CERTAIN IMPROVEMENTS ON PIANOPORTES
Year: 1827

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
DETTMER, of Upper Marylebone Street, Fitzroy Square, in the County of
Middlesex, Pianoforte Maker, send greeting.
:
WHEREAS His present most, Excellent Majesty King George the Fourth
did, by His Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Thirtieth day of August, One thousand eight hundred and
twenty-seven, in the eighth year of His reign, give and grant unto me, tlie
said William Dettmer, His especial licence, sole privilege and authority, that
I, the said William Dettmer, my exors, admors, and assigns, and such, others
as I, the said William Dettmer, my exors, admors, or assigns, should at any
time agreed with, and no others, from time to time and at all times during
the term of years therein mentioned, should and lawfully might make, use,
exercise, and vend, within England, Wales, and the Town of Berwick-upon-
Tweed, my Invention of "CERTAIN IMPROVEMENTS ON PIANOPORTES ;" in which
said Letters Patent there is contained a proviso, that I, the said William
Dettmer, shall causė a. particular description of the nature of my said Inven-
tion, and in what manner the same is to be performed, to be inrolled in His
Majesty's High Court of Chancery within six calendar months nèxt and imme-
diately after the date of the said in part récited Letters Patent, as in and by
the same, reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
William Dettmer, do hereby declare the nature of my said Invention to con
sist in so constructing pianofortes as to allow of the pitch to which they may

page_text: have been tuned being altered, and made higher or lower, both in grand and
square pianofortes, at pleasure, by a short and simple process, instead of the long
and tedious one formerly resorted to, of altering the pitch of each individual
wire in succession. And in further compliance with the said proviso, I, the said
William Dettmer, do hereby describe the manner in which my said Invention
is to be performed, by the following description thereof, reference being had
to the Drawing annexed, and the figures and letters marked thereon (that is to
say)-
I make one or both of the two blocks or planks between which the strings
are stretched moveable in the direction of the tension of the springs to a suffi-
cient degree to produce the desired effect, and retaining such block or blocks
or plank or planks in their required position by screws and other mechanical
contrivances, as will be herein-after described or referred to. Altho' I say,
as above, that one or both of the end blocks or planks made be made move-
able, and reserve to. myself the right of moving either or both of them as part
of my Invention, yet on account of the great tension of all the strings drawing
together and in nearly the same direction in a pianoforte that is 'timed to
concert pitch, and the necessity that exists of making.every such instrument
as firm, stiff, and inflexible as possible, in order that it may stand in tune, and
which it could not do if it were liable to any casual change of form or dimen-
sions, I find it best in practice to make one block only moveable, and that
may be either the rest-pin block or plank or the hitch-pin block, according to
the form and construction of the instrument, and the facility of getting at and
moving the said parts; thus, in the grand pianoforte, the wrest-pin plank, or
that solid piece running across the front of the instrument and into which the
tuning pins are inserted, is alone moveable, and the other ends. of the strings
are affixed to the hitch-pin belt block or moulding, which is a strong curved
piece of timber, of sufficient width to receive the said hitch pins and other
.apparatus, to be herein-after described, and to give sufficient strength to the
external case of the instrument, of which this belt block or moulding forms a
part, as will hereafter appear, while, from the different arrangement of parts
necessary in the square pianoforte, the wrest-pin block is stationary, and of
the usual construction in instruments of that kind; and the hitch-pin block,
whether the same be of the modern angular or bent, form, or of the former
straight but oblique shape, are made out with a projection of iron to carry
the hitch pins, as sometimes practised, is made moveable in the direction of the
draught or tension of the strings. I find that a motion of less than a quarter
of an inch is amply sufficient to answer every purpose required in both kinds
of instrument, and this motion I provide for and produce as follows:-.

page_text: And first, in the grand pianoforte.-The wrest-pin block or plank is made
as thick as possible, so as to admit the hammers and various other parts
of the action or key. movement to slide in underneath it, and its block or
thick front part extends to the top of the case. In width it is the same
as usual constructed; and extends from the name board to the cavity through
which the hammers and dampers rise and act. This wrest-pin plank or
block may also be strengthened or stiffened by a bar or bars of iron
attached to its front side, under the veneer, or in any other place where
it will not prove unsightly, because it is necessary to prevent its bending,
casting, or warping as effectually as possible. Instead, however, of fixing
this wrest-pin plank or block firmly and permanently to the two sides of
the case, as has been hitherto done in the construction of grand pianofortes,
I make its length such that it will fitt in very correctly and exactly between
the said two sides, and I attack it thereto by means of a sliding dovetail joint,
made in brass or iron, as shown by the annexed Drawing at Fig. 1; in which
a, b, is a metal plate, of the same lengtli from a to b' as the width of the said"
wrest-pin plank or block from back to front; this plate a; b, carry the dovetail
projection c, c; and e, e, are two detached metal plates, having their inner edges:
chamfered down to fit upon the dovetailed' projection, which they are made
to do very accurately by adjustment upon the two cross pieces of metal f, f,
to which they are then fixed by screws or rivetts; in this way a sliding dove-
tail joint is formed, which, when viewed from the end 6 of Fig. 1, will assume
the appearance of Fig. 2, in which the same letters of reference denote the
same parts. One of these sliding dovetail joints is fixed by screws to each
end of the wrest-pin block aforesaid, (that is to say) one of the plates a, b, is
let in flush with each end of such block, and firmly fixed to it by strong
screws, the projecting ledge d, being let in underneath the said wrest-pin block
and screwed to it in like manner; a pair of the plates e, e, are also let into
and firmly screwed to each side of the case of the instrument in such
manner that the said wrest-pin block may slide backwards and forwards in an
horizontal position in the said dovetailed sliding joints through a space of
about a quarter of an inch; and this sliding, motion of the wrest-pin block
in grand pianofortes provided for and produced as aforesaid is one of the
essential points of my Invention, which I claim under my herein-before in-
part recited Patent.
In providing for the sliding motion herein-before mentioned, I have described
the projection c, c, and the groove in which it moves, as of a dovetailed form,.
because it is the best, inasmuch as it ties the two sides of the instrument to the
two ends of the wrest-pin block, and thus unites all the parts firmly together.

page_text: 9.
Having thus shewn how the necessary motion of the wrest-pin plank or
block of a grand pianoforte may be provided for, I shall in the next
place point out how the necessary motion is to be produced and brought
about, and this may be effected in several ways; but after many experi-
ments I find the application of screws acting through the wrest-pin plank
or block itself aganist the belly rail, when properly braced, strengthened,
and prepared to resist the pressure, or else applied abovo the wrest-pin
block, and likewise above the wires of the instrument by proper metal
bracing, to receive and transmit such pressure over the whole case, to be
the best and most effectual applications. The first of these arrangements is
shewn at Fig. 3, which is the ground plan of the case of a grand pianoforte
before the belly and other parts are fixed, in order to show the framing, and
means which I adopt to stiffen and strengthen the case, and provide for the
motion aforesaid. The belly rail, or transverse bar of wood that supports the
wide end of the belly, and by which the two sides of the instrument are mainly
braced and held together, is shewn at g, g; and this rail I make thicker than
usual, and as it may extend quite to the bottom of the case it admits of very
considerable strength; in order to render it still stronger, I apply the three
braces h, i, k, so placed as to divide the length of the belly rail g, g, into five
equal parts with the usual short brace 1, which is generally used in these instru-
ments. These braces h, i, k, are inch and half boards, placed with their edges
upwards, and of a width fully equal to that of the belly rail into which they
are framed; the extreme end of h goes to the end of the back of the instru-
ment, so as to take advantage of its longitudinal strength; and the brace k
may be stronger than the others with advantage, because it lies under a great
part of the hitch-pin block or belt, and in that part of it which is subject to
the greatest strain or 'tension of the strings. These braces are, kept from
bending by their being let into and intersected by the transverse braces m, m,
which have usually been employed in all instruments. The wrest-pin-plank or
block is shewn in its proper place at n, n, and it is made to slide at its two
ends, as herein-before described. It is further strengthened by a bar of
wrought iron or brass o, o, a full quarter of an inch thick, and of a width
equal to the entire thickness of the wrest-pin plank or block, and has more-
over a return or ledge, like d in Fig. 1, and being most firmly screwed to
the said plank or block, it vary effectually prevents its warping or casting.
Eight holes of about half an inch in diameter are bored thro' the width of
the block; as at p, p, PPP, p, p,p, for the purpose of receiving a like number
of steel or iron screws with fine threads, which pass through tapped holes in
the metal plate o, o; the ends of the screws next to p, P. P. P.P. P, P, P, are

page_text: square, in order that they may be turned round when required by the socket.
key of the tuneing hammer, or other socket key for the purpose, which must
be introduced into the holes at p, p, p, p, p, p. p. p. The other ends of the
screws are conical points of hardened steel, which might act against an iron
plate fixed on the front of the belly rail to receive it, but that there would not
be room for the hammers and dampers to act, on account of the thickness.
of the screws if they projected through. On this account I ani under the
necessity of introducing a framing of iron'q, q, as an intermediate pièce between?
the ends of the screws p, p, &c. and the belly rail g, g. This iron framing is
drawn separately at Fig. 4, and consists of two plates r and s of wrought iron
or brass, about a quarter of an inch thick and an inch and balf wide. "They aro
united together at a sufficient distance to allow the hammers and dampers to
act between them by the cross pieces q, q, &c., which being. of the same depth
as 'the two plates, will be sufficiently strong if they are the eighth of an inch
in thickness, and thus ample room will be left for the hammers and dampers,
which must, liowever, be set out as well as the wires, according to the scale:
or manner formerly used when short iron arches were made use of in tho
grand pianofortes. The two cross pieces 9, 9, at the extreme ends of the
frame may, however, be made stronger, to prevent the frame getting out of
square, because they will both fall beyond the strings. The use of this iron
frame is obvious; the back plate s is firmly screwed in front of the belly rail
9, g, which it serves to brace and strengthen, and the plate receives the
points p, p, of the screws, one coming against each transverse piece q, q,
order 'to secure a direct pressure and greater force without liability to bend';
whenever, therefore, the screws p, p, &c. are turned inwards, they will press
against the plater and 'cause the whole wrest-pin plank or block to recede,
thereby tightening all the wires of the instrument, and consequently raising
its pitch, and by turning them the contrary way and relaxing them in' tension
and elasticity of the wires will draw the wrest-pin plank or block inwards and
lower the pitch of the instrument. I have, as above mentioned, eight screws
as passing through the wrest-pin plánk or block for this purpose, whereas it'
may appear that a less number of them would answer the purpose; their
number must, however, 'depend upon the extent of the scale of the instrument,
because, although a smaller number would suffice to move the wrest-pin
plank, or block, yet I find that when more than an octave is contained between
two adjacent screws that the motion is not sufficiently under controul to main-
tain the instrument in tune, and consequently that it is desirable to introduce a
screw at every octave in the grand pianoforte. The keyholes for getting at the
screws 'in' front of the wrest-pin block I cover or conceal by a front or name
in

page_text: board, or in any other ornamental way that will prevent their being seen or
touched except when required. In the square pianoforte, to which my said
Invention and improvements also apply, its form and construction prevents the
wrest-pin block from being made moveable in a simple and eficient manner,
and in this form of instrument I therefore cause the hitch-pin block to
move, as herein-after explained.
:
Figure 5 in the annexed Drawing, represents the manner in which I apply
my aforesaid Invention and improvement to the square pianoforte. A, A, A, A,
is a plan of the case of the instrument, which with the wrest-pin block n, n,
is on the usual construction. The hitch-pin block is shewn at b, u, t, being
in modern instruments usually bent into an angular form at u, but whether
in.this form or in the straight. form running obliquely across the instrument,
as formerly used, and as shewn by the, red lines W, W, or with an iron
plate to carry the hitch pins, my principles of construction equally apply.
The hitch-pin block as usually constructed is supported upon a timber bed,
similar in form to itself, and extending to the bottom of the instrument.
In my construction I make the hitch-pin block about two inches thick,
and detached from the bed underneath it, so that it is free to move. The
top of the bed and the bottom of the hitch-pin block are, however, made
smooth, and to coincide in a truly horizontal position, and I unite them
together by metal dovetail sliding joints, such as have been herein-before
described by Figs. 1 & 2, except that they are without the ledge or return d.
Dovetail plates, like a, b, are let into 'and screwed upon the under side of the
hitch-pin block at the three places marked t, t, t, and the corresponding plates
e, e, to form the sliders, are also let into and screwed upon the wooden bed under
the block. These sliding joints are not placed parallel to the back and front
of the instrument, but in the direction of the metal braces; V, X, V, X, V, X,
&c., to be afterwards described, and as may be seen at t, t, t, where they are
shewn by dotted lines. These sliding joints so fixed and prepared not only
serve to hold the hitch-pin block down in its place, but also allow of its
moving backwards and forwards in a sufficient degree to alter the pitch of
the instrument, as aforesaid. In order to allow of this motion, care must be
taken to allow sufficient space between the back end of the hitch-pin block
and the back of the instrument, because if this is not done it will bind against
the back as it advances, on account of the direction of its motion. The tension
of the wires will always draw the hitch-pin block forwards, consequently the
only thing to be provided for is a sufficient power to drive or move it back-
wards, and this I obtain by the metal braces V, X, V, X, V; X, V, X, which
are placed as short a distance as possible (so as to be out of the way) above

page_text: the wires. One end of each of these braces fits by a tongue or tenon of metal
into one of the metal brackets or buttresses y, y, y, y, which are firmly
bolted down to the wrest-pin block n, n, and the other end of each brace is
equipped with a screw, as at z, z, z, z, having a four, six, or eight canted
head for turning it, and a conical steel point projecting beyond its head to
press against other metal brackets or buttresses C, C, C, C, which are let in
and firmly bolted down to the hitch-pin block för the purpose of receiving such
pressure. One of these screws, together with the bracket or buttresses and
the end of a metal brace, is shewn of about half its real size at Fig. 6; and
D is a key or wrench made.to fit on to the heads of all the screws in common
for the purpose of turning them. The operation of this machinery will be
evident on inspection of the Drawing, for since the hitch-pin block is separate.
and detached, not only from the belly of the instrument but from its case,
also so upon turning the screws 2,2,2,2, tho said hitch-pin block can be
moved nearer or further from the wrest-pin block; and the pitch of the instru-
ment be varied accordingly. The several screws will not require to be turned
in an equal degree, because a much smaller quantity of motion will suffice for
the treble than for the base wires, but by trying the notes while turning the.
screws there will be no difficulty in keeping the instrument in tune, or re-
storing it to the tune, if deranged by the operation, provided it was in tune in
the first instance. It may be necessary to observe, that in first stringing the
instrument the hitch-pin block must be set nearly as far as it will go from the
wrest-pin block, because the tension of the strings will draw it up a little, and
if this precaution was not attended to the tension of the strings might break
or strain the belly, and would likewise prevent the pitch of the instrument
being lowered, although it would not interfere with its being raised. In
fixing the aforesaid brackets or buttresses, I generally use screw bolts made
on purpose, or such bolts in combination with the best finished carpenter's
wood screws, but whenever they occur I always place the heads or the nuts
uppermost, so as to admit of the brackets or buttresses being taken off with.
facility in case of derangement or accident; and as the two longest braces
cover a portion of the wrest-pin block in which tuning pins should be placed,
but which could not be got at without great inconvenience, so I find it better
to place eight hitch pins in two rows under each of such longest braces in the
wrest-pin block, and to put a corresponding number of wrest pins in the hitch-
pin block, as at E, E, by which all inconvenience in tuning the instrument is
avoided. I likewise find it necessary to shorten the heads of those dampers
that work under the said braces, in order to prevent their striking against the
same and producing a noise.

page_text: Fig. 7 represents the means which I use to apply the same kind of bracing
to a grand pianoforte, in which the wrest-pin plank or block n, n, is made
moveable by end sliders; as detailed in the description of Fig. 1, and which is
in every respect constructed as before described, except that instead of boring
holes through it to admit the screw's to produce its motion, those screws and
holes are altogether omitted, and' in lieu of them I apply the eight brackets'
or buttresses upon the top of the said wrest-pin plank or block, taking care
to let them into the wood of the same, and to bolt or screw them firmly down
to it. These brackets are for the purpose of receiving the points of the
screws', z, z, z, &c.; and are, together" with the braces, exactly the same in
construction and for the same purpose of resisting the tension of the strings,
as in the square pianoforte herein-before described. From the greater length,
however, of the braces necessary in the grand pianoforte over the bass wires,"
I find it expedient to divide that length into two parts in this portion of the
instrument, and this I do by introducing the square bar of iron or otlier metal
F, F, across the case from one side to the other, where I confine it by wooden'
cleats or blocks, behind or beyond this block; the metal braces proceed in the
same right-lined direction as the front ones' to the end bent side of the instru-'
ment, and for the sake of their better adjustment I introduce screws at their
ends z,,,, which bear or 'press against the cross bar FF: The tongues:
or tenons of the four front bass braces enter mortice holes made in this cross
bar to receive them, and the extreme ends of all the braces have similar
tongues or tenons, which enter into the metal brackets or buttresses y, y, y, &c.,
which are let into and firmly bolted down or screwed upon the curved belt
moulding or block G, G, G, which serves as the hitch-pin block 'of the instru-
ment; and with a view to render this block more firm and solid and less liable
to change of form than it has hitherto been made, I do not attach it to the
inside of the case, but I make it part of the case'itself, and to proceed through'
the whole thickness of such case, it being only hidden on the outside by the
veneer; and instead of using an entire board for the curved part of the case,
the upper part of it, that is, the part above the belly, is built or fixed upon.
this solid wrest-pin block or belt, and the under part is attached in like
manner to the underside of it, so that a vertical section thro' any curved part
of the case, as in the direction of the line HH, would have the appearance
shewn in Fig. 8, where G, G, is a section of the hitch-pin block; I, the upper
part, and K, the under part of the case, the whole external surface of
which is covered by the veneer L, L. The metal braces above described may
be square or round, or ornamented, and made of any material that is suffi-
ciently stiff and strong to effectually resist the tension of the strings; what

page_text: I generally use is iron, and to improve their appearance I either gild such
iron or cause it to be covered with thin lacquered brass, or if not so
covered, I brown or bronze it, like the barrels of fowling-pieces, to preserve
them from rust; the end brackets or buttresses y, y, y, y, &c. I generally
make of brass, but iron will do as well, and the resisting brackets or
buttresses,,,, &c. I uniformly make, of cast or wrought.iron. It may
here be observed, that from the great tension of all the wires upon the wrest-pin
plank or block, it will have a tendency to rise on its central part and loose.
its truly plane or right-lined form, which tendency must, be counteracted; and
this I effect by screwing down each of the metal braces V, X, V, X, V, X, &c.
at the points marked V, V. These screws pass downwards through the
belly rail, and by turning their nuts by a spanner at its under side the said
braces may be drawn down towards the belly with any required force. These
screws pass thro' holes in the belly without touching it, so that its vibration
is nowise impeded by them. It will also be advisable to stiffen the said
wrest-pin block by a bar of iron let into and screwed to its front edge under
the veneer, or to both the back and front edge, according as circumstances
may require; and with a view to the further prevention of the wrest-pin block
from rising, I recommend that the brackets or buttresses placed upon it should
be continued thro' or else have tails extending thro' to the thick block always
formed in the front. part of the said wrest-pin plank or block, as shewn at
M, M, M, in Fig. 7, or in the separate view of one of the said brackets or
buttresses at Fig. 9, in order. that the direct line of pressure of the screws
and metal braces may be continued through to the front or strong part of the
wrest-pin block M, M, M. When the metal braces now last described are
resorted to in the grand pianoforte, I omit the timber bracing of the belly
rail, as described by Fig. 3, because no extraordinary strain is exerted upon
that rail.'
Now, whereas it will be seen throughout the whole of my aforesaid de-
scription that my Invention and improvements extend to the bracing and
strengthening of grand and square pianofortes in such manner as to available
for the purposes of the other part of my said improvements, viz', that of altering
the pitch of an instrument when in tune in manner aforesaid; and whereas the
constructions that I have herein-before described are those which I now use
and believe to be the best; but it will be obvious to any mechanic that many
changes may be made in the form and application of the apparatus without
deviating from the principles of my Invention, which I hereby declare to be
the rendering one or both of the blocks to which the ends of the wires in
grand and square pianofortes are attached capable of receiving motion in a

page_text: horizontal direction, as aforesaid, so that I can alter the pitch of a grand or
square pianoforte by moving the said blocks at pleasure, whether the same be
effected by screws, as herein-before described, or by wedged levers, or other
mechanical means;, as also the stiffening or bracing of the cases of instru-
ments so constructed by wooden or metal braces, applied as aforesaid, for the
purpose of. enabling them to sustain the pressure necessarily exerted in thus
altering the pitch of the instrument; and such my Invention being, to the best
of my belief, entirely new, and never before used in that part of His said
Majesty's United Kingdom of Great Britain and Ireland called England, His
Dominion of Wales, and Town of Berwick-upon-Tweed, I claim as aforesaid.
In witness whereof, I, the said William Dettmer, have hereunto set my
hand and seal, this Twenty-ninth day of February, in the year of our
Lord One thousand eight hundred and twenty-eight.
AND BE IT REMEMBERED, that on the Twenty-ninth day of February,
in the year of our Lord 1828, the aforesaid William Dettmer 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 tho
tenor of the Statute made for that purpose.
Inrolled the Twenty-ninth day of February, in the year of our Lord One
thousand eight hundred and twenty-eight.