In order to remove this defect, I at present attach the forks to a bar which is
independent of the sounding-board, and I establish a contact between them and
the latter separately for each fork at the moment it is struck by the hammer, and
for the time only that its sound is desired to be heard.
This contact is produced by means of a piece which may be called the trans-
mitter, and which is adapted to convey the vibrations of the fork to the sounding-
board.
The said transmitter is so operated by the key of the note to which it belongs,
that by the depression of the key it will be brought to bear against a ledge on the
sounding-board and against the stem of the fork or some part connected therewith.
If preferred the transmitter may be attached with one end to the sounding-board
or to the fork. In this case it must be made elastic so as to allow its other end to
be raised as required.
The second part of the invention relates to the suppression of the secondary or
harmonic note of the forks. This is attained by making one prong of the forks
thicker than the other one.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Wilhelm Fischer in the Great Seal Patent Office on the 9th May
1883.
WILHELM FISCHER, resident in Leipsic, Kingdom of Saxony, German Empire
"IMPROVEMENTS IN PIANOFORTES
"
This invention consists in improvements in the pianos described in the specifi-
cation of the British letters patent A.D. 1882 No. 1603, and in which the notes
are produced by sounding forks.
By continued experiments I have found that the forks, when a greater number
of them is fixed to the sounding board, have a prejudicial influence on each other,
inasmuch as their sound, however full and sonorous it may be when there are but
few forks in the instrument, will be considerably reduced in strength, after the
whole series has been secured to the board.
In order to remove this defect I at present attach the forks to a bar which is
independent of the sounding board, and I establish a contact between them and the
latter separately for each fork at the moment it is struck by the hammer and for
the time only that its sound is desired to be heard. This contact is produced by
means of a piece which I have called the transmitter, and which is adapted to
convey the vibrations of the fork to the sounding board.
The said transmitter is so operated by the key of the note to which it belongs,
that by the depression of the key it will be brought to bear against a ledge on the.
sounding board and against the stem of the fork or some part connected therewith.
If preferred the transmitter may be attached with one end to the sounding board
or to the fork. In this case it must be made elastic so as to allow its other end to
be raised as required.
The second part of the invention relates to the suppression of the secondary or
harmonic note of the forks. This is attained by making one prong of the forks
thicker than the other one.
The invention is represented on the annexed sheet of drawings in Figs. 1 and 2
in two different arrangements. Fig. 3 shows a modification of a part thereof,
while Fig. 4 is a fork embodying an improvement by which greater purity of tone
is attained.
The forks a are carried by a bar b consisting of lead strengthened by a core of
To this
iron, or of any other suitable material being a bad conductor of sound.
bar the forks may be fixed directly with their stem; but by preference the attach-
ment is made by means of a hinge k and an arm i, as shown in Figs. 1 and 2, the
fork being at the same time held between two screws q and r having knobs faced
with soft material, or in other convenient manner. In order to reduce the trans-
mission of vibrations from the forks to the bar b, the arms i are, with advantage,
made of two parts between which a piece of india-rubber or felt, &c., is inserted,
as represented by Fig. 3. m is the intermediate piece or transmitter, by which the
temporary contact between a fork struck by its hammer and the sounding board d
is established. The same is fixed, according to Fig. 1, with one end to the ledge c
of the said board d.. In its position of rest this piece does not touch the fork or
the hinge-part 8; but it is sufficiently elastic that, when the key f is depressed,
the pin or lifter g will press its free end against the stem of the fork, or the part 8,
as the case may be, and thus produce the contact requisite for the transmission of
the vibrations. This contact is maintained as long as the key is depressed, and is
broken when the latter is released. If preferred the transmitter may be attached
to, or form one piece with the binge-part 8, while it is arranged to be brought in

page_text: and out of contact with the ledge c.
According to the drawing the lifter g is
operated by a lever h acted upon by the key f. The purpose of this lever is to
reduce the stroke of the lifter which would be disadvantageously great if the latter
were connected to the end of the key.
In the modification represented by Fig. 2 the transmitter forms the head of the
lifter g and is so arranged that, when raised by the key, it will simultaneously
touch the ledge c and the fork-stem or the hinge-part 8.
According to my aforesaid former specification the secondary or harmonic note
of sounding forks is suppressed by means of an elastic ring placed around one of
the prongs of the fork. The same effect may be obtained by making one prong of
the fork thicker than the other one, as is shown in Fig. 4. Another medium for
attaining the same purpose consists in drilling a hole into the fork at the point
where the prongs unite with the stem, and in filling this hole with lead or other
soft metal, or with india rubber, (see Fig. 5).
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 a piano in which the notes are produced by sounding forks, the attach-
ment of the forks a to a bar b independent of the sounding board, and the
transmitter m, which, upon being lifted by the key f, establishes contact between
the fork and the sounding board, substantially as and for the purpose described.
2., In a piano with sounding forks, the use of forks one prong whereof is thicker
than the other, as and for the purpose specified.
In Witness whereof I, the said Wilhelm Fischer, have hereunto set my hand
and seal this twenty-fifth day of April in the year of our Lord One
thousand eight hundred and eighty-three.
WILHELM FISCHER (L.S.)