IMPROVEMENTS IN THE CONSTRUCTION OF PIANOFORTES
Year: 1870

page_text: LETTERS PATENT to Henry John Kirkman, of No. 3, Soho Square,
in the County of Middlesex, Pianoforte Manufacturer, for the
Invention of 66 TUDDARDIMA
PROVISIONAL SPECIFICATION left by the said Henry John Kirkman
at the Office of the Commissioners of Patents, with his Petition,
on the 8th April 1870.
I, HENRY JOHN KIRKMAN, of No. 3, Soho Square, in the County of
Middlesex, Pianoforte Manufacturer, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF PIANOFORTES,"
to be as follows:-
My Invention relates to the employment of steel bracings or tension
bars for resisting the pull of the strings and supporting the wrest plank.
The wrest plank may be formed wholly of steel or partially of steel and
partially of wood, and the stud bridges or bridges on the wrest plank will
be applied wholly in the steel or partly in the steel and partly in the
wood, depending upon the character of the tone desired to be obtained

page_text: In the formation of the wrest plank the steel and the wood parts are
tongued together, or otherwise secured, and the steel portion may be
continuous from end to end, or otherwise. The number of these steel
bracings or tension bars, as well as the form and position of them and
the form and position of the wrest plank will vary.
The steel I prefer to be wrought, and the bracings or tension bars
are connected, by preference, direct to the metal part so far as it goes
of the wrest plank, as well as to the metal string plate.
I also in some cases apply the tension or bracing bars in a line with
the strings, so that the direction of strain on such bars may be through
the centre thereof, or nearly so. To admit of such arrangement of the
bars the bridges are recessed at those parts.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry John Kirkman in the Great Seal Patent
Office on the 8th October 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
JOHN KIRKMAN, of No. 3, Soho Square, in the County of Middlesex,
Pianoforte Manufacturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day of April, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Henry John Kirkman, Her special licence
that I, the said Henry John Kirkman, my executors, administrators,
and assigns, or such others as I, the said Henry John Kirkman, my
executors, administrators, and assigns, should at any time agree with, and
no others, from time to time and at all times thercafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
THE CONSTRUCTION OF PIANOFORTES," upon the condition (amongst others)
that I, the said Henry John Kirkman, my executors or adminis-
trators, by an instrument in writing under my, or their, or
their hands and seals, should particularly describe and ascertain the
one of

page_text: nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said Henry John Kirkman, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say :-
My Invention relates to the employment of steel bracings or tension
bars for resisting the pull of the strings and supporting the wrest plank.
The wrest plank may be formed wholly of steel or partially of steel and
partially of wood, and the stud bridges or bridges on the wrest plank
will be applied wholly in the steel, or partly in the steel and partly in
the wood, depending upon the character of the tone desired to be
obtained. In the formation of the wrest plank the steel and the wood
parts are tongued together or otherwise secured, and the steel portion
may be continuous from end to end, or otherwise. The number of these
steel bracings or tension bars, as well as the form and position of them
and the form and position of the wrest plank will vary.
The steel I prefer to be wrought, and the bracings or tension bars are
connected, by preference, direct to the metal part so far as it goes of the
wrest plank, as well as to the metal string plate.
I also in some cases apply the tension or bracing bars in a line with
the strings, so that the direction of strain on such bars may be through
the centre thereof, or nearly so. To admit of such arrangement of bars
the bridges are recessed at those parts.
But that the Invention may be fully understood, I will by the aid of
the accompanying Drawings proceed to describe means pursued by me
in carrying the same into effect.
DESCRIPTION OF THE DRAWINGS.
Figure 1 shows a plan view of a portion of a horizontal pianoforte
with parts thereof arranged according to my improvements; Figure 2 is
a longitudinal section thereof showing one of the bracing and tension
bars; Figures 3, 4, and 5 shew other similar longitudinal sections of
parts showing other or portions of other of the bracing or tension bars;
Figures 6, 7, 8, 9, 10, and 11, also show some of the parts more in

page_text: In cach of these views the same letters are employed to indicate
corresponding parts wherever they occur.
a, a, represents a portion of the outer case of the iustrument; b is
the metal string plate; and c, c³, the wrest plank, the front portion c
thereof being formed by a bar of steel which extends from one side to
the other of the instrument along the whole front of the wooden
portion c¹ of the wrest plank, and it is by preference of the same thick-
ness as that wooden portion. I prefer also that this steel portion c of
the wrest plank be formed with a groove c³ in its inner edge to receive
a corresponding tongue from the portion c', by which the parts c, c', may
be more firmly connected together. The red dotted line a represents
the line of the stud bridges, and according to the arrangement of the
parts c, c¹, shown by these Figures now under description, these stud
bridges will be inserted partly in the steel portion c of the wrest plank
and partly in the wooden portion c¹ theroof, but this may be varied, as
hereafter referred to.
One of the stud bridges is represented full size by the three Figures
9, 10, and 11, and it will be seen on reference to those Figures that
each stud bridge is formed as heretofore with a screw stem to screw
into corresponding holes prepared for them in the steel or other portion
of the wrest plank, as the case may be.
the respective bracing or tension bars.
d, e, f, g, h, and i represent
The form of the front ends
of the steel bracing or tension bars and the method of connecting them
to the portion c of the wrest plank being clearly shown by the Drawings, I
have not thought it necessary further to describe them.
Figure 12 shows by a plan view a modification of the parts of the
wrest plank in which the steel portion c thereof has a form given to it
corresponding with the line of the stud bridges, so that all the stud
bridges may be fixed in the metal portion of the wrest plank. The line
of direction of the stud bridges is also shown in this Figure by red
dotted line x. Figures 13 and 14 show the steel portion c of the wrest
plank according to this modification separately.
The form of the bar c may be otherwise varied, and in some cases it
may extend towards the front of the instrument so as to render a wooden
plank c unnecessary.
In some cases, particularly in upright pianofortes, I apply the tension
or bracing bars in a line with the strings.

page_text: Figures 15 and 16 show by front views on a larger scale portions of
two bracing or tension rods j and thus arranged; Figure 17 is a
section of the parts with a side view of the bar j, shown by Figure 15.
In these illustrations, as in the former, c represents the steel portion of
the wrest plank, and e' the wood portion thereof.
Figure 18 shows by horizontal view a portion of the middle bridge
recessed at w to admit a barj or to pass without touching it.
Thus it will be seen that in carrying out my improvements the metal
string plate, the tension or bracing bars, and the wrest plank when
fitted and secured together, form a complete metallic frame to resist
the strain upon the instrument.
Having thus described my Invention and means which I adopt in
carrying the same into effect, I would have it understood that although
I have only shown my improvements applied to a horizontal grand and
to an upright pianoforte, they are equally applicable to other varieties
of pianofortes; and what I claim as my improvements in pianofortes
is,—
First. The employment of steel in the formation of the tension or
bracing bars.
Secondly. I claim the forming the wrest plank wholly or partially of
steel substantially as described.
Thirdly. I claim the application of stud bridges in the steel bar c
substantially as described.
Fourthly. I claim the formation of a solid metal frame by the con-
nection of the string plate tension or bracing bars and steel bar forming
the wrest plank or a part thereof, substantially as described.
In witness wheroof, I, the said Henry John Kirkman, have here-
unto set my hand and seal, this Seventh day of October, in the
year of our Lord One thousand eight hundred and seventy.