An Improved Instrument for Localising or Ascertaining the Direction of Origin of Sounds.
Year: 1889

page_text: Date of Application, 13th Aug., 1889
Complete Specification Left, εth May, 1890-Accepted, 28th June, 1890
PROVISIONAL SPECIFICATION.
An Improved Instrument for Localising or Ascertaining the
Direction of Origin of Sounds.
I, CHARLES DE GOYON, DUC DE FELTRE, of 59, Rue St. Dominique, Paris, France,
hereby declare the nature of this invention to be as follows:-
My Invention relates to a phonogenograph or instrument whereby the direction of
origin of a sound, e.g. that of a fog horn or siren may be quickly and accurately
determined.
My Invention, which is based on the property of the paraboloid, is illustrated in the
accompanying drawing forming part of this specification wherein figure 1 is a central
vertical section of the instrument and figure 2 is a diagram illustrating the path of
the sound waves in the instrument. The same letters of reference indicate the same
parts in both figures.
P is a truncated parabolic reflector terminated towards the vertex in the focal
plane A B. Conjoined with, but apparently directed to, the reflector P is a second
parabolic reflector having the same focus F, the two reflectors being in open com-
munication at the focal plane. The function of this second reflector is to again render
parallel the direction of the waves of sound which after entering the reflector P
parallel to its axis are caused to converge to, and cross at, the focus F, the waves being
finally received in a mouth piece to which the ear may be applied directly or
through the medium of a flexible tube. The instrument is rotateable about a vertical
axis, but instead of being mounted on a foot it may be suspended from above. To
prevent the wind, by entering the parabolic reflector P, from impeding the observation
a diaphragm M is introduced between the parabolic reflector R and the mouth
piece C. This membrane does not in any way interfere with the precision of the
observations. It has been found that a sound emitted at a great distance is clearly
heard in the instrument when the axis of the paraboloid coincides in direction with
the source of the sound, and that not only is the sound more audible by the aid of the
instrument than by the unaided ear but that when the instrument is directed away
from the source of sound the latter is no longer audible.
In using the instrument, the observer listens at the car piece whilst the instrument
is rotated in azimuth until it coincides in direction with the sound which is easily
recognised by the intensification of the sound as compared with that perceived by the
unaided ear and as compared with its inaudibleness when the instrument is turned in
another direction. The possible errors of observation have been found not to exceed
eight degrees and may therefore be neglected for the purposes to which the instrument
is applied.
To this instrument may be applied tell-tales to indicate at various parts of a ship
the point of the compass to which the instrument is directed, and recording apparatus
may also be combined with the instrument for preserving a graphic record of the
working of the instrument.
CHAS. DE GOYON, DUC DE FELTRE.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.

page_text: COMPLETE SPECIFICATION.
An Improved Instrument for Localising or Ascertaining the
Direction of Origin of Sounds.
1, CHARLES DE GOYON, DUO DE FELTRE, of 59, Rue St. Dominique, Paris, France,
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:
My Invention relates to a phonogenograph or instrument whereby the direction of
origin of a sound, c.g. that of a fog horn or siren may be quickly and accurately
determined.
My Invention, which is based on the property of the paraboloid, is illustrated in the
drawing accompanying my Provisional Specification, wherein figure 1 is a central
vertical section of the instrument, and figure 2 is a diagram illustrating the path of
the sound-waves in the instrument. The same letters of reference indicate the same
parts in both figures.
The instrument comprises a truncated parabolic reflector P terminated towards the
vertex in the focal plane A B. It further comprises a second parabolic reflector R
conjoined with, but oppositely directed to, the reflector P the two reflectors R and P
having a common focus F and being in open communication with each other at the
focal plane. The function of this second reflector is to again render parallel the
direction of the waves of sound which on entering the reflector P parallel to its axis
have been caused to converge to, and cross at, the focus F. The sound waves after
being thus again parallelised are finally collected in a receiving cone C to which the
ear of the observer may be applied directly or through the medium of a flexible tube.
The whole instrument is rotatable about a vertical axis, but, instead of being mounted
on a foot, as shewn, it may be suspended from above.
To prevent the wind, by entering the parabolic reflector P, from impeding the
observation, a light membrane or diaphragm M is introduced between the para-
bolic reflector R and the receiving cone C. This membrane does not in any way
interfere with the clearness and precision of the observations.
It has been found that a sound emitted at a great distance is clearly heard in the
instrument when the axis of the paraboloid coincides in direction with the source of
the sound, and that not only is the sound more audible by the aid of the instrument
than by the unaided ear but that when the instrument is directed away from the
source of sound the latter is no longer audible.
In using the instrument to ascertain the true direction of origin of a sound which
may have been first perceived by the unaided ear, the observer listens at the receiving
cone C or at the ear piece connected thereto whilst the instrument is rotated about its
vertical axis so as to scan the horizon in all directions, until the acoustic axis of the
instrument coincides in direction with the source of origin which is easily recognised
by the apparent intensification of the sound as compared with that perceived by the
unaided ear, and as compared with its inaudibleness when the instrument is turned in
another direction. The possible errors of observation have been found not to exceed
eight degrees and may therefore be neglected for the purposes to which the instrument
is applied.
The rotation of the instrument about its vertical axis may be effected by any suitable
means and through the medium of any suitable mechanical arrangement which it is
obvious may vary considerably according to the circumstances under which the
instrument is installed, but, for the sake of precision of the operation it is preferable
that the instrument should be rotated by the person by whom it is used for making the
acoustic observations.
With the employment of this instrument may be combined that of tell-tales to
indicate at various parts of a ship, the point of the compass to which the instru-
ment is directed, and recording apparatus may also be combined with the instrument
for preserving a graphic record of the use of the instrument.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is;
The herein described phonogenograph or instrument for use in localising or ascer-
taining the direction of origin of sounds, the operation of the said instrument being
based on the properties of the paraboloid applied to act substantially in the manner
herein specified.
Dated this 8th day of May 1890.
CHARLES DE GOYON, DUC DE FELTRE.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.