IMPROVEMENTS IN PIANOFORTES
Year: 1880

page_text: LETTERS PATENT to Henry William Pohlmann, of the Firm of Pohlmann and
Sons, of Halifax, in the County of York, Pianoforte Manufacturers, for an
PROVISIONAL SPECIFICATION left by the said Henry William Pohlmann
at the Office of the Commissioners of Patents on the 30th July 1880.
HENRY WILLIAM POHLMANN, of the Firm of Pohlmann and Sons, of Halifax, in
the County of York, Pianoforte Manufacturers. "IMPROVEMENTS IN PIANOFORTES."
This Invention relates to the inward parts of pianofortes, and the object of the
several improvements is to obtain lightness combined with strength, improvement,
and continuity of the tone.
The Invention relates, firstly, to the wrest plank, whether applied to horizontal
or upright pianofortes, and the improvements consist in forming a double metal
bearing thereon in combination with the " 'capodastro" or downward bearing. If
the wrest plank be metal and cast to the metal bridge, the double bearings are cast
or formed thereon, but if the wrest plank be formed of wood, a metal piece having
two bearings may be attached thereto, also in combination with the "capodastro
or downward bearing.
Secondly. The Invention relates to the metal frames of horizontal pianos.
Hitherto this class of pianos have had two separate and distinct frames, one
composed of metal and the other of wood.
My improvements consist in dispensing with the wood frame and in forming the
two frames into one by casting them together in one piece, forming a hollow metal
frame, into which the sound board is placed or suspended; or the top and bottom
parts of the metal frames may be cast separate and bolted together, forming a
hollow casting for the introduction of the sound board.
Thirdly. The Invention relates to the double metal frame or hollow casting used
in horizontal and upright pianos, and the improvements consist in extending the
framework upwards at each side, into which space the wrest plank is inserted,
resting upon and being supported by a solid metal surface, by which means the

page_text: wrest plank cannot be pulled forward by any extra tension of the wires, or be
removed from its position sideway.
Fourthly. The Invention relates to the construction of the metal frame, and the
improvements therein consist in making the frame and connecting bars angular or
hollow, by which means the frame is much lighter and a considerable saving of
metal is effected.
Fifthly. The Invention relates to the fixing of the sound board, and the improve-
ments consist in fixing the sound board within the hollow metal frame previously
mentioned to the edges all around and making the edges immovable. This method
of fastening allows the sound board to be more arched or convex than has hitherto
been practicable, thus increasing the volume of tone and sustaining power.
Sixthly. To the making of a double vibrating reflector or sound board constructed
on the principle of a violin, and is equally applicable to borizontal or upright
pianofortes where the above mentioned metal frame is employed.
The two sides of the vibrating reflector are connected beneath the sound board
bridge by sound posts or by a duplicate bridge. The inner space of the vibrating
reflector to be either in one compartment or divided into three.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry William Pohlmann in the Great Seal Patent Office on the
29th January 1881.
HENRY WILLIAM POHLMANN, of the Firm of Pohlmann and Son, of Halifax, in
the County of York, Pianoforte Manufacturers. "IMPROVEMENTS IN PIANOFORTES."
"
This Invention relates to the inward parts of pianofortes, and the object of the
several improvements is to obtain lightness combined with strength, improvement
in quality, and continuity of the tone.
The Invention relates,―
Firstly. To the wrest plank, whether applied to horizontal or upright pianofortes,
and the improvemenis consist in forming a double metal bearing thereon in combi-
nation with the " capo d'astro" or pressure, bar, or downward bearing. If the
wrast-plank be metal the double bearings are cast or formed thereon, but if the
wrest plank be formed of wood, a metal piece having two bearings may be attached
thereto, also in combination with the "capo d'astro or pressure bar.
>>
This part of my Invention is illustrated in Fig. 1, where A is the double bearing
bridge, and B the pressure bar; by means of this divided bearing bridge the tension
of the strings is made more equal and the strings keep longer in tune, at the same
time the pull-over strain on the wrest plank is lessened. In horizontal pianos this
double bearing is specially useful, as the double bearing or metal bridge running
through the scale from treble to bass and cast with the frames allows the scale to
be adjusted or formed with greater mathematical accuracy than can be obtained
by studs or separate bearings for individual strings, whilst the saving in cost and
labour will be evident to practical persons engaged in the manufacture of horizontal
frame pianofortes.
Secondly. The Invention relates to the metal frames of horizontal pianos.
Hitherto this class of pianos have had two separate and distinct frames, one
composed of metal and the other of wood. My improvements consist in dispensing
with the wood under frame, and in forming the two frames into one by casting
them together in one piece, thus forming a hollow metal frame into which the
sound board, either double or single, is placed or suspended.
This part of my Invention is illustrated more particularly in Fig. 2, which is a
cross section of treble end of a horizontal grand piano, where C is the double frame
made in one casting; or the top and bottom parts may be cast separate and
fastened together, forming a hollow casting for the introduction of the sound board.
Fig. 1 is a front view, and Fig. 6 (Sheet 2) is a view of the underside.
Thirdly. The Invention relates to the double metal frame or hollow casting used in
upright pianos, and the improvements consist in extending the framework upwards
at each side, or back and front, into which space the wrest plank is inserted, resting
upon and being supported by a solid metal surface.
This part of my Invention is illustrated in Fig. 3, where D is the double metal
frame, the front and back part E and F being extended for the introduction of the
wrest plank G, by which means the wrest plank cannot be pulled forward by any
extra tension of the wires, or be removed from its position sideway.
Fourthly. The Invention relates to the construction of the metal piano frames,
and the improvements therein consist in making the frames and connecting bars
corrugated or hollow, as shewn at H, in Figs. 1 and 6, and in details, Figs. 4 and 5,
by which means the frames are much lighter, and a considerable saving of metal is
effected, at the same time the strength is increased.
Fifthly. To the making of a double vibrating reflector or soundboard applicable
either to horizontal or upright pianos, consisting of the upper soundboard and a
vibrating reflector underneath, or at the back in upright pianos acting as a second

page_text: sound-board to reflect and increase the tone, the two parts being concave and
fastened completely around the outer edges in whatever shape the sound board
may be used, and connected in the middle part under the bridge by wooden dowels
or sound posts somewhat on the principal of a violin. The double sound board may
be applied either to wood or iron frame pianos. In wood frame pianos it is fixed
entirely at the back, being fixed together all around the outer edges and connected
with the front soundboard under the belly bridge by dowels or sound posts, so as
to cause both the front soundboard and the back vibrating reflector to retain the
concave form when the pressure of the strings is put on the bridge.
This part of my Invention is also illustrated in Fig. 2, J being the soundboard,
and K the vibrating reflector connected together by dowels L, the part M is the
belly bar, and N the vibrating reflector bar. The air space is greater at the bass
end than at the treble end, so that whilst retaining the concave form the sound
boards and the air space diminish towards the treble. P are openings to allow the
sound to escape.
Having now described my Invention, and the manner in which the same is
to be performed, I would have it understood that I do not confine myself to
the exact details herein shewn and described, as some of the parts may be varied
without departing from their essential feature; but what I consider to be new and
therefore claim as my Invention is,―
Firstly. The combination and arrangement of the metal double bearing bridge A
and pressure bar B, substantially as shewn and described.
Secondly. The double metal frame when used for horizontal pianos, substantially
as described and shewn in Fig. 2.
Thirdly. The extension of the back and front parts of the metal frame for
supporting the wrest plank in upright pianos, substantially as described.
Fourthly. The corrugated or hollow cast metal frame, substantially as shewn
and described.
Fifthly. The double vibrating reflector composed of the two concave parts J and
K, for the purpose substantially as shewn and described.
In witness whereof, I, the said Henry William Pohlmann, have hereunto set
my hand and seal, this Twenty seventh day of January, in the year of our
Lord One thousand eight hundred and eighty-one.
HENRY W. POHLMANN. (L.S.)