Improvements in Pianos.
Year: 1893

page_text: COMPLETE SPECIFICATION.
Improvements in Pianos.
I, PETER DUFFY, a citizen of the United States, residing at No. 780 West
End Avenue New York, in the County of New York, and State of New
York, U.S.A., Inventor, do hereby declare the nature of this invention, and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
My invention is designed to provide improved devices whereby the use of bridge
pins may be avoided, and also injuries to an instrument consequent thereon, while
at the same time the tone of the instrument is improved.
In the accompanying drawings,
Figure 1 is a top plan view of a section frame plate of an upright piano, for
example, showing a number of strings in position and fastened to the sounding
board bridge by my device;
Figure 2 is a view of a portion of the plate, sounding-board bridge, and my
bridge attachment, as in use.
Referring to the figures on the drawings, 1 indicates the plate, preferably made
of cast metal, provided, as usual, with hitching pins 2, on one side, and on the
other side with tuning pins 3. 4 indicates strings passing from the hitching pins
to the tuning pins.
5 indicates a sounding board, upon which is secured in any suitable manner an
all-wood sounding board bridge 6. The sounding board bridge is connected to the
sounding board without the use of metal of any sort, so that it forms in effect a
ridge upon the board of the same material as itself, and possessing corresponding
qualities with respect to the influence upon the tone of the instrument.
In the top
of this wooden bridge is set a bearing edge, as for example, a bead 7, preferably
made of small steel wire. This bead affords a firm and equal bearing for all of the
strings and fixes their nodal points with precision; at the same time its character
is such as to impart to the tone of the instrument none of the objectionable metallic
sounds which would be incident to the employment of a metallic bridge.
8 indicates a press-bar, which in practice is of sufficient length to cover two or
more notes on the piano. It is adapted to be secured to the top of the bridge by
suitable means, as for example, screws 9 set into screw-holes 10 in the bridge,
whereby it may be adjusted. The press-bar is rounded or convex in cross section,
as indicated at 11 in the drawings and is in practice located over a corresponding
concavity 12' in the bridge. The side 13 of the bridge is considerably proportion-
ately lower than the top of the bead 7. Consequently sufficient pressure may
be exerted upon the strings by the press-bar to secure them firmly over the bead
or nodal line without bending them into the concavity of the bridge, which tends
in practice to render the strings fragile in tuning. Moreover, if the press-bar is
required to depress the string between two points into a concavity more difficulty
is experienced in obtaining the proper tension of the string. In practice the
press-bars are seldom disturbed after one adjustment. Consequently when the
tension of the string is diminished, so as to lower its tone, and the key is applied
to tune it, the resistance of the press-bar bending the string between two bearing
edges is so great as to permit that part of the string between the tuning key and
the adjacent bearing edge of the bridge--designated by the Figure 7 in this
instance-to be tuned or raised to a proper tension while that part of the string
behind the bridge, or between the bridge and the hitching pins, does not receive
the same tension. In use, however, the vibration of the instrument tends
to permit the tension from the one part to be divided with the other part, and
consequently to lower the tone.

page_text: By my invention, while I secure the advantages sought for, I confine the string
between two bearing edges, one upon the bridge, and the other upon the press-bar;
and in that manner provide for equal distribution of tension through the whole
lengths of the strings between the tuning pins and the hitching pins.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
In a piano, the combination with the frame plate, of strings and tuning pins, of
a sounding board, a bridge secured thereto, an elevated bearing upon the bridge
adjacent to the tuning pins, and a press-bar adjustably secured, vertically, behind
the bearing edges above the strings, the said strings being secured over the bridge
between two bearing edges and the strain of the strings upon the bar being in a
vertical line, substantially as and for the purpose specified.
New York, County of New York, State of New York, Fourteenth of
Jul 1893
Signed in the presence of―
W. G. TUELL.
L. J. NARBOWG.
PETER DUFFY.