AN IMPROVED METHOD OF AND TOPOPHONE OR APPARATUS FOR DETERMINING THE DIRECTION, RELATIVELY TO THE PLACE OF OBSERVATION, OF A SOUND-PRODUCING INSTRUMENTALITY, APPLICABLE MORE ESPECIALLY TO THE NAVIGATION OF A VESSEL IN A FOG
Year: 1880

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "AN IMPROVED
METHOD OF AND TOPOPHONE OR APPARATUS FOR DETERMINING THE DIRECTION,
RELATIVELY TO THE PLACE OF OBSERVATION, OF A SOUND-PRODUCING
INSTRUMENTALITY, APPLICABLE MORE ESPECIALLY TO THE NAVIGATION OF
A VESSEL IN A FOG." A communication from abroad by Alfred Marshall
Mayer, of South Orange, in the County of Essex, State of New Jersey, United
States of America.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 4th February 1880.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "AN IMPROVED METHOD OF AND TOPOPHONE OR
APPARATUS FOR DETERMINING THE DIRECTION, RELATIVELY TO THE PLACE OF
OBSERVATION, OF A SOUND-PRODUCING INSTRUMENTALITY, APPLICABLE MORE
ESPECIALLY TO THE NAVIGATION OF A VESSEL IN A FOG." [A communication
from abroad by Alfred Marshall Mayer, of South Orange, in the County of Essex,
State of New Jersey, United States of America.]
These improvements relate to a method of and apparatus for determining the
direction, relatively to the point of observation, of a sound producing instrumentality,
and hence by a series of observations, conducted at two or more different points
upon the same base line, affording the data necessary for determining the distance
of the sound producing instrumentality from the place of observation; and the
Invention consists, broadly, in the application to the same sound-wave surface of
two resonators tuned to the pitch of the sound under observation, and fixed at a
distance from each other somewhat less than the length of the wave of such sound,
and connected by means of tubes to a single pipe, to which the tubes conduct the
sound vibrations collected by the resonators, and by which such vibrations are
conducted to the ear of the observer whereby when the connecting or confluent
tubes are alike in length, the sound so collected from the same wave surface and
conducted to the ear of the observer is augmented in intensity; or, on the other
hand, when the connecting tubes are relatively varied in length, the sound 80
collected and conducted to the ear of the observer is diminished in intensity by

page_text: reason of the greater or less degree of interference of the sound vibrations, such
inteference being greatest when the relative difference in the lengths of the
connecting tubes amounts to or includes a length equal to one half the wave length
of the sound. As such augmentation or diminution in the intensity of the sound is
only manifested when the mouths of both resonators touch, or nearly touch, the
same sound wave surface, and as the sound wave surface is substantially a sphere
at the centre of which the sound is produced, it follows that when both resonators
touch the same sound wave surface, a line drawn from the mouth of one resonator
to the mouth of the other is a chord of the sphere, and that a line perpendicular
thereto is a radius of the sphere, or, in other words, coincides in alignment with a
line drawn from the place where the sound is produced through the place of
observation. By moving a measured distance laterally at an observed angle
from the radius line thus found a second radius line may in like manner be
found.
The distance between the two points of observation is the base line of a triangle
of which the two convergent radius lines are the sides. The length of this base
line and the observed angles therewith of the two radius lines constitute sufficient
data for the computation by familiar processes of the length of the two sides of the
triangle, or the distance of their point of junction, and hence the distance of the
sound producing instrumentality from the place of observation. The apparatus for
this purpose is called the topophone, and the Invention incidentally includes means
of adjusting the two resonators at variable distances from each other; means of
varying the lengths of one or both of the connecting tubes; a suitable frame for
the support of the various parts of the apparatus, affording an axis of oscillation
which is substantially perpendicular to a line drawn from one resonator to the
other, and a pointer which is substantially perpendicular to the axis of oscillation
and to a line drawn from one resonator to the other.
This Invention may be employed either upon land or water, but its principal
object is to facilitate the safe navigation of a vessel in a fog. In the latter case a
base line is obtainable by sailing the vessel an observed distance in a straight line
from one point of observation to the other.
The topophone may either be permanently erected upon a vessel or other
structure, or it may be made in portable form. In the former case the apparatus is
supported on a T shaped frame, composed substantially of a shaft to one end of
which a cross bar is centrally attached.
Two resonators are each supported transversely upon the cross bar by means of a
sliding connection, so that they may be respectively adjusted equidistantly from the
shaft and at variable distances from each other.
The resonators are (of the usual telescopic construction, and are tuned in the
ordinary manner by sliding in and out the telescopic joints or by varying the area
of their mouths.
The shaft has attached to it a handle and a pointer, the latter arranged to move
over a divided circle, which in some cases may be connected with or form a part of
a mariner's compass. Sound vibrations received in the mouth of the two resonators
are conducted through preferably flexible confluent tubes connected to a single pipe,
one or both of these conducting tubes being made adjustable in length by being
provided with a telescopic joint, by which it is made capable of being lengthened or
shortened. The opposite end of the single pipe is also branched, and two flexible
ear tubes are connected respectively with the branches for the purpose of conducting
the vibrations simultaneously to both ears of the listener or observer.
When the apparatus is constructed in portable form the shaft is dispensed with,
and the bar upon which the resonators are supported is adapted to fit the shoulders,
back, or some other part of the person of the observer, and the pointer or index is
carried by a frame secured to the said bar, which extends in front of the median
line on the face of the observer to serve as an index to the direction of the
sound.
b
In using the topophone the resonators are first tuned to the pitch of the sound

page_text: to be observed. This is effected by sliding the telescopic joints of the resonators in
or out in the usual manner, until the normal pitch of the resonator corresponds to
the pitch of the sound to be observed. The resonators are then adjusted equidis-
tantly from the central shaft at a distance from each other slightly less then the
wave length of the sound to be observed.
When the apparatus is to be used to augment the intensity of the sound under
observation, the telescopic joint of the longitudinally adjustable conducting tube
is adjusted until the said tube is of equal length with the other conducting tube,
or until the length of the adjustable tube does not differ from the length of the
other tube by any fractional part of a wave length of the sound under observation.
The shaft being then held in an upright position is slowly rotated upon its
longitudinal axis until the mouths of both resonators touch the same sound-wave
surface.
The observer, having the ends of the ear tubes applied to his ears, will perceive
a sudden augmentation in the intensity of the sound when the mouths of both
resonators touch or nearly touch the sound-wave surface. The position of the
pointer then coincides in alignment with a line drawn from the source of sound
through the place of observation.
For the purpose of verifying the result thus obtained the mode of observation
may be changed by sliding together the telescopic joint of the adjustable conducting
tube until said tube is diminished in length to an amount equal to half the wave
length of the sound under observation. Then upon rotating the apparatus as
before at the instant when the months of the resonators touch, or nearly touch, the
same sound-wave surface, there will be a diminution in the intensity of the sound
heard by the observer, owing to a greater or less interference of the sound waves
in the pipe. At the instant when this diminution in the intensity of the sound is
observed the pointer will also coincide in alignment with a line drawn from the
sound producing instrumentality through the place of observation.
It will of course be understood that either form of observation may be repeated
with the resonators adjusted at variable distances from each other.
If desired, several pairs of resonators may be arranged upon the same frame, one
pair above the other, but ordinarily I prefer one pair only.
I do not limit myself to the exact form of constructing the apparatus described,
as the Invention may be embodied in various forms, and is present in any structure
in which a pair of resonators provided with ear tubes are supported in a position
substantially parallel to each other, so that their mouths can be conveniently
applied to the same sound-wave surface, and a line drawn from the mouth of one
resonator to the other will be susceptible of observation as a chord of the sound-
sphere. Nor do I limit myself to any particular kind of resonators or sound
receivers, as in carrying out my Invention I may employ resonators or resonant
cavities, or ear trumpets, or tubes, or boxes, or any other vibrants or sound receivers
capable of acquiring by application to the sound wave surface like phases of vibration
therewith, and reflecting or transmitting such vibrations through confluent tubes
to a single pipe or chamber wherein the vibrations may conspire if the confluent
tubes are of equal length, or interfere if the confluent tubes are of unequal length,
and thus, as the case may be, either augment or diminish the intensity of the
sound transmitted from the pipe to the ear of the observer at the instant when the
two sound receivers simultaneously touch the same sound wave surface.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the 4th
August 1880.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "AN IMPROVED METHOD OF AND TOPOPHONE OR
APPARATUS FOR DETERMINING THE DIRECTION, RELATIVELY TO THE PLACE OF
OBSERVATION, OF ▲ SOUND-PRODUCING INSTRUMENTALITY, APPLICABLE MORE
ESPECIALLY TO THE NAVIGATION OF A VESSEL IN A FOG." A communication
from abroad by Alfred Marshall Mayer, of South Orange, in the County of Essex,
State of New Jersey, United States of America.
These improvements relate to a method of and apparatus for determining the
direction, relatively to the point of observation, of a sound-producing instru-
mentality, and hence by a series of observations, conducted at two or more different
points upon the same base line, affording the data necessary for determining the
distance of the sound-producing instrumentality from the place of observation;
and the Invention consists, broadly, in the application to the same sound wave
surface of two resonators or sound receivers tuned to the pitch of the sound under
observation, and fixed at a distance from each other somewhat less than the length
of the wave of such sound, and connected by means of tubes to a single pipe to
which the tubes conduct the sound vibrations collected by the resonators, and by
which such vibrations are conducted to the ear of the observer, whereby when the
connecting or confluent tubes are alike in length, the sound so collected from the
same wave surface and conducted to the ear of the observer is augmented in
intensity; or on the other hand when the connecting tubes are relatively varied in
length, the sound so collected and conducted to the ear of the observer is diminished
in intensity by reason of the greater or less degree of interference of the sound
vibrations, such interference being greatest when the relative difference in the
lengths of the connecting tubes amounts to or includes a length equal to one half
the wave length of the sound. As such augmentation or diminution in the
intensity of the sound is only manifested when the mouths of both resonators
touch or nearly touch the same sound-wave surface, and as the sound wave surface
is substantially a sphere at the centre of which the sound is produced, it follows
that when both resonators touch the same sound-wave surface, a line drawn from
the mouth of one resonator to the mouth of the other is a chord of the sphere, and
that a line perpendicular thereto is a radius of the sphere, or, in other words,
coincides in alignment with a line drawn from the place where the sound is pro-
duced through the place of observation. By moving a measured distance laterally
at an observed angle from the radius line thus found, a second radius line may in
like manner be found. The distance between the two points of observation is the
base line of a triangle of which the two convergent radius lines are the sides. The
length of this base line and the observed angles therewith of the two radius lines
constitute sufficient data for the computation by familiar processes of the length
of the two sides of the triangle, or the distance of their point of junction, and
hence the distance of the sound-producing instrumentality from the place of
observation.
I call this apparatus the topophone, and the Invention incidentally includes
means of adjusting the two resonators at variable distances from each other; means
of varying the lengths of one or both of the connecting tubes; a suitable frame for
the support of the various parts of the apparatus, affording an axis of oscillation
which is substantially perpendicular to a line drawn from one resonator to the
other, and a pointer which is substantially perpendicular to the axis of oscillation
and to a line drawn from one resonator to the other.
This Invention may be employed either upon land or water, but its principle
object is to facilitate the safe navigation of a vessel in a fog. In the latter case a

page_text: base line is obtainable by sailing the vessel an observed distance in a straight line
from one point of observation to the other. The topophone may either be
permanently erected upon a vessel or other structure or it may be made in portable
form, as will be seen on reference to the accompanying Drawings, in which
Figure 1 is a side elevation showing the manner of erecting the topophone upon a
vessel or other structure; Figure 2 is a perspective view of a portable topophone;
Figure 3 is a central longitudinal section of one of the resonators; and Figure 4 is
a representation in detail of the lower end of the spindle which constitutes the axis
of oscillation for the apparatus.
Similar letters of reference indicate corresponding parts. The apparatus consists
of a T shaped frame, composed substantially of the shaft S to one end of which
the cross bar R is centrally attached. Two resonators A and B are each supported
transversely upon the bar R by means of a sliding connection, so that they may
be respectively adjusted equidistantly from the shaft S and at variable distances
from each other. The resonators are of the usual telescopic construction, and are
tuned in the ordinary manner by sliding in and out the telescopic joints, or by
varying the area of their mouths. The shaft S has attached to it a handle N and
a pointer P, the latter arranged to move over a divided circle, which in some cases
may be connected with or form a part of a mariners' compass. Sound vibrations
received in the mouth of the resonator A are conducted through the preferably
flexible tube D to one of the branches M of the pipe I. The opposite branch H of
the tube I receives vibrations collected by the resonator B through the longitudinally
adjustable tube E, E', provided with the telescopic joints F and G, by which it is
made capable of being lengthened or shortened by sliding the tube G in or out of
the tube F. The opposite end of the pipe I is also branched, and two flexible
tubes L and K are connected respectively with the branches a and b for the
purpose of conducting the vibrations simultaneously to both ears of the listener or
observer. When the apparatus is constructed in portable form the bar upon which
the resonators are supported is adapted to fit the shoulders, back, or some other
part of the person of the observer, as illustrated in Figure 2, on reference to which
it will be seen that the pointer or index O is secured to the bar R¹, and extends
in front of the median line on the face of the observer to serve as an index to the
direction of the sound.
In using the topophone the resonators are first tuned to the pitch of the sound
to be observed. This is effected by sliding the telescopic joints of the resonators in
or out in the usual manner until the normal pitch of the resonator corresponds to
the pitch of the sound to be observed. The resonators are then adjusted equi-
distantly from the shaft S, at a distance from each other slightly less than the
wave length of the sound to be observed. When the apparatus is to be used to
augment the intensity of the sound under observation, the telescopic joint of the
conducting tube E, E, is adjusted until the tube E, E, is of equal length with the
tube D or until the length of the adjustable tube E, E¹, does not differ from
the length of the tube D by any fractional part of the wave length of the sound
under observation. The shaft S being then held in an upright position is slowly
rotated upon its longitudinal axis until the mouths of both resonators touch the
same sound-wave surface. The observer having the ends of the tubes L and K
applied to his ears will perceive a sudden augmentation in the intensity of the
sound when the mouths of both resonators touch or nearly touch the sound-wave
surface. The position of the pointer then coincides in alignment with a line drawn
from the source of sound through the place of observation.
For the purpose of verifying the result thus obtained the mode of observation
may be changed by sliding together the telescopic tubes F and G until the conducting
tube E, E, is diminished in length to an amount equal to half the wave length of
the sound under observation. Then upon rotating the apparatus, as before, at the
instant when the mouths of the resonators touch or nearly touch the same sound-
wave surface, there will be a diminution in the intensity of the sound heard by the
observer owing to a greater or less interference of the sound waves in the pipe I.

page_text: At the instant when this diminution in the intensity of the sound is observed the
pointer will also coincide in alignment with a line drawn from the sound producing
instrumentality through the place of observation.
It will of course be understood that either form of observation may be repeated
with the resonators adjusted at variable distances from each other. If desired
several pairs of resonators may be arranged upon the same frame, one pair above
the other, but ordinarily I prefer one pair only. I do not limit myself to the exact
form of constructing the apparatus shown in the Drawings, as the Invention may
be embodied in various forms, and is present in any structure in which a pair of
resonators provided with ear tubes are supported in a position substantially parallel
to each other, so that their mouths can be conveniently applied to the same sound-
wave surface, and a line drawn from the mouth of one resonator to the other will
be susceptible of observation as a chord of the sound-sphere. Nor do I limit myself
to any particular kind of resonators or sound receivers, as in carrying out the
Invention I may employ resonators or resonant cavities or ear trumpets, or tubes,
or boxes, or any other vibrants or sound receivers capable of acquiring by application
to the sound-wave surface like phases of vibration therewith, and reflecting or
transmitting such vibrations through confluent tubes to a single pipe or chamber
wherein the vibrations may conspire if the confluent tubes are of equal length, or
interfere if the confluent tubes are of unequal length, and thus, as the case may be,
either augment or diminish the intensity of the sound transmitted from the pipe to
the ear of the observer at the instant when the two sound-receivers simultaneously
touch the same sound-wave surface.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is,-
1st. The combination with each other of two resonators or sound receivers
respectively provided with ear tubes and mounted upon a suitable support, with
their mouths substantially the same in plane, substantially as and for the purpose
set forth.
2nd. The combination with each other of two suitably supported ear-tubed
resonators or sound receivers, substantially such as described, with means of
adjusting the resonators or sound receivers at variable distances from each other,
substantially as and for the purpose set forth.
3rd. The combination of two suitably supported resonators or sound receivers
provided with confluent tubes with a single pipe, to which the tubes respectively
conduct the vibrations collected by the resonators or sound receivers, and from
which such vibrations are conducted to the ear of the observer, substantially as
described.
4th. The combination of two resonators or sound receivers and a single pipe with
conducting or confluent tubes connecting the resonators or sound receivers with
the pipe, one or both of which conducting tubes is longitudinally adjustable,
substantially as and for the purposes set forth.
5th. The combination of two ear-tubed resonators or sound receivers with a
supporting frame provided with a pointer erected thereon in a line perpendicular
to a line drawn from one resonator or sound receiver to the other, substantially as
and for the purpose set forth.
6th. The combination of two resonators or sound receivers with a supporting
frame provided with a shaft or axis for facilitating the oscillation of the resonators
or sound receivers upon a common centre of motion.
7th. In combination with the two resonators or sound receivers provided with
confluent tubes, the adjustable tube E, E¹, composed of the two sections G and F
sliding one upon the other, substantially as described.
8th. The combination in an instrument for determining the direction of sounds
of the resonators or sound receivers A, B, the confluent tubes D and E, E¹, the
supporting bar R, and the shaft or axis S, substantially as and for the purpose set
forth.

page_text: 9th. The method herein described of determining the direction relatively to the
place of observation of a sound-producing instrumentality, by rotating two ear-
tubed resonators or sound receivers about a common axis, and observing their
position when both resonators are brought at the same time into position upon the
wave surface of the sound, or bear that relation in position to the position of the
wave surface in which they perceptibly augment or diminish, as the case may be,
the intensity of the sound transmitted to the ear of the observer.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Third day of August, in the year of our Lord
One thousand eight hundred and eighty..
A. M: CLARK. (L.S.)