THE IMPROVEMENT OF THE MANUFACTURE OF PIANOFORTES.
Year: 1854

page_text: LETTERS PATENT to William Porter Dreaper, of Bold Street, Liverpool,
in the County of Lancaster, Pianoforte Manufacturer, for the Invention
of "THE IMPROVEMENT OF THE MANUFACTURE OF PIANOFORTES.
Sealed the 5th April 1855, and dated the 19th December 1854.
PROVISIONAL SPECIFICATION left by the said William Porter Dreaper at
the Office of the Commissioners of Patents, with his Petition, on the
19th December 1854.
I, WILLIAM PORTER DREAPER, of Bold Street, Liverpool, in the County of
Lancaster, Pianoforte Manufacturer, do hereby declare the nature of the
said Invention for "THE IMPROVEMENT OF THE MANUFACTURE OF PIANOFORTES,"
to be as follows:-
The down bearing of the string on the sounding board, which is the incon-
venience to be remedied, is shewn by Figure 1, which is a section of a cottage
pianaforte, shewing the down bearing of the strings. A, A, the bridges; B,
the sounding board or belly; C, the string, extending from the tuning pin D
in the wrest plank to the lutch pin E in the lutch block at the bottom. The
inclined lines at each end from the wrest plank bridge A to the tuning pin D,
and from the belly bridge A to the lutch pin E, will shew the down bearing of
the strings, which is of necessity in every pianaforte, to cause the strings
to lie or press solidly on the bridges to insure a solid tone, otherwise it
would be a jar.

page_text: Figure 2 shews the result of the continued down bearing or pressure on the
bridge & belly; the dotted lines shew the sinking of the belly from a straight
line (similar to a drum head), which is the proper position for the belly; when
it sinks below that and forms a curve line, the vibration becomes imperfect,
and the tone much impaired.
The only means that have hitherto been used as a counteraction to the down
bearing is the bar of wood F, in Figure 1, which is glued to the under side of
the belly. A belly is generally supported by from 6 to 11 of such bars, which
in all cases, more or less, yield to the continued down pressure of the strings;
hence the quality of tone in a new instrument is so much better than in an old
one, or, in other words, the straight line position of the belly is less impaired
at first than in after time. To more effectually counteract the down pressure,
I use my new Invention, which I call a compensation bar, which is shewn in
Figure 3, colored lake, & is fitted with a tennant into the mortice block G,
pressing against the original bar of the belly at H by a sound block or post, and
at I, regulated by a wood screw or sound post, which causes the pressure at H
to retain the original bar and belly in its proper straight line position; I use a
compensating bar generally to each of the original bars. And my improvement
consists in the mode in which the compensating bar is applied, it being not as
the old bars are, attached by glue to the belly throughout its whole length,
but merely coming into contact with the belly at the point H, by means of
the sound block, whereby the elasticity of the belly is much increased, and
the quality and power of the tone greatly improved. For the bass and tenor
parts of the instrument I use a hollow bar on the same principle, which is
shewn on Figure 4; being less solid and more sonorous, is better adapted to
the bass and tenor parts, and the bar in Figure 3 to the parts from the tenor
to the treble.
The great utility in the compensating bar is, that it supports the sounding
board in its proper straight line position, relieving it from the effects of the
down pressure, and thereby greatly improving its vibratory qualities, causing
the tone to come out with freedom and power, and to continue in duration
one-fourth longer than before having the compensation bar applied. In the
new instrument it is a preventive, and in the old a remedy, against the sinking
of the sound board.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Porter Dreaper in the Great Seal Patent Office on
the 21st May 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
PORTER DREAPER, of Bold Street, Liverpool, in the County of Lancaster,
Pianoforte Manufacturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Nineteenth day of December, in the year of our
Lord One thousand eight hundred and fifty-four, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said William Porter Dreaper, Her special licence that I, the said William
Porter Dreaper, my executors, administrators, and assigns, or such others as I,
the said William Porter Dreaper, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and at all
times thereaftér 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 "THE
IMPROVEMENT OF THE MANUFACTURE OF PIANOFORTES," upon the condition (amongst
others) that I, the said William Porter Dreaper, by an instrument 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 William Porter Dreaper, 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):-
:-
This Invention has for its object means of counteracting the pressure caused
by strings on the sound boards of pianofortes, and consists of the application
of what I call compensation bars and generators of sound to the ordinary
sound boards and bars of pianofortes.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a transverse section of an upright pianoforte, and Figure 2 is a
back view thereof. a, a, is the sound board; b, b, are bars, which are glued
from end to end of their length at the back of the sound board. These parts
are, as is well known, of the ordinary construction; but I may remark that

page_text: when a sound board of a pianoforte is simply strengthened by such fixed bars
b, b, it is liable to be deflected out of its true or correct form, particularly where
the strings press on the bridge, which is fixed to the sound board. c, c, are
bars applied to the back of the sound board, in such manner as to compensate
for the pressure of the strings on the bridge, which is fixed on the sound
board; these bars c, which I call compensating bars, may be varied in their
forms, and applied differently to the sound boards, so long as the points of
contact are arranged suitably for giving support to the sound boards, and to
prevent the sound board being deflected by the pressure of the strings on the
bridges, fixed to the sound boards, and they may, when preferred, be made
hollow, so as to be generators of sound. The forms of compensating bar c,
which are preferred, are shown at Figures 1 and 2, and on a larger scale at
Figures 3 and 4; some of these compensating bars c consist each of a bent
fillet of wood (1), glued on to two side pieces (2), which are at right angles to
the fillet (1). At the lower end of the compensating bar c, shown in Figure 1,
there is a closing in of the front lower part for some distance to form a short
belly, and the block c¹ (which comes in contact with the fixed bar b) is fixed
or glued to this belly or front, as shown, and is pressed against the back of one
of the bars 6 of the sound board a, so as to sustain it near the bridge, and near
where the pressure of the strings is most severe. The upper end of the com-
pensating bar c rests under the clip or stop d, and the compensating bar c is
set up to and is made to sustain the sound board by means of screws e, e,
which I prefer to be of wood. These screws pass through fixed nuts f,f, at
the back, as shown. In Figure 2 there are three such compensating bars c
shown, each pressed up by two screws at back.
The other four compensating bars c, shown in Figure 2, differ from those
above described, but it is not essential that different forms of compensating
bars should be used in a piano, as all the compensating bars in a piano-
forte may be alike. These four bars c are made hollow, thus forming sound
chambers, as well as bars c, which I prefer to be the case for the higher notes.
The construction of these four bars are similar to the one shown in section at
Figure 5, and back view at Figure 6. In this construction c, c, are two bars,
connected at their lower ends by the cross bar c*, against which the screw e
presses. (3) is a portion of the bar, made of wood, of the form shown, having
a sound post or support at (4), and the bar c presses against the bar 6 of the
sound board a at the point c'. The hollow portion (3) of the compensating
bar is connected to the bars c, c, at the point (5), by screws passing through
the cross piece of wood, as shewn. I have above stated that the forms of the
compensating bars may be greatly varied, and I would observe that I make no

page_text: claim to any particular form, nor do I confine myself to the forms of compen-
sating bars shown, my Invention not being in the form or construction of the
bars c themselves, but consists of applying compensating bars (whether they
be generators of sound or not), as herein described. And I prefer in each case
that the point of contact c¹ of a compensating bar c, with the sounding board a,
should be near to but not directly at the back of the sounding board, where
the bridge comes. And although I have shown and recommend only one
point of contact between a compensating bar c and the sound board, this may
be varied.
Figures 7 and 8 show sections of other forms of compensating bars c which
I have used, but I am not aware the effect produced by them differs from
those before described. The compensating bar c, Figure 7, differs but little
from the one shown in the previous Figure, and principally in having the
upper end closed, and in the use of the diagonal, or stay or strut (6), at its
lower end. In Figure 8 the compensating bar c is for the most part hollow,
as shown, and has not separate bars c. In Figure 9 the compensating bar c
is solid, and is made stiff by a rib at the back. I would remark that I recom-
mend the use of solid compensating bars where a bright tone is required,
and those which are more or less hollow where a more mellow tone is
desired.
Having thus described the nature of my said Invention, and the manner of
performing the same, I would have it understood that what I claim is, the
application herein described of compensating bars and generators of sound to
the sound boards and bars of pianofortes.
In witness whereof, I, the said William Porter Dreaper, have hereunto
set my hand and seal, this Ninth day of May, in the year of our
Lord One thousand eight hundred and fifty-five.
Witness,
J. G. TONGUE.
W. P. DREAPER. (L.S.)