AN IMPROVEMENT IN THE FRAMES OF PIANOFORTES
Year: 1855

page_text: LETTERS PATENT to John Dewrance, of Barge Yard, Bucklersbury, in
the City of London, Engineer, for the Invention of "AN IMPROVEMENT IN
THE FRAMES OF PIANOFORTES."
Sealed the 11th. March 1856, and dated the 13th October 1855.
PROVISIONAL SPECIFICATION left by the said John Dewrance at the
Office of the Commissioners of Patents, with his Petition, on the 13th
October 1855.
I, JOHN DEWRANCE, of Barge Yard, Bucklersbury, in the City of London,.
Engineer, do hereby declare the nature of the said Invention for "AN
IMPROVEMENT IN THE FRAMES OF PIANOFORTES" to be as follows:-
In place of making the framing of pianofortes of wood, as is usually the
case, I propose to construct this part of the instrument of cast iron, of any
convenient or suitable section and shape, according to the description of
instrument to which the improved framing is to be applied.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed'
by the said John Dewrance in the Great Seal Patent Office on the
12th April 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, J, JOHN
DEWRANCE, of Barge Yard, Bucklersbury, in the City of London, Engineer,
send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of October, in the year of our Lord
One thousand eight hundred and fifty-five, in the nineteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Dewrance, Her special license that I, the said John
Dewrance, my executors, administrators, and assigns, or such others as I,
the said John Dewrance, my executors, administrators, and assigns, should
at any time agree with, and no others, from time to time and at all times
thereafter 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 "AN IM-
PROVEMENT IN THE FRAMES OF PIANOFORTES," upon the condition (amongst
others) that I, the said John Dewrance, by an instrument in writing under
my hand and seal, sliould particularly describe and ascertain the 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 Öffice within six calendar months
next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Dewrance, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the Drawing hereunto annexed, and to the
letters and figures marked thereon (that is to say) :-
Hitherto the framing of pianofortes, or that part of the instrument which
receives the strain of the strings, has been made principally or wholly of wood,
and to enable it to resist the strain, which is very considerable, it has been
found necessary to make the framing very strong, and consequently heavy and
bulky. Sometimes, in order to increase the rigidity of the framing and give
increased strength, manufacturers of pianos have added transverse and longi-
tudinal metal bars, and also metal plates, to this part of the instrument; these
contrivances, however, add considerably to the weight of the instrument, and
materially increase the cost of manufacture.
My Invention has for its object to give increased rigidity to the framing,
thereby reducing the liability of the instrument to get out of tune, and con-
siderably increasing the power and brilliancy of the tone, and at the same time
materially reducing the cost of manufacture. These and other advantages may
be obtained by the use of my improvements, which consist in a novel mode of
constructing the framing (of these instruments) of cast iron. The shape of the
framing must of course depend upon the particular description of instrument to
which it is to be applied, and the particular section of the iron framing must.

page_text: also in a great measure depend upon the same circumstances, and may be
varied at the discretion of the manufacturer; but I may mention that in
practice I have found the T-shape bar to answer the purpose, and therefore I
prefer to use this form, although I do not mean to confine myself thereto.
For the purpose of receiving the pins on which the strings are secured, I
employ a piece of hard wood, which must be let into and secured by means of
bolts, screws, or suitable contrivances in a recess made for that purpose in the
metal frame. The surface of this piece of wood may, if thought desirable, be
covered with a plate of soft metal, such as zinc or tin, so as to enable the bolts
to hold the wood more securely. The sounding board and bridge I propose;
as heretofore, to make of wood, and secure the same to the cast metal frame, in
which must be made a suitable recess to receive the same.
In order, however, that niy Invention may be clearly understood, I have in
the accompanying Drawing shewn various Figures of cast-iron framings of.
different shapes which I propose to use for pianofortes of different kinds
of construction.
Fig. 1 is a front view of one of my improved cast-iron frames; Fig. 2, a
back view; and Fig. 3 is a vertical section of the same, taken in the line A, B,
of Fig. 1. This frame is intended for an upright, cottage, or cabinet pianoforte;
and is constructed with a series of bars a, a, a, carried from top to bottom of
the frame, the bars being of various strengths to compensate for the unequal
strain of the various strings on the head beam. I find it convenient to make
the central vertical bar a of greater strength, and the vertical rib or feather
thereof of greater depth, than in the others; and by that means I divide the
framing, as it were, into two parts, the bass part being thus separated from
the treble, and the central bar a being of such strength as to prevent the
strain of the bass strings from affecting the treble.
It will be seen, on referring to Fig. 1, that there is a transverse flange or
rib 6 carried from side to side of the frame, and is intended to form a recess
and support to receive the piece of hard wood in which the pegs or pins of the
strings are inserted.
Fig. 4 is a front view of another form of cast-iron framing, in which the
longitudinal bars a, a, are dispensed with, the compensation or resistance to
the strain of the strings being effected by a different mode of constructing the
head beam, as shewn at I, I, I; Fig. 5 is a back view of the same frame; and
Fig. 6 is a sectional view thereof, taken in the line C, D, of Fig. 5.
It will be seen, on referring to Fig. 6, that the ribs I, I, I, on the back side of
the head frame, are of considerable depth and strength, and calculated to resist
all tendency in the frame to torsion. A flange b, in this instance, is also

page_text: employed to support the piece of wood which receives the pins or pegs of
the strings.
Fig. 7 is a front view of one of my improved cast-iron, framings intended.
for a grand piano; Fig. 8 is a back view of the same; and Fig. 9 is a
sectional view, taken in the line E, F, of Fig. 7. In this instance the strain
of the strings is counteracted both in the head beam I and by the central
longitudinal bar J.
Fig. 10 is a front, view of another cast-iron framing, which is somewhat
similar in construction and arrangement to that shewn at Figs. 8 and 9, the
only difference being that some modification is made in the construction of.
the head. beam, whereby the. varying strain. of the strings, is counteracted
or resisted.
I would observe that the several parts of these metal frames are all cast
together and form one piece, and although I have spoken of cast iron, as the
material to be employed. in making the metal, frame, yet I have found that.
other metals or alloys of metals may be used with advantage for the best class
of instruments; I therefore wish it to be understood that I do not mean to
confine myself to the use of cast iron as the metal to be employed for the.
above purpose.
Having now described my Invention of an improvement in the frames of.
pianofortes, I would observe, in conclusion, that what I consider to be new,
and therefore wish to claim as the Invention secured to me by Letters Patent
as aforesaid, is, constructing the framing of pianofortes of cast metal, as above
shewn and described.
In witness whereof, I, the said John Dewrance, have hereunto, set my:
hand and seal, the Twelfth day of April, in the year of our Lord One
thousand eight hundred and fifty-six.
Witness,
J. W. MOFFATT,
66, Chancery Lane.
JOHN DEWRANCE. (L.S.)