Year: 1897

page_text: I, JOHANN CARL HEINRICH SCHNELL, of 46, Gurlittstrasse, Hamburg, in the Empire
of Germany, Piano Manufacturer, do hereby declare the nature of this invention to
be as follows:-
The strengthening of the frames of pianos rendered necessary by the augmentation
P.of the wires of the instrument introduced some time back was effected by the
employment of iron plates in their construction. This, however, imparts a metallic
character to the tones produced and only instruments which produce a wood tone
possess a pure timbre.
The object of this invention is to render this prejudicial influence of the iron
plates quite innocuous, and this result is obtained by using a double resonance
bottom comprising two plates divided interiorly by means of ribs into longitudinal
divisions or compartments, one of such plates being furnished with sound
holes.
i
Contrary to what is the case in double resonance bottoms as hitherto made, the
ribs here form, up to their slightly inclined or bevelled ends, 'partitions and at the
same time connections between the two bottom plates, so that when the instrument
is played, a number of vibrating air columns exist within hollow resonating wooden
passages, and the two bottom plates as a result of their numerous connections vibrate
in unison. By means of the sound holes, the vibrating layers of air within the
I double bottom are placed in communication with the outer air.
6
'I, JOHANN CARL HEINRICH SCHNELL, of 46, Gurlittstrasse, Hamburg, in the Empire
of Germany, Piano Manufacturer, 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 → :
The present invention relates to improvements in pianos and the like and 'more
077

page_text: especially refers to improvements in double resonance bottoms for such instruments
the same being designed to take the place of the ordinary soundboard.
The strengthening of the frames of pianos rendered necessary by the augmentation
of the wires of the instrument introduced some time back was effected by the
employment of iron plates in their construction. This, however, imparts a metallic
character to the tones produced and only instruments which produce a wood tone
possess a pure timbre.
The object of this invention is to render this prejudicial influence of the iron plates
quite innocuous, and this result is obtained by using a double resonance bottom
comprising two plates divided interiorly by means of ribs into longitudinal divisions 1
or compartments, one of such plates being furnished with sound holes.
In order that my invention may be more fully understood I will now proceed to
describe the same in detail and for that purpose shall refer to the accompanying
drawing, in which :-
Figure 1 is a bottom view of my improved double resonance bottom as it appears 1
after the removal of the bottom plate proper;
Figure 2 is a plan of the top plate;
Figure 3 is a section on the line 3-3 (Fig. 1).
Figure 4 is a section on the line 4-4 (Fig. 1).
Figure 5 is a similar view to Fig. 1 showing a modification, the bottom plate, not
being removed; and
Figure 6 is a section on the line 6-6 (Fig. 5).
As will be evident from the drawing the present double resonance bottom consists
of a top (or front) plate a¹, a bottom (or rear plate) a² and suitable side walls a³
arranged and connected so as to form a flat box-like casing. The ordinary double
resonance bottom thus obtained is divided interiorly by means of ribs b into
longitudinal divisions or compartments. One of the plates a¹ or a², in the present
case the plate a¹, is furnished with sound holes c; the plate a¹, moreover being.
provided on both its sides with corresponding cross ribs d and d¹ respectively.
Contrary to what is the case in double resonance bottoms as hitherto made, the
ribs b here form, up to their slightly inclined or bevelled ends 6', partitions and at
the same time connections between the two plates a¹ and a², so that when the
instrument is played, a number of vibrating air columns exist within hollow resonating
wooden channels and the two plates as a result of their numerous connections vibrate
in unison. By means of the sound holes c, the vibrating layers of air within the
double resonance bottom are placed in communication with the outer air.
In the above described construction of my improved double resonance bottom the
vibrating air columns communicate with one another through the passages formed by
the cut-away portions or bevelled ends b¹ of the ribs b (see Figs. 1 and 4). In
Figs. 5 and 6 I have shown a modification, in which the said air columns are entirely
or wholly separated from each other. This result is obtained by special ribs e placed
between the ribs b at those places from which the bevelled ends b¹ extend. In this
form of construction which gives a still better effect than the constructional form
represented by Fig. 1-4, it is not necessary that the plate a² corresponds in size
with the plate a¹, the purpose of better effect will be obtained even if the said plate a²,
as illustrated in Figs. 5 and 6, covers only the space or those parts of the channels
enclosed or surrounded by the cross ribs e.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what, I
claim is :-
1. The hereindescribed improved double resonance bottom for pianos and like
instruments thereby characterized that the bottom plates (al a²) are connected by a
plurality of ribs (b), so as to form in the interior of the double resonance bottom
longitudinal air chambers communicating with one another through passages at the
ends of the ribs (b) and with the outer air through suitable sound holes (c) substantially
as and for the purpose set forth.

page_text: 2. The hereindescribed modification of the improved double resonance bottom in
which the longitudinal air chambers are wholly separated from one another by means
of suitable cross ribs (e), substantially as and for the purpose specified.
Dated this 22nd day of December 1897.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.