Improvements in Piano-fortes.
Year: 1891

page_text: Date of Application, 27th July, 1891
Complete Specification Left, 26th Apr.. 1892-Accepted, 27th July, 1892
PROVISIONAL SPECIFICATION.
Improvements in Piano-fortes.
I, GEORGE CADDICK of Church Avenue near Maddison Avenue Alleghany
City, United States of America, Piano Tuner, do hereby declare the nature of this
invention to be as follows:-
It is a known principle in acoustics that if a tuning-fork of a certain pitch be put
in vibration and held to the mouth of an organ pipe whose tone corresponds to the
tuning-fork in pitch the pipe will be put in vibration and will produce a sound of
the same pitch as the tuning-fork being in exact relation to the air in the pipe, and
that if a tuning-fork be put in vibration and set on a hollow tube or box open at the
end and containing the relative cubic inches of air required in a pipe to produce a
sound of the same pitch as the tuning-fork the tone of the fork will be augmented
and modified by the vibrations imparted to the air in the tube. These principles
are embodied in my improved apparatus, which I will now proceed to describe, and
which consists in combining with the strings of a piano air tubes of corresponding
pitch, which are adapted to respond thereto.
In the application of the invention I prefer to construct the tubes by partitioning
the space between the sound board and the back-frame board, by which means I. am
enabled to support the strings out of line on an elevated bridge set on the sound-
board, thereby obtaining a more solid bearing of the strings on the bridge and
imparting their full vibration to the sound-board and underlying flue-pipes. These
partitions consist preferably of interposed wooden strips glued to the back-frame
and sound-board, thus forming flues or pipes, which may be made of exactly the
size and proportion required, and which are preferably open at the end nearest the
wrest plank and closed at the end nearest the bridge though if desired, the openings
may be formed next to the bridge and the closed ends situate at the wrest plank.
I prefer the construction first named, because I am thereby enabled to obtain much
better results than if the closed ends are at the wrest-plank. A sound-board thus
constructed does not require any ribs, because the partitions forming the flues or
pipes answer the same purpose and impart to the structure strength sufficient to
support the bridge. It is not only requisite that the tube shall contain the number
of cubic inches of air necessary to produce the tone needed, but that the open end of
the pipe shall be of proper proportion, and I find I obtain the best result when the
area of the opening is the fifty seventh or one hundred and fifteenth part of the area
of the interior of the pipe.
The air spaces of the tubes may be calculated to the simplest relative sound-
such as octaves, fifths, and fourths, adding the thirds where the space will admit of
it-leaving the remaining tones to vibrate in sympathy with them. The tubes
respond by sympathetic vibration and are scaled similar to organ pipes to proper
Jengths and breadths. For the treble and middle strings of the piano I employ a
tube for each set of strings or tone arranged according to the chromatic scale,
except that for the last octave I may omit the partitions altogether.
It is not absolutely necessary for the tubes to be immediately under the set of
strings to which they respond, as I find they will respond if some distance away
but it is desirable to have them placed as near to the strings they belong as the
scale of the piano will admit.
In
My invention may be applied either to upright or grand pianos, and its advan-
tages in securing fulness of tone will be appreciated by the skilled musician.
pianos of the construction heretofore employed there has always been difficulty
experienced in that the sound-board in time loses its elasticity, thereby injuriously
affecting the tone of the piano. In my improved construction where the air-tubes

page_text: take the place of the sound-board, this cannot happen. I am also enabled by the
use of the partitions to obtain a strong support for the bridges, and thereby to
prevent the evil consequences resulting from sinking of the bridge away from the
strings.
DL1. 1
C T 1
1001
COMPLETE SPECIFICATION.
Improvements in Piano-fortes.
I GEORGE CADDICK of Church Avenue, near Maddison Avenue, Alleghany
City United States of America Piano Tuner, 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 :-
Fig. 1 is a plan view of the sound board of the piano provided with my improve-
ments.
Fig. 2 is a cross section on the line II II of Fig. 1.
Fig. 3 is a vertical section on the line IV IV of Fig. 1.
Like symbols of reference indicate like parts in each of the figures.
It is a known principle in acoustics that if a tuning fork, of a certain pitch be
put in vibration and held to the mouth of an organpipe whose tone corresponds to
the tuning fork in pitch the pipe will be put in vibration and will produce a sound
of the same pitch as the tuning fork, the vibration of the tuning fork being in
exact relation to the air in the pipe and that if a tuning fork be put in vibration
and set on a hollow tube or box open at the end and containing the cubic inches of
air required in a pipe to produce a sound of the same pitch as the tuning fork, the
tone of the fork will be augmented and modified by the vibrations imparted to the
air in the tube. These principles are embodied in my improved apparatus which I
will now proceed to describe and which consists in combining with the strings of a
piano air tubes of corresponding pitch which are adapted to respond thereto.
In the application of the invention I prefer to construct the tubes 'by partitioning
the space between the sound board and the backframe board by which means 'I am
enabled to support the strings out of line on an elevated bridge set on the sound
board thereby obtaining a more solid bearing of the strings on the bridge and
imparting their full vibration to the sound-board and underlying flue-pipes. These
partitions consist preferably of interposed wooden strips glued to the back frame
and sound board thus forming flues or pipes which may be made of exactly the
size and proportion required and which are preferably open at the end nearest the
wrest-plank and closed at the end nearest the bridge though if desired the openings
may be formed next to the bridge and the closed ends situate at the wrest-plank.
prefer the construction first named because I am thereby enabled to obtain much
better results than if the closed ends are at the wrest-plank. A sound board thus
constructed does not require any ribs because the partitions forming the flues or
pipes answer the same purpose and impart to the structure strength sufficient to
support the bridge.
It is not only requisite that the tubes shall contain the number of cubic inches of
air necessary to produce the tone needed but that the open end of the pipe shall be
of proper proportion and I find I obtain the best result when the area of the
opening is the fifty-seventh or one hundred and fifteenth part of the area of the
interior of the pipe.
Referring to the drawings
A represents the sound-board.
C is the back frame board.

page_text: F is the usual iron frame which is firmly secured to 'the 'back-frame-board by a
number of screws or bolts at the margin of the frame. In addition to such bolts 1
provide also a series of bolts F1 extending through the hitchpin strip of the iron
frame into a supporting plank F?. This series of bolts imparts great stiffness and
strength to the frame of the piano.
The partitions Bibetween the sound-board and the back-board afford a number
of flues or pipes under the strings and the proper relative dimensions of such pipes
are secured by spacing the partitions at proper distances from each other and for
the treble-strings of the piano there can be employed further plank pieces or
plates C¹ and C placed on the back-frame board to reduce the dimensions of the
Hue to the proper degree. The construction and relative arrangement of the tubes
and strings are clearly illustrated in the several figures of the drawings. Each
tube has an opening b at the end next the wrest-plank and corresponding openings 61
are made in the iron frame to register with the openings b.
It will be observed that toward the bass part of the piano and in the over string
bass the space being limited it becomes necessary for each of the several tubes
which I have designated by the reference-figure B₁ to answer for several tones. The
air spaces of the tubes may be calculated to the simplest relative sound such as
octaves, fifths, and fourths adding the thirds where the space will admit of it
leaving the remaining tones to vibrate in sympathy with them.
The tubes
respond by sympathetic vibration, and are scaled similar to organ pipes to proper
lengths and breadths. For the treble and middle strings of the piano I employ
a tube for each set of strings or tone arranged according to the chromatic scale
except that for the last octave I may omit the partitions altogether.
It is not absolutely necessary for the tubes to be immediately under the set of
strings to which they respond as I find they will respond if some distance away but
it is desirable to have them placed as near to the strings they belong as the scale of
the piano will admit. My invention may be applied either to upright or grand
pianos and its advantage in securing fulness of tone will be appreciated by the
skilled musician. In pianos of the construction heretofore employed there has
always been difficulty experienced in that the sound-board in time loses its elasticity
thereby injuriously affecting the tone of the piano. In my improved construction
where the air tubes take the place of the sound-board this cannot happen. I am
also enabled by the use of the partitions to obtain a strong support for the bridges
and thereby to prevent the evil consequences resulting from sinking of bridge away
from the strings.
My invention is susceptible of modification in form, proportions, and details of
construction by those skilled in the art.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
:―
1. In a piano-forte the combination with the sound-board and strings of pipes or
flues in contact with the sound-board and arranged in position to receive the vibra-
tions of the strings and corresponding thereto in pitch said strings being arranged
outside the pipes or flues substantially as and for the purpose described.
2. In a piano-forte the combination with the sound-board and strings of pipes
underlying and in contact with the sound-board and corresponding in pitch to the
strings substantially as and for the purposes described.
3. In a piano-forte the combination with the sound-board and strings of pipes
underlying and in contact with the sound-board and corresponding in pitch to the
strings said pipes being open at one end and closed at the other substantially as and
for purposes described.
4. The combination of the sound-board and back frame interposed partitions
connecting them and forming pipes underlying the sound-board an elevated bridge
situate on the outside of the sound-board and supported by the partition and strings

page_text: which pass over the bridge on the outside of said pipes substantially as and for the
purposes described.
Dated this 26th day of April 1892.
FREDERIC PRINCE,
1, Quality Court, Chancery Lane, London, W.C.,
Agent for Applicant.