IMPROVEMENTS IN PIANO- FORTES.
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by George Frederick Redfern at the Office
of the Commissioners of Patents on the 12th October 1878. A communi-
cation from abroad by George Caddick, of Allegheny, Pennsylvania, United
States of America.
GEORGE FREDERICK REDFERN, of the General Patent Office, 4, South Street,
Finsbury, in the County of Middlesex, Patent Agent. "IMPROVEMENTS IN PIANO-
FORTES. A communication from abroad by George Caddick, of Allegheny, Penn-
sylvania, United States of America.
"
These improvements relate to upright pianofortes, and consist in a number of
tubes or bars composed of iron, steel, or other metal with screw-threaded sockets
on their ends. These are placed between the sound board and strings of the
instrument, pass through the bridge, and abut against the wrest-plank and plate-
plank, having a metal bearing-bar provided either with bosses to receive the ends
of the tubes or equivalent devices intervening between the ends of the tubes and
said wrest and plate planks. The tubes serve to resist the pull of the strings, and
also to distend the sound board.
The object of the Invention is to obtain a light yet staunch resistance to the pull
of the strings, and to provide a means of regulating the sound board to its proper
tension, so as to produce the best volume and quality of sound, which is accom-
plished by adjusting the screw-threaded sockets on the tubes until the desired
distension of the sound board is produced. After this distending the plate plank is
secured to the frame.
The method of distending may be after the sound board is inserted into the
wrest plank and plate plank, and before securing the same to the back frame; or
secure the wrest plank to the frame, insert the lower edge of the sound board into
the groove in the plate plank, place in the tubes, then insert the upper edge of the
sound board into the wrest plank, and distend the same before securing the plate
plank to the frame.
A number of screw-threaded pins are screwed through the iron plate and into
the tubes, and while the pins hold the iron plate at the proper distance from the
tubes, the tubes are thereby kept straight, and will the better resist the strain.

page_text: By the above arrangement of the pins it is apparent that a proportion of the pull
of the strings is transmitted to the tubes, whereby a much lighter iron plate may
be used than heretofore, which will very materially reduce the weight of the
piano.
It is evident that the tubes being placed between the sound board and strings
act as a centre, so that the pull of the strings maintains the distention of the sound
board against extension and contraction by atmospheric changes.
It will
By these improvements there is no deflection or sinking of the sound board, as
the pressure of the strings on the bridge bears down on the tubes (preventing any
rattle), whilst the pull of the strings from the iron plate hold up the tubes; thus
the strain is counterbalanced, leaving the sound board free to vibrate.
be seen that the wrought-iron tubes being under pressure gives them a particular
ringing sound, and passing tight through the bridge the live metallic vibrations
are combined with the elastic tones from the sound board, thus producing that
beautiful singing and sonorous tone so much to be desired in the art of pianoforte
making.