IMPROVEMENTS IN THE CONSTRUCTION OF PIANOFORTES
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by William Sweetland at the Office of
the Commissioners of Patents on the 9th November 1878.
WILLIAM SWEETLAND, Organ Builder, 4, Cleveland Place West, Bath, in the
County of Somerset. "IMPROVEMENTS IN THE CONSTRUCTION OF PIANOFORTES."
The nature of my Invention is to add octave couplers, super or sub, which will
increase the volume of tone to double its original power, and which Invention I
believe will be of great public utility, as it will enable the performer at pleasure to
play the most rapid passages in octaves with greater facility.
The following is a description of octave couplers, super or sub:-
A series of diagonal backfalls, squares, or rollers, with hoppers fitted to one end,
or a stud for lifting the under haminer, jack, lever, or upper part of the key, which
key is divided from the centre pin to the back, so that the top part of the key will
lift without moving the front part, thereby not destroying the elasticity of the
touch or interfering with the second octave. The super or sub-octave coupler can
be applied instantaneously to one note or chord at will by two foot pedals, one for
the super the other for the sub-octave, or by studes or knobs made to press in ; the
said knobs to be arranged along the front of the key-slip either under or over the
keys. The two said pedals to be placed side by side so that the performer may be
able to press down one or both pedals with one foot at the same time so that he
would be able to bring on the octave couplers super and sub together. When the
foot is removed from the pedals the pianoforte at once resumes its original
character. I have represented the mechanism of the octave coupler by the annexed
Drawing.
Fig. 1 represents the section of octave coupler, super or sub. A, the pianoforte
key B, original hopper; C, backfalls, lever, or tracker with hopper D on the end;
E, under hammer or lever to be lifted by the two hoppers; F, the backfall or
square beam; G, regulating wire, with book to pull down the front of backfall
or square, also to regulate the hopper D up to the under hammer or lever E;
H, regulating wire to keep backfall or square from dropping on key A when not in
use; I, trundle with lifting arms or wedge to raise the backfall frame, and bring
the coupler movement up to its work; J, trace to foot pedals; T, sticker.

page_text: Fig. 2 represents the ground plan or transverse action, backfall, squares, rollers,
and hoppers. C, the backfalls or squares either over or under the keys; F, the
back fall frame with arm and pivet for hinge S; K, centre for backfalls to work on;
L, studs over or under the keys, made to press in, to put on couplers without the
assistance of foot pedals, as may be most convenient to the performer.
Fig. 3 represents the end of backfall or square, lifting the lever, under hammer,
or jack without a second hopper.
Fig. 4 represents the back part of keys split in two; the top part M is hinged
at N with a stud or sticker passing through the lower part of the key A, so that
when the squares or levers C, O, are lifted it will raise the upper part of the key M,
with the hopper, jack, and all that is on it, and the front part of the key octave
above will remain stationary, so that it does not interfere with the second octave;
F, R, square frames made to slide up and down with foot pedals, or with the
studs Lin front of key-board so as to put on and off the coupler movements. The
frames, backfalls, squares, levers, trackers, and movements to be made of wood or
metal and fixed over or under the key-board according to the construction of the
pianoforte.