IMPROVE- MENT IN PIANOFORTES, CONSISTING IN THE NEW CONSTRUCTION ON THE PRINCIPLE OF ACOUSTICS OF A SOUNDING BODY APPLICABLE TO EVERY DESCRIPTION OF PIANOFORTES
Year: 1835

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, 1, ROBERT
WOLF, of Cornhill, in the City of London, Musical Instrument Maker, send
greeting.
WHEREAS His most Excellent Majesty King William the Fourth, by
His Letters Patent, bearing date the Sixth day of November, in the fifth
year of His reign, did, for Himself, His heirs and successors, give and
grant unto me, the said Robert Wolf, His especial licence that I, the said
Robert Wolf, my exors, adññors, and assigns, or such others as I, the said
Robert Wolf, my exors, admors, and assigns, should at any time agree with,
and no others, from time to time and at all times during the term of years
therein expressed, should and lawfully might make, use, exercise, and vend,
within England and Wales and the Town of Berwick-upon-Tweed, an Inven-
tion communicated to me by two Foreigners residing abroad, for an "IMPROVE-
MENT IN PIANOFORTES, CONSISTING IN THE NEW CONSTRUCTION ON THE PRINCIPLE OF
ACOUSTICS OF A SOUNDING BODY APPLICABLE TO EVERY DESCRIPTION OF PIANOFORTES;"
in which said Letters Patent there is contained a proviso obliging me, the said
Robert Wolf, by an instrument in writing under my hand and seal, particularly to
describe and ascertain the nature of my said Invention, and in what manner the
same is to be performed, and to cause the same to be inrolled in His Majesty's
High Court of Chancery within six calendar months next and immediately after
the date of the said recited Letters Patent, as in and by the same, reference
being thereunto had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, 1, the said
Robert Wolf, do hereby declare that the nature of my said Invention, and the
manner in which the same is to be performed, is described and ascertained as
follows, that is to say:-
in
My Invention consists in the substituting a hollow receptacle or shell of a
curvilinear shape, which I call a sounding body, in lieu of the usual sounding
board in pianofortes. The precise shape of the sounding body is not material,
provided the sides be curvilinear, or limited by curved lines, and may be made
any of the shapes shewn by the Drawings annexed, but I consider the
shapes shewn by Figures VII., and IX. better than the funnel shape, the
hemisphere, or the elipse or longitudinal section of an egg, shewn in the
Drawings Figures I., III., V., and their respective sections or profiles
II., IV., VI. The upper part of these several sounding bodies I call the
sounding board, in which a sounding hole must be made, but in the forms
shown by Figures VII. and IX., at least three sounding holes had
better be made, as shown by the oval black line, and also the oval dotted
lines in those Figures, but the sounding holes shewn by the dotted lines may
be made either in the sounding board or in the bottom of the sounding body.
The bodies or shelves in the cone or funnel shape, and also in the hemispherical
shape, and in the elliptic or longitudinal section of an egg shape, are to be
made of veneers of maple wood, sycamore wood, or hare wood, or any other
wood of a similar nature, such as is generally used for the bodies of guitars,
violins, or other similar musical instruments, which veneers should not exceed in
thickness one tenth of an inch, and should be cut into triangular pieces for the
cone shape, and into ribs or gores for the other two shapes, similar to the
pieces of silk or other substance forming an air balloon, and as shewn by the
dotted lines in Figures II., IV., and VI., so as when put together they will
form the shape required, and the edges to be carefully glued together upon a
block or mould of wood, of the required size and shape, after which they are
to be neatly cleaned off and made smooth. The sounding bodies in the forms
shewn by Figures VII. and IX. are to be constructed as follows, that is to
I make a strong mould or frame of wood on the plan of the mould used
by guitar makers, but in the shape of the sides of the sounding body to be made,
in which the sides of the sounding body are to be framed or curved by bending,
these sides being first cut as nearly as can be to the required shape, and after-
wards planed down in the mould to the precise shape. When found necessary
the bending may be assisted by the application of steam or warm water, after the
well known manner in use among the makers of guitars and violins, the sides
to be made of veneers of maple, sycamore, or hare wood, or other similar
say,

page_text: wood, as before mentioned, of a thickness not exceeding one tenth of an inch,
and of as few picces as possible. A small strip of wood, similar to the lining
used in violins, is then to be glued round the inside of the sides of the sound-
ing body, level with their upper surface, and also a similar strip of wood round
the inside of the sides, level with their lower surface, not only to strengthen
the sides and hold them in form, but also to hold more firmly the bottom and
also the top or sounding board to be glued thereon. The bottom is to be mado
of the same wood as the sides, but of about the sixth of an inch thick, and the
bottom and also the top or sounding board are then to be glued to the sides,
while they remain in the shape or mould, which will cause the bottom to curve
to the required form, the sounding board remaining flat, and the bottom may
be also before the top or sounding board is glued on, strengthened in that
shape by means of ribs of soft wood cut to the curve required, and glued across
the inner surface of the bottom, at intervals, as shewn by the dotted lines
across Figures VII. and IX., similar to the ribs of a common sounding
board for pianofortes. The sounding board, which is to be of the usual
thickness of sounding boards for pianofortes, is to be made of soft wood
with a straight grain (Swiss belly wood, of which the sounding boards of piano-
fortes are usually made, being preferred) and the grain of the wood should
run parallel to the direction of the strings, which are indicated by red lines
in the Drawings annexed, and is also to be strengthened by ribs of soft wood
in the manner sounding boards of pianofortes are usually strengthened. The
body being thus constructed I attach the same to the pianoforte by either of
the two following methods. By the first method I glue to the inside of the
sides of the sounding body a number of small blocks of wood sufficiently
large to receive and hold the worm of an iron screw or screws, about an inch
long. I consider about ten or eleven of these blocks sufficient for the
sounding body, but of course the number will increase or decrease with the
increased or diminished length of the body, the object being to hold the
sounding body quite firm when the instrument is strung, and in the circular
sounding body they may be equally disposed, but in the elliptical sounding body
they are to be placed closer together at the smaller end of the body than at the
larger end, and in the places shewn in the Drawing, Figure VII., I consider
the best places for the purpose. I then screw with one or two screws about
an inch long, strong iron cramps bent in a right angle, as shewn at the
smaller end of Figure VIII. to those parts of the outside of the sides of the
sounding body where the small blocks of wood are glued on the inside, and
by means of another screw I fasten the iron cramp to the bracings or interior
of the case, which must be constructed so as to surround the sounding body on

page_text: block.
all its sides. My method of constructing the bracings, and instead of the
usual mode, is to put a strong oak board, of at least an inch and half thick,
filling the whole of the case passing over the face of the rest plank or block.
and thereby supplying the place of the usual wainscot for receiving the pins.
This board I by preference compose of two layers glued together, crossing the
grain of the wood, and I attach it with glue firmly to the frame and rest
In this board the shape of the shell or sounding body is cut out, but
rather larger than the sounding body, and so as freely to admit the same,
without at all touching, so that the sounding body is left perfectly free from
the case bracings or board, except where it is attached by the iron cramps,
and this board is further strengthened by bracings behind in the usual manner,
where they do not interfere with the sounding body. The second method of
attaching the sounding body to the instrument is to make the sounding board
all round about an inch larger than the sounding body to which it is attached,
so that it projects about an inch over the sides of the sounding body in each
direction, as shewn at the larger end of the Drawing, Figure VIII. I then
glue about about one half of this projecting edge or flange of the sounding
board in a rabbet round the opening, made to receive the body or shell in the
bracings or interior of the case, made as before mentioned, so as to allow a
space between the bracings and the sounding body, sufficient to leave the
latter free on all its sides, which rabbet is to be sufficiently deep to give the
strings a proper bearing, and in this flange, between the bracings and the
sounding body, small holes may be bored, in order to prevent as much as
possible the vibrations being carried over from the sounding body to the
case, care being taken not to bore the holes so as to weaken the wood too
much, and the only rule for which is the discretion of the workman, as the
pianoforte may be used without such holes. The bridge is placed on the
sounding board in the usual manner, but the bridge may also be made in
the shape shewn in the Drawings, Figure III. and Figure V., in which
case the largest or bass string must be placed in the centre or largest diameter
of the sounding board, and the other strings alternately on each side of
the first, as they decrease in length. In this mode of making the bridge a
cross action would be necessary, but I do not claim such mode of making
the bridge as any part of my Invention, which is confined to the curvilinear
sounding bodies, as already mentioned, and which are illustrated by the several
Drawings hereto annexed, and to which, as part of this description, I refer.
The size of the several sounding boards, Figure I., Figure III., and Figure V.,
and consequently of the sounding bodies to which they are attached or form a
part, will be determined by the openness of the scale, or distance between

page_text: string and string, and consequent length of the bridge. I consider in a
circular sounding board a diameter of from two feet six inches to three fect,
the best, and when the sounding body is hemispherical, the depth will be one
half of the diameter, and when the sounding board is an ellipse, as in Figure
V., the length to be in proportion, so as to produce the ellipse, and the depth
of the body to be in the deepest part one half the cross diameter of the sound-
ing board. The sounding boards, Figures VII. and Figure IX. are drawn to
a reduced scale of one tenth the size, or one tenth of a foot to a foot, as shewn
in the annexed Drawing, and Figure VIII. is a profile of the sounding body,
of which Figure VII. is the surface or sounding board. Figure VII. is
intended for a square horizontal pianoforte, and Figure IX. is intended for
an upright or for a horizontal grand pianoforte. It is necessary that these
sounding bodies should regularly decrease in depth as well as in width from
the part where the larger or bass strings pass over to the part where the
shorter or treble strings pass over, the decrease in depth always taking
place in lines parallel with the strings, the depth being equal on both sides
the shell or sounding body at the same string, and thus decrease in depth
and width, as shewn in Figure IX. and Figure X. The seven red lines
indicating the parts where the seven strings, each producing the note F, pass,
and shewing the depth and width of the sounding body, according to the
scale which is marked on the plan, and which is a scale of one tenth the
actual size, or one tenth to a foot; the depth in Figure IX. at each red line
is marked by the depth of the arrow attached to it. Figure X. gives the
depth alone. The scale of widths and depths has been determined by experi-
ment, the object being to make the vibrations of the sounding body correspond
respectively with the vibration of the respective strings. This scale need not
vary with the quality of the wood used in forming the sounding body, because
a variation may be made in the thickness of the wood, after the manner now
When the bridge is short,"
practised in making common sounding boards.
and by consequence rapidly curved, the width cannot in every part be made
correctly according to the scale, but the scale should not be departed from
more than is rendered absolutely necessary by the difficulties of construction.
In witness whereof, I, the said Robert Wolf, have hereunto set my
hand and seal, this Fifth day of May, in the year of our Lord One
thousand eight hundred and thirty-five.

page_text: AND BE IT REMEMBERED, that on the Fifth day of May, in the year
of our Lord 1835, the aforesaid Robert Wolf came before our said Lord
the King in His Chancery, and acknowledged the Specification aforesaid,
and all and every thing therein contained and specified, in form above
written. And also the Specification aforesaid was stamped according to the
tenor of the Statute made for that purpose.