Tuning Duplex

[Clark]

> As to your inference that the duplex was developed as a marketing 
> ploy a deeply grieved . That you are suggesting that Hermann 
> Helmholtz, the greatest physicist of the world, in his time, and 
> CFT Steinway the greatest inventor of piano design features 
> collaborated in a marketing ploy belittles our profession, and is 
> not worthy of your dedication to our profession. It is also an 
> insult to the scale designers of countless other pianos who have
> integrated this feature into their instruments. May I suggest you 
> rethink this point of view.


126,848	

UNITED STATES PATENT OFFICE
________________________________________

C.F. THEODOR STEINWAY, OF NEW YORK, N.Y., ASSIGNOR TO HIMSELF,
ALBERT STEINWAY, AND WILLIAM STEINWAY,

IMPROVEMENT IN DUPLEX AGRAFFE SCALES FOR PIANO-FORTES.
________________________________________

Specification forming part of Letters Patent No. 126,848, dated May 14,
1872.

To all whom it may concern:

Be it know that I, C.F. THEODOR STEINWAY, of the city, county, and State
of New York, have invented a new and Improved Duplex Agraffe Scale for
Piano-Fortes; and I do hereby declare the following to be a full, clear,
and exact description thereof, which will enable those skilled in the
art to make and use the same, reference being had to the accompanying
drawing forming part of this specification, which drawing represents a
plan of a grand piano-forte with my improved scale.

My invention consists in bringing the vibrations of that portion of the
string which is situated between the agraffe and the tuning-pin, in
proportion to those of the main portion of the string, in such a manner
that the tone produced by said agraffe section is brought in harmony
with that of the main section, and thereby the purity and fullness of
the tone of the instrument is materially increased; also, in bringing
the longitudinal vibrations of that portion of the string which is
situated between the sounding-board bridge and the hitch-pin in
proportion to the vibrations of the main section of the string, so that
the sounds due to these longitudinal vibrations are brought in harmony
with the tone of the main section of the string, and the purity and
fullness of the tone of the instrument is improved

In order to enable others to understand my invention, I will here remark
that the term "scale" of a piano-forte comprises the position of the
strings side by side or above each other, their length and thickness and
their tension; and my improvement is applicable to all stringed
instruments in which the sounds are produced by the action of hammers.

If the bass tones of a stringed hammer instrument are sounded from
octave to octave toward the treble a great difference appears in the
effect of the various strings, according to their length, as far as the
partial tones of the strings are concerned, which are due to the
spontaneous subdivisions of said strings in halves, quarters, eighths,
sixteenths, &c. The longest duration of the vibrations and the highest
quality to subdivide in partial tones is found in the strings between
the contra C and the small c. Within these limits, each string
subdivides itself by the blows of the hammer and by the transverse
vibrations due to the same in a large number of "nodes," whereby the
so-called harmonic overtones are produced, and whereby the fundamental
tone is rendered rich and brilliant. At the same time this portion of
the strings, particularly, produces, by the longitudinal vibration, a
number of unharmonic side tones, making a whistling souind, which
disturbs the purity of the tone. Both these qualities disappear as the
height of the tone increases, so that the limit of producing a pure
fundamental tone is found at a4, while it is in most cases desirable to
obtain a clear tone from c5; but the inherent firmness of the thick
strings generally employed, and the great tension required on account of
the thickness prevents the string of the above named c5 to make the
proper transverse vibrations due to the fundamental tone, and a division
into partial tones is out of the question. In order to effect or promote
the subdivision of the string and to produce the desired partial tones,
I combine with that portion of the string which is situated between the
tuning-pin _a_ (see drawing [not included here]) and the main agraffe
_b_ a secondary agraffe, _e_, which supports the string and is placed at
a distance from the main agraffe corresponding to one of the above-named
subdivisions of the main section _d_ of the string - that is to say, at
a distance equal to 1/2, 1/4, 1/8, 1/16, 1/32, or 1/64 of the length of
the main section, or to any combination of these fractions, The main
agraffe _b_, which supports the string only at one point, allows the
transverse vibrations to extend to that part of the string between the
said agraffe and the tuning-pin,  the vibration of this part being in a
direction opposite to that of the main section of the string. By
inserting the second agraffe c at a distance from the main agraffe equal
to 1/2, 1/4, 1/8, 1/16, 1/32, or 1/64 of the length of the main section
of the string, the subdivision of the string into partial vibrations,
and the consequent production of harmonic overtones is effected or
promoted, and a clear, strong, and brilliant tone is obtained up to the
highest note

In the drawing I have marked opposite to each tuning-pin the proportion
existing between the distance of the two agraffes and the length of the
main section of the string. By allowing the vibration of the string to
extend beyond the main agraffe the durability of the string is
materially increased, since by cutting off the vibration of the string
at this point, as at present uniformly practised, the cohesion of the
metal is disturbed; and it is a fact that nine-tenths of all strings
which break in a piano-forte do so from this cause under the action of
the hammer. By adding my second period of vibration the freedom of the
motion of the string is promoted, and the danger that the same will
break is materially decreased. The unharmonic tones, or the whistling
sounds due to the longitudinal vibrations of the strings, I avoid by
supporting that portion of the string between the sounding-board bridge
and the hitch-pin at distances from the outer bridge-pins equal to 1/2,
1/4, 1/8, 1/16, 1/32, or 1/64 of the length of the main portion of each
string, or to any combination of these fractions. By the sounding-board
bridge the continuation of the transverse vibrations must necessarily be
interrupted, owing to the width of the bridge supporting the string,
whereby  these vibrations are effectually stopped; but particularly with
strings of great thickness, as generally used in piano-fortes of recent
construction, the longitudinal vibrations of the strings extend to those
portions which are situated between the bridge and the hitch-pins; and
in order to avoid unharmonic tones due to these longitudinal vibrations
I apply between the bridge and the hitch-pin _g_, under each strings, a
support, _e_, at a distance from the outer bridge-pin _f_, corresponding
to 1/2, 1/4, 1/8, 1/16, 1/32, or 1/64 of the length of the main section
_d_ of the string, or to any combination of these fractions.

In the drawing I have marked opposite to each hitch-pin the proportion
existing between the distance from the support _e_ to the bridge-pin and
the length of the main section of the string. By these means the
unharmonic tones due to the longitudinal vibrations of the strings are
converted into harmonious tones, which being transmitted through the
bridge to the sounding-board reach the ear and strengthen and enrich the
fundamental tone of the string, instead of disturbing the purity
thereof, as heretofore. The supports _c_ and _e_ may be made of metal,
ivory, or any other material capable of resisting the pressure of the
string.

What I claim as new, and desire to secure by Letters Patent, is -

1. The arrangement, in a piano-forte, of a series of successive strings,
in each of which the vibrations of that portion situated between the
agraffe and tuning-pin are brought in harmony with the vibrations of the
main section of the string, substantially as described.

2. The arrangement, in a piano-forte, of a succession of strings, in
each of which the longitudinal vibrations of that portion of the string
situated between the extreme edge of the sounding-board bridge and the
hitch-pin are brought in harmony with the vibrations of the main section
of the string, substantially as described.

C.F. THEODOR STEINWAY.

Witnesses:
W. HAUFF
R.F. KASTENHUBER.