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TECHNICAL^SUPPLY DEPARTMENT
William Braid White, Technical Editor
The Fundamental Scientific Principles
Which Are Behind the Hammer in Piano
Cristofori Did a Pretty Complete Job in the Original Piano With the Problem of the Hammer
and Thus Little Attempt Was Made for Years to Study the Meeting of the Hammer and
Wire—Some of the Problems Confronting Makers of Hammers of Present Day
HOSE who from time to time feel them-
selves tending towards a certain impa-
tience at the leisurely pace of the transi-
tion from ancient to modern methods in piano
making should pause long enough to consider
the case of the hammer. It was with the inven-
tion and application of this device that Cristo-
fori entered that new path of tone production
along which the whole long way of the piano-
forte industry has traveled during two hundred
years. His first care evidently was to perfect
the shape and the material of this device, for we
find, as between the sketch made by Maffei in
1711 and the 1720 and 1726 instruments happily
preserved to us, an enormous mechanical differ-
ence. It is plain that the pioneer and inventor
had in the interval thought out the details of the
percussion problem to a remarkable degree of
accurate conclusion. During the ten years of
experiment which elapsed between his disclo-
sures to Maffei (1709) and the construction of
the instrument now in the Metropolitan Mu-
seum of New York Cristofori traveled a long
way. He learned to graduate the sizes of the
hammers from bass to treble. He learned to
shape them ovalwise in the bass, and to graduate
them also to more and more sharply pointed
outlines as he went up in the scale. He learned,
too, though this is beyond our immediate con-
cern, to mount them on pivoted stems and to
connect them with the keys by means of a mech-
anism of which the principles have not yet been
surpassed. And he undoubtedly experimented
with various sorts of coverings, ultimately
settling upon the leather which for a hundred
years held its own against all competition.
In a word, Cristofori did a pretty complete
job on his hammers, and it is therefore not so
astonishing as it otherwise might be to learn
that his successors made very little attempt for
many years to investigate scientifically the prob-
lems surrounding the meeting of hammer and
wire. Nor, in fact, need we be astonished if
we find that hammer making is still a matter
of experiment, trial and error, with the methods
now in use mainly based upon the results of
many such rough processes. That hammers are
so very good and do so well what they are
designed to do only shows, of course, that ex-
periment is the basis of all mechanical achieve-
ment.
What Are "Scientific Methods"?
On the other hand . . . and this is some-
thing that a certain type of mind can not or will
not see . . . it is precisely upon experiment
that, all scientific "theories," so called, are based.
It is the belief of most so-called "practical"
men (meaning by that men who, in the words
of a great scientific experimenter, "feel them-
selves at liberty to practice only the errors of
their predecessors") that scientific "theories"
are dreams adumbrated by gentlemen sitting
apart and remote from the world in university
classrooms, or roaming amidst academic shades.
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In fact, of course, scientific "theories" are the
painful result of many experiments repeated
over and over again with an excess of precau-
tion against errors of judgment and an excess
of accurate measurement and determination of
quantity which would drive a practical man
crazy, until results have been obtained, checked,
rechecked and verified to a point from which
an explanation of them can be found to cover
all the facts. The findings are then submitted
to the judgment of the scientific world, and only
after they have been repeatedly confirmed by
independent workers are they likely to be
adopted by the general consent of scientific men
as the basis of a full-fledged "theory." Until
that time comes they remain at best the basis of
a "working hypothesis," which is to be thrown
aside the moment some contradictory fact bobs
up. Huxley once said, with his usual good-
natured sarcasm, that the solemn humorless
Herbert Spencer's only notion of a tragedy was
a theory killed by a fact. That little quip gives
a sidelight on what I mean.
Now the point of this digression is that, if
the processes and methods of scientific inquiry
had early been devoted to musical instruments,
and especially to that most fascinating of all
such instruments, the pianoforte, we should by
this time know much more than we do know
jfbout tone production, we should by now be able
much better to control it and to produce some-
thing supremely good, both in quantity and in
quality. And in the case of such scientific work
ever having been done (which unhappily is only
an assumption without basis) we may be sure
that attention would have been centered upon
(1) the wire, (2) the hammer, and (3) the sound
board. These elements would have been sub-
jected to analysis, their physical functions have
been ascertained and working hypotheses have
been framed concerning the obscure problems
of their behavior when working interdepend-
ently. In this way gradually there would have
been built up an accumulation of evidence upon
which might have been erected rules for design
and construction far surpassing anything at
which by ruder methods we have hitherto been
able to arrive.
Nothing like this, in fact, as we know, did or
could happen. Actually things took their own
William Braid White
Associate, American Society of Mechanical
Engineers; Chairman, Wood Industries
Division, A. S. M. E.; Member, American
Physical Society; Member, National Piano
Technicians' Association.
Consulting Engineer to
the Piano Industry
Tonally and Mechanically Correct Scales
Tonal and Technical Surveys of Product
Tonal Betterment Work In Factories
References to manufacturers of unquestioned
position In Industry
For particulars, address
209 South State Street, CHICAGO
35
course and piano construction went on its way.
What we have learned about the behavior of
the hammer in its contact with the string, and
of the string in its contact with the hammer
has been very little. Scientific statement on
the subject, based upon scientific investigation
under controlled conditions, can hardly be said
to have existed in any form available to the gen-
eral technical public, until the publication of
Ortmann's epoch-making book two years ago.
To-day, because of what that book contained,
and what it expressed, there is more disposition
on the part of piano technicians to speak freely
and to impart for general good more of their
own persona] knowledge. In a word, the epoch
of scientific investigation is apparently at hand,
at least so far as concerns the string, hammer
and sound board of the pianoforte.
The Known Facts
Among these, the hammer remains always
fascinating and mysterious. We can put our
knowledge of its influence upon tone into the
following sentences:
1. When a string is struck it breaks up into
segmental vibrations after its whole length
vibration has been evoked. This segmentation
arises from the reflection of the energy from
one end to the other of the string, and the
consequent crossing of impulses and setting up
of stationary waves.
2. The quality or color of the sound emitted
by a struck string depends upon the wave form,
which is another way of saying that it depends
upon how many of the segmental vibrations
into which the motion of the string becomes
subdivided have sufficient amplitude to be au-
dible. Since the amplitude in each case must
vary inversely with the length of the vibrating
segment, the smaller segments vibrating with
lesser amplitude, it follows that a strong stroke
upon a string brings out more of the audible
results of segmental vibrations (audible partial
tones) and therefore of the quality of the sound,
corresponding to the complex of these, what-
ever this may be. In other words, the quality
of the sound is partly dependent upon the power
of the stroke delivered by the finger on the
key. Every change in hammer velocity (loud-
ness) corresponds to a parallel change in quality.
3. The wave form taken up by a string also
depends upon the nature of the material with
which it is struck and upon the shape of the
striking surface. Generally speaking, it may
be taken for granted that, when struck with a
hard, sharply pointed hammer, as, for instance,
a very light and short sharp-pointed steel bar
set into a handle, a pianoforte string will de-
velop at least eight well-defined and audible seg-
mental vibrations, corresponding (with one ex-
ception) to the elements of the major chord of
the fundamental. The exception is the seventh
partial, which is dissonant. Moreover, there will
probably be higher partials developed, depend-
ing upon the length and the stiffness of the
string, and these will be dissonant, of course.
4. It is also certain that when such a string
is struck by such a hammer as described in
paragraph three, directly upon one of its nodal
points, the partial tones (segmental vibrations)
originating at that node will be blotted out.
It follows, therefore, that the partial tone suc-
cession which appears as the result of setting
(Continued on page 36)
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