Year: 1886

page_text: Date of Application, 10th Dec., 1886.
Specification Accepted, 11th Jan., 1887.
I PHILIP ARTHUR NEWTON of the Office for Patents, 6, Bream's Buildings, Chancery
Lane in the County of Middlesox, Patent Agent, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly described.
and ascertained in and by the following statement :—
In the construction of upright and grand pianos, the frame on which the keys are
supported side by side is usually secured to a broad flat wood plank, which is attached
at the ends to the under sides of arms projecting outward from the case, and is
technically known as the "key-bottom."-By changing seasons and the different and
changing conditions of the atmosphere as to moisture, this wood key-bottom is very
liable to bend or warp both lengthwise and crosswise, and the keys are thereby thrown
out of position to such an extent as to greatly impair the instrument, and interfere
with proper touch and execution in playing.
The object of this invention is to overcome the objections which are inherent in key
bottoms made entirely of wood, and to provide a key-bottom which will maintain its
true flat surface under any atmospheric changes, and always hold the key frame and
keys in proper position.
The invention consists essentially in a key bottom cast metal constructed in a novel
manner hereinafter described and pointed out in the claims.
In the accompanying drawing, Fig. 1 is a transverse section of a key-bottom
embodying the invention, and a key-frame supported thereon. Fig. 2 is a longitudinal
section of the bottom and frame, and Figs. 3 and 4 are respectively a top and inverted
plan of the key-bottom alone.
Similar letters of reference designate corresponding parts in all the Figures.
A, designates the key-bottom, and B the usual key frame supported thereon, and
composed of the front and back bars 6 61, and cross bars 62, and the bar 63 whereon
the keys are fulcrummed. The key-bottom consists of a cast metal plate or frame,
preferably having a truly flat upper surface, which is continuous so far as is necessary

page_text: to support the several bars or rails of the key-frame B. For the sake of lightness,
there are represented openings a at those parts of the key-bottom where no parts of
the key frame rest, and such openings may be closed by boards or wood panels, C
which may be held in place by screws inserted through holes s, in order to prevent
dust from rising through the key-bottom and into the piano.
The plate A is shown as provided on its under side with longitudinal ribs a², which,
as shown, are arranged in pairs on opposite sides of the openings a, and serve to
prevent the plate or bottom from bending or warping in a direction lengthwise thereof.
The plate or bottom is also shewn as having on its under side transverse ribs a³, which
also extend in pairs between the openings a, and join the ribs a¹.
The key-bottom, when constructed as above described, will be very stiff, and-yet
light, and its upper surface, which supports the key frame, will be maintained in its
truly flat condition, and will not be bent or twisted by any atmospheric changes.
The key-bottom is represented as provided with holes s¹ for the insertion of screws
from its under side to secure the key-frame B in place upon it, and with holes &* for
the insertion of screws into the arms of the piano case, for securing the key-bottom
thereto. The key-bottom is shewn as surrounded on the front and ends by a
moulding c, as is usual with wood key-bottoms.
Having now particularly described and ascertained the nature of the said invention,
and in what manner the same is to be performed, as communicated to me by my
foreign correspondents, I declare that what I claim is :-
1. A key-bottom for pianos or similar instruments formed of metal, and provided
with stiffening ribs or flanges, substantially as herein described.
2. A cast metal key bottom for pianos or similar instruments, consisting of a plate
having upon its under side longitudinal strengthening ribs, substantially as herein
described.
3. A cast metal key-bottom for pianos or similar instruments consisting of a plate
having upon its under side longitudinal and transverse strengthening ribs, substantially
as herein described.
4. A cast metal key-bottom for pianos or similar instruments having a flat upper
surface for the support of a key-frame, and having strengthening ribs upon its under
side, substantially as herein described.
5. A cast metal key-bottom for pianos or similar instruments having its upper
surface flat and continuous or unbroken in those portions on which the key-frame is
to rest, and having openings between such portions and strengthening ribs on its
under side, substantially as herein described.
6. The cast metal key-bottom A having a flat upper surface with openings a, and
panels C covering the openings, and having on the under side strengthening ribs a', a²,
substantially as herein described.
NEWTON & SON,
Agents for the Applicant.