IMPROVEMENTS IN THE CONSTRUCTION OF PIANOFORTES
Year: 1862

page_text: LETTERS PATENT to Henry Fowler Broadwood, of Great Pulteney Street,
in the County of Middlesex, Pianoforte Maker, for the Invention of
"IMPROVEMENTS IN THE CONSTRUCTION OF PIANOFORTES."
PROVISIONAL SPECIFICATION left by the said Henry Fowler Broadwood
at the Office of the Commissioners of Patents, with his Petition, on the
30th April 1862.
J, HENRY FOWLER BROADWOOD, of Great Pulteney Street, in the County of
Middlesex, Pianoforte Maker, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF PIANOFORTES," to be as
follows:-
My Invention applies to that part of a pianoforte technically termed the
"wrest plank," into which are fitted the "wrest pins" used for drawing up
or tuning the strings, the object being to facilitate the tuning of pianofortes,
and to maintain the tension of the strings. To this end I cover the part of
the wrest plank where the wrest pins enter with a metallic plate which I term
the "pin plate," and I use wrest pins formed with a thread upon them after
the manner of a screw. Of these wrest pins I use three varieties, namely,
either 1, pins with a long thread for screwing both into the metallic pin plate,
and into the wood beneath it; 2, pins with a shorter thread upon the upper
portion for screwing into the pin plate only; or 3, pins with a thread upon the
lower portion for screwing into the wood only.
In applying my Invention to grand pianofortes, I connect the metallic pin
plate with a certain bar of the metallic framing attached to the wrest plank, and
called the sweep bar, by forming them out of one piece of metal bent into the

page_text: shape of the letter L. This Invention, besides increasing the facility of tuning
the instrument, and the power of its standing in tune, will add much to the
strength and durability of the instrument.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Fowler Broadwood in the Great Seal Patent Office
on the 24th October 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
FOWLER BROADWOOD, of Great Pulteney Street, in the County of Middlesex,
Pianoforte Maker, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirtieth day of April, in the year of our Lord One
thousand eight hundred and sixty-two, in the twenty-fifth year of Her reign,
did, for Herself, IIer heirs and successors, give and grant unto me, the said
Henry Fowler Broadwood, Her special license that I, the said Henry Fowler
Broadwood, my executors, administrators, and assigns, or such others as I, the
said Henry Fowler Broadwood, 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 nake, 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 Fowler Broadwood, by an instru-
ment in writing under my hand and seal, should 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 Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said Henry Fowler Broadwood, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, 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):-
My Invention applies to that part of a pianoforte technically termed the
"wrest plank," and to the pins fitted into the same called "wrest pins," and
used for drawing up or tuning the strings. The object of the said Invention
is to obtain a mode of construction, which while it affords greater facility in
0

page_text: tuning, shall add to the general strength, stability, and durability of this part
of the instrument, and improve the power of standing in tune.
The Figures marked Numbers 1 to 6 in the accompanying Sheet of
Drawings, will illustrate the nature of my Invention, and for the sake of
clearness I have omitted all parts which are not relevant thereto.
Referring to Figures 1 and 2, A is the "wrest plank "constructed of various
thicknesses of wood in the ordinary way, but which I find I can by using
my improvement make thinner than usual. I cover the upper surface of
this plank with a plate of metal B, which may be made either of cast iron,
wrought iron, gun metal, or brass, according to circumstances, and which
is fastened to the wood of the plank by ordinary wood screws in sufficient
number to hold it firmly down; this plate I term the "pin plate." C, C, are
the wrest pins, round which the strings are lapped, and these I construct in
either of two ways, which are shewn in Figures 1 and 2 respectively. They
are formed in each case with a thread cut upon them after the manner of a
screw, but the length of this thread differs in the two varieties.
In Fig. 1 the thread is long, and it screws both into the metallic piu
plate B, which is properly tapped to receive it, and into the wood A of the
plank below.
In Fig. 2 the thread is shorter, and screws only into the pin plate, the
part which enters into the wood below not being screwed, but only slightly
roughed to give friction in the wood in the usual way. Several advantages
arise from this plan of construction. The metallic pin plate being connected
by well-known means with the general metallic bracing of the instrument, the
accurate fit and secure bearing between the metal surface of the wrest pins and
the pin plate throw the tension of the strings directly on the general metallic
framing, and thus obtain a much more firun and stable resistance than is
possible, when as in the ordinary construction the strain is transmitted through
the wood of the wrest plank. The necessary friction on the pins to prevent
their turning under the strain of the wire is obtained partly by the accurate fit
of the screwed part of the pins into the threads in the metal plate, and partly
by the pressure and elasticity of the wood below. The uniform and smooth
rotary motion of the pin ensured by tapping it is another advantage, as the
operation of the tuner is thereby greatly facilitated. A third advantage is
that the accurate fitting of the pin into the metallic pin plate, as well as into
the wood, retains the pin firmly in its perpendicular position, and prevents it
from twisting or rocking either under the strain of the strings, or the hand of
the tuner. It follows as a consequence of the more stable position of the pin,
and. of the stronger resistance it meets with, that instruments so constructed

page_text: are more durable, and stand better in tune than those strung in the ordinary
way.
In stringing a pianoforte with pins formed on this plan it is necessary so
to wind the wire on the pin as to allow for the descent of the pin when screwed
down, and to prevent the coiled wire from janıming upon the plate. Any
experienced stringer will however accomplish this without difficulty. If pre-
ferred, the screw thread of the pin may be made left handed, so that when
the wire is tightened, the pin will rise out of the plate instead of descending
into it, by which the necessity for the above-mentioned precaution is removed.
Fig. 1 shews the application of this arrangement to the first kind of pins
herein-before named.
In grand pianofortes and other cases where the construction will allow, I
prefer to make the pin plate of a compound or bent shape, by which I obtain
much additional strength. Fig. 3 shows a section of this modification as
adapted to the grand pianoforte. It will be seen that the pin plate B is
of the shape of the letter L, having a return piece B' perpendicular to the flat
part where the pins enter. This return piece being of suitable thickness
supplies the place of what is ordinarily a separate bar called the sweep bar,
against which the longitudinal iron braces take their abutment.
But by
combining this in one piece with the pin plate I not only much strengthen
the wrest plank in all directions, enabling it to resist the various strains and
distorting actions caused by the tension of the strings, but I obtain a firm
and solid abutment for the ends of the longitudinal bars, and by causing the
plate to become an integral part of the system of metallic bracing, I add much
to the stability of the instrument generally.
Fig. 4 shews an application of the same principle to an upright pianoforte.
A is the wrest plank; B, the pin plate; B', the return piece; and C the
wrest pin. I also apply my metallic pin plate in conjunction with another
mode of inserting the wrest pins shewn in Figures 5 and 6. D is a small
plug of hard wood called a "pin plug," which is driven into a hole drilled for
the purpose through both the metallic pin plate, and the wood below,
being secured into its place by cement or glue. The wrest pin C, which is
bere of the ordinary kind, is driven into this pin plug in the same manner as
into the ordinary wooden wrest plank, but the fit of the plug into the iron
gives it greatly increased stability. In order to prevent the pin plug from
turning round in its hole, I make with a file, or by any convenient means,
one or more notches, grooves, or other irregularities in the iron plate repre-
sented by d, d, d, in Fig. 6. When the plug is driven in the wood adapts
itself to these notches, and the plug is thus prevented from moving round

page_text: when the wrest pin is turned. Also in order further to secure the pin plug
I slightly compress it by any convenient mechanical means before it is driven
in, so that the subsequent application of slight moisture (which will be suffi-
ciently obtained by the glue), will cause the wood to swell, and so to hold
very tight in its hole. By effecting this compression in a mould of suitable
form, I can leave projections upon the pin to fit into the small notches d, d, d,
in the plate before described, and I can further make on the pin one or more
grooves or channels (shewn at e, e, in Fig. 6), by which the air may escape
in the act of driving. The two above-named contrivances for holding the
plug firmly in its place, namely, the notching of the hole and the compression
of the wood plug, are applicable also to the case where wood plugs of this
description are inserted into wrest blocks formed entirely of metal.
Having now set forth the nature of my Invention of "Improvements in the
Construction of Pianofortes," and explained the manner of carrying the same
into effect, I wish it to be understood that I do not claim generally the
covering of wrest planks with metallic plates, this having been done before;
neither do I claim the insertion of wood plugs to receive ordinary tuning
pins; but what I claim under the above in part recited Letters Patent is,-
First, the insertion of screwed wrest pins into plated wrest planks, in tho
manner and for the purpose berein-before described.
Secondly, forming metallic pin plates of a bent or compound shape as
shewn in Figures 3 and 4.
And, thirdly, the mode herein-before described of fixing and retaining
wooden pin plugs firmly in their places by compressing the plugs before
driving, and by forming notches or irregularities in the holes.
In witness whereof, I, the said Henry Fowler Broadwood, have hereunto
set my hand and seal, the Twenty-first day of October, in the year of
our Lord One thousand eight hundred and sixty-two.
Witness,
JOSEPH MOUNTAIN,
Servant to the above,
Pavilion, Melrose,
Scotland.
H. F. BROADWOOD. (L.S.)