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TfclE MUSIC TRADE
REVIEW
ing commentary upon the conservatism and
backwardness of piano manufacturers in the fact
that as yet there seems to be but little tendency
among them to supersede this obsolete and im-
Discussed in a Series of Interesting Papers—The Theory and Practice of Pianoforte Construc-
tion—The Belly Bridge and Sound-Board—The Phenomena of Resonance—Suggestions perfect form.
Doubtless much of the apparent unwillingness
Regarding Construction and Some Pointers Regarding Betterment.
of pianoforte makers to experiment in this direc-
tion rate is synchronous with that of the original tion is due to the fact that the actual function
ARTICLE 5.
sounding string. When such a string is reached of the sound-board is but slightly understood.
The Belly Bridge and Sound-Board.
We have now made a somewhat lengthy and it is immediately impressed with the motions ex- In this department of the instrument, more than
thorough investigation into the nature and be- cited in the former string, with the results above in any other, knowledge of form of construction
havior of the various materials and substances described. This is a case of resonance of two and the processes that occur within it are
that are employed in the construction of piano- attached bodies. Peculiar as it may seem, entirely empirical. It would, indeed, be not
forte strings. Prom this inquiry we have been however, it is not essential that two sono- unjust to say that most manufacturers are quite
able to deduce a set of rules which, when practi- rous bodies be tangibly connected as a prelimi- at sea in regard to the actual phenomena of
cally applied, will furnish us with: a guide to the nary condition to the existence of resonance be- resonance as exhibited within the sound-board.
solution of many perplexing problems which take tween them. For instance, the foregoing experi- Finding that the methods that had sufficed for
their root in the conditions imposed upon the de- ment may be varied by'employing two piano- the early instruments, with their small volume
signer by the limitations of space and the other fortes and choosing one of the notes from each. of tone and low tensions, could be made to serve,
mechanical conditions of pianoforte construction. The result will be precisely the same. It will, the manufacturers have been content to continue
It would not be proper, however, to proceed forth- however, be noted that only such notes as have a similar form in the modern instrument, in
with to the practical questions of string-arrange- either synchronous or nearly synchronous rates spite of the fact that the introduction of iron
ment. For we must still find the correct solu- of vibration will exhibit the phenomena of reso- framing and heavy steel wire has changed the
tions of another series of problems that spring, nance when separated from each other. Where whole problem of encouraging the power of reso-
not from the strings themselves, but from their they are connected, however, especially when the nance. This indifference has led to serious re-
important and necessary accessories, the sound- connecting body is a sound-board prepared for sults. At the present time the effective life of a
board and belly bridges. It may be noted paren- the purpose, synchronism is not necessary. In sound-board is usually terminated by the inevi-
thetically that we have already laid down certain fact, it is a matter of common observation that table splitting that seems invariably and shortly
general propositions in regard to the bearing- the sound-board of the pianoforte, in conjunction to follow the introduction of the piano to
bridges which interpose between the sonorous with the belly-bridge, operates to set up more or the vicissitudes of home use. It is a fact fa-
portions of the strings and the tuning-pins, but less intense vibration in every string within the miliar to all who deal with the pianoforte after
this course was taken because the treatment of compass of the instrument when the dampers it leaves the factory and enters the purchaser's
this particular matter followed naturally and di- are raised, even if only one string be struck. home, that exposure to differences in tempera-
rectly from the main inquiry that we were con- When the damper pedal is raised in playing, ture usually proves too much for the resisting
power of the sound-board construction; it is un-
ducting at the time. The belly bridges and sound-
every string throughout the instrument is imme- able to sustain the burden put upon it; it splits;
board, however, open up new ground for investi-
diately thrown into a state of vibration and be- and its usefulness is forever impaired.
gation and require a separate discussion.
gins to sound. The result is a large augmenta-
Suggestions Toward a Remedy.
The belly-bridge is the medium of connection tion of the total volume of sound produced. Of
The obvious inference to be drawn from a
between the strings and the sound-board. Through course, the sound of any one string thus sympa-
it the vibrations excited in the strings are con- thetically excited is relatively feeble, but the consideration of these somewhat melancholy
veyed to the freely vibrating surface of the total volume is considerable, with especial facts is that the accepted construction is struc-
sound-board, and the sonority of the generated strength in the particular partials of each string turally weak. Experience seems to show that
sounds is thereby enormously increased. This is that are more or less synchronous, as to their the inference is true. Further, it is by no means
the process in bare outline, but, in order to ob- vibration rates, with the notes originally pro- sure that the greatest acoustical efficiency can be
tain a proper view of the matter under discus- duced by striking the keys. When the dampers obtained with such a style of building as has
sion it will be necessary to examine the phe- are permitted to rest in their normal positions, been described. Of course, the area of vibrating
nomena to which the juxtaposition of string, on the other hand, the sound-board exercises its surface is necessarily circumscribed within the
bridge and sound-board give rise. We must, in resonant powers in a different manner. When- limits imposed by the shape and size of the in-
fact, make another brief excursion into the realm ever a string or group of strings are struck, the strument itself. The sound-board cannot indeed
of acoustics.
board is thrown into a state of vibration which be longer or wider than the outside dimensions
affects only itself and not the strings that re- of the instrument, and it is necessary that these
The Phenomena of Resonance.
latter be kept within the limits of convenience
The property which the sound-board possesses main damped. The result of this excitement is and portability. But it is a strange fact that
to
expose
a
relatively
great
vibrating
surface
to
of reinforcing and emphasizing the sounds gen-
designers have appeared, generally, to neglect the
erated by the strings is called "resonance." the atmosphere with the immediate consequence obvious alternative. They have, in fact, quite
Important as thi£ property of sonorous bodies that the quantity of air impelled into a state of
ignored the possibility of increasing the cubical
is to musicians and the makers of mu- periodic motion is multiplied many times. Thus content of the sound-board by adding to its thick-
sical instruments, the fact remains that it is the size of the impelled layers of air and the re- ness. It is doubtless true that to provide a
a matter very little understood by the mass of sultant sonorous waves is augmented until we board of great thickness out of one piece of
them. This is the more remarkable when one obtain sounds of the intensity and richness lumber presents an almost impracticable prob-
considers that, without resonant properties, no which we are accustomed to associate with the lem; and it is equally incontestable that such a
board would possess very poor resonant quali-
musical instruments would be possible. For it is pianoforte.
Now, from what we have already learned of the ties. But there is at hand a very simple means
not difficult to perceive that music, as we know it,
could not exist were the means of expressing it laws of tone-quality, it is obvious that the re- of overcoming this difficulty. It lies in the direc-
limited to the actual and immediate bodies that sonant medium must be capable of reinforcing tion of a compromise. Let us take two sound-
perform the motions which are the direct causes not only the fundamental but the partials of all boards and join them together so that the grain
of musical sounds. This fact is most clearly the tones which it influences. To this end we of the wood in each runs in an opposite direction
illustrated in the case of the pianoforte. The must provide a substance that combines elasticity to that of the other. Let us at the same time so
unaided sound of a pianoforte string is ridicu- with the freedom of vibration that is, of course, arrange the belly-bridge construction that the
lously feeble; in fact, it is quite inaudible at the essential. It is not possible to employ metal on remote half of the double board is in direct con-
distance of a few feet. Yet we are all familiar account of its excessive stiffness and consequent tact with the bridge, as by a series of sound posts
with the wonderfully harmonious and powerful resistance to the influence of impressed vibra- projected downwards from the under surface of
sounds that the same string will be the means of tions; while on the other hand a wooden body the bridge, and penetrating to the remote surface
will not be sufficiently stiff and rigid unless of the double board. The immediate result is
producing when aided by the sound-board.
Resonance may be denned as the property artificially strengthened. For this reason it is that we gain at once the increase of cubical
which one sonorous body possesses of impressing customary to construct sound-boards of a freely- content that is required and also the extra ten-
its vibrations upon another sonorous body. The vibrating wood (the spruce-fir is generally em- sion and elasticity that had formerly to be sup-
existence of this power may be demonstrated in ployed for this purpose) and to strengthen it "by plied by means of ribbing. Furthermore, such a
a variety of ways. The most simple proofs are fastening to one side bars of hard wood called construction is far stronger. A sound-board
afforded by the pianoforte itself. For example, "ribs." In this manner the requisite stiffness is constructed in this manner is not at all likely to
if we strike any note upon the instrument and imparted to the board, which at the same time split; nor are there any ribs that can become
at the same time gently press down the corre- is sufficiently susceptible to the impressed vibra- loose, to the impairment of tonal efficiency.
sponding key one octave higher, so as to tions from the strings.
Such a suggestion is by no means revolution-
Usual Construction Obsolete.
raise the damper without at the same time
ary. It has been put into successful practice by
According to the accepted style of construc- at least one maker in Germany and two or more
raising the hammer, we shall find that if
the first key be released while the other tion, the sound-board is composed of a thin sur- in the United States. Undoubtedly it embodies a
is held open, tthe string corresponding to face of spruce, which is backed with a series of
more correct idea than does the generally ac-
the latter will continue to sound its proper hard wood ribs glued across one side of it. Such cepted but obsolete form that is merely the over-
note. In this case the vibrations excited in the a method, has, however, serious disadvantages. grown offspring of the resonance-table in use a
first string travel along the belly-bridge until It is a legacy, in fact, from the days of the century before the birth of a piano-forte.
they reach the nearest open string whose vibra- harpsichord and spinet, and we may find a strik-
(To be continued.)
THE PROBLEM OF PIANO SCALE DESIGN.