Improvements relating to the Determination of the Position of Vessels in Foggy Weather.
Year: 1898

page_text: Date of Application, 1st Sept., 1898
Complete Innsification Loft 11th Jan 1900' Aated 2nd June 1800'
Date of Application, 1st Sept., 1898
Complete Specification Loft, 14th Jan, 1900' Accepted 2nd June 1800
Improvements relating to the Determination of the Position of
Vessels in Foggy Weather.
I, EMILE LACOINE, of Passage du Tunnel à Pera, Constantinople, in the
Empire of Turkey, Government Electrician, do hereby declare the uature of this
invention to be as follows:-
This invention relates to a method for preventing accidents, during foggy or
misty weather, due to ignorance of the exact position of the ship which is being
steered, on approaching coasts, at the entrance to channels, in the vicinity of n
reef or of another vessel.
In order to attain this object, I place at the points forming the entrance to
channels, or in positions equidistant from these points; appliances termed "phono-
phores" such as whistles syrens bells and the like which are capable of emitting.
either simultaneously or at definite intervals, sonorous signals of different notes or
characters. In addition to this the application of my method necessitates the
use of special marine charts which, in combination with the signals of the phono-
phores, enable the direction in which the vessel is travelling and the distance
which separates it from the phonophores to be estimated.
The installation of phonophores enables the four following problems to be
readily solved.
1. The entrance to an entirely open channel.
2. The entrance to a channel in which there are obstacles and the determination
of the direction.
3. Determination of distances.
4. Determination of the position of a vessel.
.
1. The entrance to an entirely open channel may be effected by means of signals
simultaneously emitted from two fixed points signalling the entrance to a channel:
For this purpose I arrange at these two points known appliances capable of pro-
ducing intensely sonorous signals, of different natures, such for example as a
syren at one point and a whistle at the other. The two points are connected by
means of a submarine cable, which serves to establish electrical connections
between them and to cause the sounds of the syren and of the whistle
to be omitted at precisely the same time. These two appliances, which may be
operated by means of compressed air and of a motor of any suitable kind for
example, are so. arranged as to emit such sounds simultaneously and at regular
intervals, of one minute for instance.
Assuming that a vessel situated to the left of the median line is desired to
enter the channel along the said median line, upon this vessel will be heard each
minute first of all the sound of the syren, then shortly afterwards the sound of
the whistle, it will then at once he known that the vessel is to larboard' of the
said median line. The vessel will then be manoeuvred until the whistle and the
syren are heard simultaneously, when it will be upon the said line. The vessel
will then be steered in such a manner as to keep it upon this line by noting in

page_text: what order the sounds of the syren and of the whistle are heard if the median
line should not be strictly adhered to.
If it is impossible to connect the phonophores by means of a cable in such a
manner as to render their signals simultaneous, it is agreed that one of the signals
shall emit its sound each minute and that the other signal shall repeat it
immediately the sound reaches this station. The interval between the sound of
the whistle and that of the syren being thus determined and indicated upon the
marine charts, it will be known that a vessel is upon the median line if the two
gounds are lieard with the normal interval. If the sounds are heard closer
together or further apart, it will in the same way be known that the vessel is to
larboard or to starboard of the line.
2. The entrance to a channel with an obstacle to be avoided is effected in a
similar manner by means of two phonophores emitting either simultaneous or
successive sounds. The direction of the vessel may be determined by the use of
marine charts drawn as follows:
Upon a chart indicating the channel, from two points as centres I draw con-
centric circumferences numbered from 1 to 10 at intervals of 300 metres, the
approximate rate of travel of sound through the air. The points of intersection
of these circumferences determines a series of hyperbolas 1b 2b 3b
1 2 3. . .
.
Upon a vessel upon the line 2b will be heard the sounds emitted from the syren
two seconds before the sounds emitted simultaneously from the whistle. In the
same way if upon a vessel situated on the opposite side of the line sounds from
the syren are heard two seconds after those from the whistle, it will be known that
the vessel is upon the line 2. If upon the line 4 for example, there is situated
an obstacle the vessel will of course be caused to avoid this direction.
In cases in which the signals are not simultaneous but successive, the deter-
mination of the direction may be effected as readily, as before since the interval
between the emissions of the signals is known and is given by the special charts.
3. Determination of distances. The position of the vessel upon one of the
homofocal hyperbolas.drawn upon the charts may be completely determined if the
distance from the vessel to one of the points is known. For this purpose it is only
necessary that the vessel should be provided with a sonorous signal and by means
of question and reply which is by agreement to be immediate, the time required
for sound to traverse the distance separating the vessel and the signal and back
again may be ascertained upon the vessel!
If there is no. signal sufficiently powerful upon the boat, the distance to the
phonophore may be ascertained by the following method, which is based upon
the difference of the speeds of sound in air and in water.
The phonophore is provided for this purpose with two signals, one of which is
acrial and the other submarine, both of them acting simultaneously. The vessel
is provided with a suitable annunciator immersed in the water, which serves to
collect the sounds. It is then only necessary to note upon the vessel, by means
of a chronometer, the interval. of time which has elapsed between the reception
of the sound transmitted through the water and the reception of the aerial sound;
the product of this interval measured in seconds multiplied by 375 gives approxi-
mately the distance in metres between the vessel and the double signál.
4. Determination of the exact position of a vessel-The exact position of a
vessel may also be ascertained by means of three phonophores and of a double
system of hyperbolas traced upon the chart. The three phonophores are provided 5
at one point with a whistle, at another point with a syren and at a third point
with a bell. Upon the special chart are marked hyperbolas having for focii on
the one hand the points of the syren and whistle. and on the other the points of
the whistle and bell. According to the order of succession of the sounds emitted
simultaneously by the three phonophores, it will be known upon what lines the 5
vessel is situated with respect to these two systems, and its exact position will
consequently be known at the intersection of these lines.

page_text: The methods indicated above are adapted for use on vessels in the open sea;
which if provided with phonophores may mutually inform each other as to the
distance separating them and their route by the aid of conventional signals. In
the vicinity of plionopliores situated upon a coast, vessels may ascertain their
respective distances and certainly avoid collision.
reserve the right to establish in any suitable manner the installations_neces-.
sary to the emission and to the perception of the sounds, comprising on the one
hand motors suitable mechanisms and connections assisting in the production of
the sonorous signals and to their simultanity and on the other hand the receiving
and registering devices for these signals.
I also reserve the right to establish marine charts in accordance with my inven-
tion upon which are traced homofocal hyperbolas enabling the exact position of
vessels in foggy or misty weather to be ascertained when employed in combination
with the "phonophores."
Improvements relating to the Determination of the Position of
Vessels in Foggy Weather.
I, EMILE LACOINE, of Passage du Tunnel A à Pera, Constantinople, in the
Empire of Turkey, Government Electrician, 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:—
This invention relates to a method of and apparatus for the prevention of acci-
dents at sen uuring the prevalence of fog, owing to ignorance of the position of
the vessel in approaching the shore, at the entrance to straits, in the neighbourhood
of a lighthouse which is invisible, of a reef or of another vessel in movement.
With this object I arrange at the points at which the entrance to straits is
signalled, or at positions equidistant from such points, appliances which I term
phonophores," and which are capable of emitting simultaneously sonorous
signals, of different nole or nature, this installation necessitating the employment
of a cable electrically connecting these two points and permitting of acting upon
mechanism adapted to insure such simultaneous action, this mechanism may, for
example, be operated by means of compressed air produced by a motor of any.
suitable kind.
Aphonophore" denotes any convenient type of apparatus for producing a
powerful sound, and it may be either a whistle, siren, bell or the like of any
known construction. As will be hereinafter explained' two such apparatue, one
at each signalling station at the entrance to a harbour or the like, are caused to
act in unison by connecting them with an electric cable, but the sound produced
by each must be of a different nature to that of its fellow apparatus. Thus one
apparatus inay produce the sound of a whistle and the other that of a siren, or
the first apparatus may give the sound of a bell in E (mi) and the second one that
of C (do).
•
The application of my method necessitates, in addition, the use of special
marine charts, drawn upon novel principles, which, in conjunction with the
phonophores, enable the direction taken by the vessel and the distance. which
separates it from the phonophores to be determined.
The accompanying drawings relate to the method of drawing, and to the various

page_text: use of the special charts employed with my system, in combination with the
appliances which simultaneously emit sonorous signals.
Figure 1 and 2 relate to the case of a vessel entering a passage which is
entirely unobstructed.
Figures 3 and 4 relate to the drawing of hyperbolic and homofocal curves
enabling the direction of the vessel to be determined, for cases where two phono-
phores connected one with the other or isolated one from the other, are employed
and where an obstacle is situated in the passage.
Figure 5 relates to an arrangement enabling the exact position of a vessel to
be located.
I would here remark that the object of this description is principally to set
forth my novel method, and to protect certain improvements in the drawing of
marine charts.
The arrangement according to my invention of phonophores emitting sonorous
signals in conjunction with the use of the marine charts which I have devised for
this purpose, enable the four following problems to be solved in a simple manner.
1. The entrance into a strait or passage which is entirely unobstructed.
2. The entrance into the same in the presence of obstacles and determination
of the direction followed.
3: Determination of distances;
4. Determination of the position of a vessel.
1. The entrance into a strait or passage which is entirely unobstructed, may be
accomplished by means of signals emitted simultaneously from two fixed points b
and t, signalling the entrance to the passage.
For this purpose at b and t, which may be lighthouses for example, I install
known appliances capable of producing signals which are sonorous and intense but
of different natures. Thus & may produce the note "do" and the note "mi," notes
which are readily distinguishable by the car, but it is preferable to arrange a
siren at band a whistle at t as these are sounds which cannot possibly be
confounded:.
เ
I connect the points band t by means of a submarine cable, which not only
enables communication to be established between the two points, which would be
desirable in any case, but also enables the engines to be installed in such a
manner that they may be acted upon electrically, and the notes of the siren and
whistle to be emitted at exactly the same time.
I am of course aware that for a long time past sonorous signals have been
employed in time of fog, but these signals are only at the most capable of
signalling the approach of dauger without indicating the distance or even the
direction in spite of attempts which have been made in this direction.
The installations at the points and are made in such a manner that they are
capable of emitting simultaneous sounds at regular intervals, for example a sharp
short sound every minute.
The points 6 and which are provided with these sonorous appliances may be
termed "phonophores."
Assuming that it is desired to bring a vessel at a into the passage band t
along the median line dd Figure 1, upon such vessel will at first be heard each
minute the sound of the siron 6, then, a little afterwards, the sound of the
whistle, t. It will at once be understood that the vessel is situated to port of
the line d, and it will be steered to starboard so as to approach this line. This
course will be continued until the sound of both. siren and whistle are heard
simultaneously; the vessel will then be situated upon the line dd.
་
A special marine chart for the strait will give the angle of dd with the
meridian. It will then be known what course to mark upon the marine compass
in order to remain upon the line dd. If however, this line should be departed
from, the navigator will be warned of this each minute; because as long as the
vessel remains upon the line dd, he should hear the two sounds, at the same
time, otherwise he knows that he has deviated from his course. If, for example,

page_text: the vessel has moved to the positions a¹ he will first of all hear the whistle and
then the siren and will know that he should rectify his course by going to port.
The greater the interval separating the two sounds, the more the vessel will be
to port or to starboard, according as the siren or the whistle is first heard: With-
out knowing the distance which separates the vessel from the entrance of the
strait bt, it will be known from the increase of sound that it is being approached.
Likewise if the vessel passes the line bt the fact will be notified by the diminution
of the sounds.
!
In the above method it is assumed that it is possible to connect the two phono-
plores band by means of a submarine cable enabling simultaneous signals to be
produced. If, however, the vessel' is entering a strait which is only signalled out
at sea by means of two lightships provided with phonophores, experience proves
that it is very difficult to connect these two movable points by means of a sub-
marine cable, which would be rendered useless in a very short time. In such a
case the following plan may be adopted:
The two floating signal-ships, and t, being provided with phonophoric appli-
ances, the time in seconds which is required for a sound coming from t to reach b
is first of all determined by experiment; for greater clearness we will assume that
the time required is 8 seconds. In this case, there is no necessity that the sounds
should be of different natures, they may both be sirens or both whistles; but
even in such a case it is preferable that they should be of different natures, as
above stated. Each minute, for example, the phonophore will emit a sound
which will be repeated by the phonophore b, immediately the sound coming from
it is heard; 8 seconds after in the present case. If a vessel is situated upon the
line d d the two sounds will be heard one after the other, with eight seconds
interval. If the vessel occupies the position a, it will be situated at an equal
distance from band from t. When the whistle sounds at t, the sound will be
heard at a after a certain number of seconds, according to the position of the
vessel upon the line d; this number we will call n. The sound from will take
ciglit seconds to reach b, then the signal at b will act immediately and will
taken seconds to reach a since ba = ta. The sound from b will thus be
heard 8+ n seconds after that from t and the interval between the two sounds as
received at a will be 8 + 12 - 72= 8 seconds.
In this case the vessel sliould be provided with a seconds counter, or better still.
with a pocket recording chronograph of a known kind.
When the sound of the whistle is heard upon the vessel, that is to say the sound
coming from t, the knob of the chronograph is pressed; and when the sound of the
siren coming from 6 is subsequently heard, the knob is again pressed and the
difference between the recorded marks will indicate the time which has elapsed
between the two sounds.
If this difference is 8 seconds, the vessel is upon the line dd. If the vessol is
at a a', for example, the difference with be less than 8 seconds. If the difference
exceeds 8 seconds the vessel will be to starboard, at a" for example. The vessel
should thus be steered in such a manner that an interval of 8 seconds invariably
exists between the times at which the two sounds are audible; if this rule is
observed the vessel can be brought into the strait as readily and certainly. as. in
the preceding case where the sounds are simultaneous.
2. Entrance to a strait when an obstacle has to be avoided is effected in a
similar manner, either by means of two phonophores electrically connected and
emitting simultaneous signals, or by means of isolated phonophores emitting their
signals in succession:
The direction followed by the vessel may be determined at any moment by the
use of special marine charts, drawn in the following manner:
Upon a chart (Figure 3) indicating the strait, starting from the point t and the
point b. I trace concentric circles at intervals of 300 metres; corresponding to the
approximate speed of sound in the atmosphere.
These two series of circles, numbered from 1 to 10, intersect.

page_text: The circles 44, 5-5 . . . . 9-9 10-10, intersect at the middle, that is
to say upon the line dd, whilst the circle 3b intersects with the circle.5 at 3.5 of
the port side. In tlie same manner the circle 4 intersects with 6 at 4.6 port,
and so forth. These points being united, form the line 2 port, upon which is first
heard the siren, then two seconds afterwards the whistle. The lines b
3h
7b; 8b, are determined in the same manner.
By symmetry and by the same reasoning, the lines 1', 2*
determined.
.
7t and 8t are
A vessel at a, would be to port upon the line 2b, whilst at a' it would be to
Starboard at point 7.5 upon the line 2..
Consequently when the two sounds are heard one after the other, it is known
upon which line the vessel is situated, and consequently the direction which should
be followed to enter the strait without being obliged to follow the line d d. If an
obstacle is situated in the strait, a rock at m for example, upon the direction 4,
the vessel should of course avoid this direction. The special charts will enable
the proper direction to be readily found.
When the two phonophores are not electrically connected, and when an interval
of say 8 seconds, separates the signals, there are traced (Figure 4) concentric circles
from and b, at intervals of 500 metres.
It will thus be understood that, if for example the vessel is at a, the sound of
the phonophore will be heard after 7 seconds since it is situated upon the
circle 7 Upon a vessel similarly situated at a¹, the sound of b will be heard
5 seconds after its emission, since it is situated upon the circle 5b, but the sound
will only reach the vessel 5+8 (that is to say 13) seconds after the emission of the
sound at The difference in the perception of the two sounds will thus be
13-7, 6 seconds, and the vessel will consequently be upon line 6 of the chart. to
port. The lines 0, 1, 2
15 and 16, which are traced upon the chart and
which indicate the direction to be followed in order to enter the strait, are deter-
mined in a similar manner.
If one of them, the line 4 for example, is barred by an obstacle m marked
upon the chart, it will of course be known that the vessel should avoid this
direction.
3. Determination of distances. The position of the vessel upon one of the
hyperbolic homofocal lines described upon the marine charts may be exactly
determined, if the distance separating the vessel from one of the points 6 or
is known this distance may be determined in the first place by the methoil of
question and reply.
We will assume that it is desired to ascertain the distance of the vessel from
the point t. (Figure 1). The point and also the vessel a should be provided
with a phonophoric appliance. The phonophore will emit its signal at regular
intervals. When the signals are heard at a it will be known that the vessel is in
greater or less proximity to t, and if it is desired to ascertain the exact distance the
operation is as follows:
The vessel a will make the conventional Morse signal with its phono-
phore d) for example, thereby indicating "I wish to know the distance.'
The phonophoret will then give the same signal signifying ""I will give it."
The vessel a will then emit a short sound and at the same time its chronograph
is adjusted. The sound reaches t, where the operators are prepared and immedi-
ately reply with a similar short sound.
This sound will reach the vessel a and immediately it is heard the chronograph
is again adjusted; the captain will consequently be able to read the number of
seconds which has elapsed between the emission of his signal and that coming
from t, say 12 seconds, for example. The sound will have occupied one half. this
time, that is to say 6 seconds, in coming from a lot, and the distance required
will be 6 x 390-1800 metres.
This distance may likewise be ascertained by means of a double signal in air
and water.

page_text: In order to carry out the method explained above it is necessary that the signals
emitted at regular intervals by the phonophore t should be suspended during the
question and reply as to distance and also that the vessel' a should likewise be pro-
vided with a phonophore, which latter may be of but small power, seeing that sail-
ing vessels would possess no means of operating by steam. Under these condi-
tions a vessel could only carry out the operation at reduced distances.
When possible the following method of operation is preferable; the vessel a has
no need of a phonophore or of questioning the station . Its distance may be
determined without the intervention of t, and in addition to this several vessels
may independently determine their distance from the point t, either by operating
at the same time or one after the other.
As is well known the velocity of sound is greater in water than in air; now in
water, experiments have shown that this velocity slightly exceeds 1500 metres per
second. This we call 1500 metres in order to facilitate the explanation which
follows.
A double phonophoric appliance is installed at which is capable of producing
at regular intervals two simultaneous signals, one in water by striking upon a hell
immersed at a predetermined depth, and the other in air by means of a siren or
whistle.
The important point is that the sounds should be emitted at the same time by
the mechanism.
In Figure 1 lett be a phonophore installed in this manner and a a vessel. The
vessel need only be provided with a chronograph and a suitable annunciating
instrument immersed in water and serving to collect the sounds.
If at any moment the phonophore emits the two sounds, which are subsequently
heard upon the vessel a, the sound coming through the water is first heard and the
chronograph set, and then the sound coming through the air becomes audible and
the chronograph is again adjusted. A very simple calculation will shew that the
number of seconds representing the difference between the perception of the two
sounds, multiplied by 375, gives the distance of the vessel in metres. The ratios
of the velocities of sound in air and in water, may vary according to the density.
of the sea; this difference may be calculated in advance by consulting suitable
tables.
The exact position of a vessel upon one of the hyperbolic homofocal lines, may
also be found without its being necessary to determine its distance from one of
the points b, t. In this case the operation is as follows: Instead of providing only
two phonophores b, producing sounds in the manner above stated, and which
serve to determine the lines of direction, a third may be employed when possible.
The phonophoret, for example, is provided with a whistle, with a siren, and
the third e with a bell suspended in the air (Figure 5).
Upon the special chart are marked the lines of direction with respect to the
points band, as above described; these being traced in full lines. From the
points and c are traced in the same manner, in similar directions, dotted lines.
These lines meet in pairs, and if, for example, by the emission of sounds from b
and t, it is known that the vessel is upon the full line 2b, and that subsequently
by the emission of sounds from b and c it is found that the vessel is upon the
dotted line 2t it will also be known that the vessel is upon the point of inter-
section of these two lines that is to say at a.
Finally the position may be determined by means of two stations b and t. ascer-
taining the distance of the vessel from these two points by means of one of the
methods above described.
These calculations are facilitated by means of concentric circles described
around b. and t..
OBSERVATIONS. The methods above described for determining distance may be.
employed by a vessel approaching or leaving a point provided with a phonophore;
because it can readily be perceived whether the vessel is approaching or leaving
the point in question.

page_text: This is necessary in order to avoid a lighthouse or a reef provided with such
apparatus, in time of fog.
By this means also fishing boats may find their vessel in time of fog.
So far it has been assumed that the vessel has not moved during the operations
necessary for determining its position or direction.
Generally during the prevalence of fog speed is reduced, but even if the vessel
maintains a speed of 10 knots an hour, for example, it only amounts to about
5 metres per second, which is very little as compared with the velocity of sound
through the air.
Assuming that the operation has required 8 seconds, the vessel will not have
proceeded for a greater distance than 40 metres, which is a negligible quantity:
The approximation of the position may be considered sufficient since the error
in the case cited, would be less than the length of an ordinary vessel. In
addition to this, it should be remarked that, as a general rule, less than 8 seconds
will be required. In practice, therefore, the vessel may almost always be con-
sidered as motionless..
Upon the high seas, two vessels provided with phonophores could ascertain their
distance ou approaching each other; they may also, by means of conventional
signals, communicate thier respective courses. They are thus provided with the
means for diminishing and even for avoiding the danger of collision.
The process which I have indicated for ascertaining distance by means of sounds
in air and water, may be applied in other cases, by utilizing the velocity of sound
in air, in water, in metallic bodies and in the earth; for example by means of
wires rails pipes and so forth.
If several vessels are entering a strait together, they may do so in safety after
having come to an agreement either by signal or in advance. One will enter.
upon the line 6b, another upon dd, another upon 3, and so on. If one vessel
is leaving and the other entering, they may agree upon the courses to follow by
means of signals, and will thus certainly avoid a collision. They might of course
follow predetermined hyperbolic lines as a result of a general understanding.
Generally speaking, if vessels are in proximity to phonophores, as they are liable
to determine their respective distances, a collision can always be avoided.
Having thus described the principle of my invention I reserve the right to
establish in any appropriate manner, the installations necessary for the emission
and perception of the sounds, comprising on the one hand the motors, mechanism
and connections employed in the production of sonorous signals and for causing
them to be simultaneous, and, on the other hand, the devices for receiving and
recording these signals.
The marine charts in accordance with my invention, upon which are described
the homofocal hyperbolic directing lines, employed in combination with phono-
phores, will enable the exact position of a vessel to be determined in case of fog
as above stated, a result which has never hitherto been attained.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. An installation for the application of a method of determining distances
between a vessel and certain fixed points on shore in case of fog or obscurity of
any kind, by means of the measurement of the intervals of time elapsing between
the reception of various sonorous signals emitted at known intervals of time, this
installation comprising in principle appliances provided with sonorous signals.
such as whistles, sirens, bells and the like. so arranged as to produce sounds.at
predetermined intervals, at two or more fixed points on shore, in combination with
known appliances enabling the intervals of time elapsing between the perception
of the sonorous sounds to be recorded, such as chronographs or the like installed
upon the vessel.
2. In an installation for the application of a method in accordance. with

page_text: Claim 1, the combination of a fixed station comprising a whistle or equivalent
device emitting sounds at regular and known intervals of time, with a second
fixed station provided with a siren or other equivalent appliance, different from
the appliance provided at the first station, these two appliances being connected!
by any suitable known means for causing the second appliance to act either simul-
taneously with or at a predetermined interval after the emission of the first
sound, in combination with a recording apparatus such as a chronograph provided
upon the vessel, the whole for the purpose above specified
:
3. In an installation for the application of a methods in accordance with Claim 1,
the combination of three fixed stations capable of emitting, either simultaneously
or at known intervals of time, different signals, such as a siren; a whistle and a
bell, for example, and of a registering device, such as a chronograph, provided
upon the vessel, the whole for the purpose above described:
4. In an installation for the application of a method in accordance with Claim I;-
the combination of two or three fixed stations, emitting different sonorous aërial
signals, at known intervals of time, with an apparatus emitting sonorous signals
in water, arranged at one of the fixed stations and operating at the same time as
the aerial sonorous signal of the same station, and with known receiving and
recording appliances, provided upon the vessel and enabling the intervals of time
separating the perception of the different sounds transmitted through air and
water to be determined, the whole for the purpose above specified.
5. In an installation for the application of the method in accordance with
Claim 1, marine charts, prepared for the approaches to coasts, passages straits and
the like, upon which are described a series of homofocal, hyperbolic curves, and
intended to be employed in conjunction with the installations comprising two
stations provided with sonorous signals in accordance with Claims 1, 2, 4, for the
purpose of determining the course which the vessel is following and its exact
position with reference to reefs, entrances to sounds, and other points marked
upon the charts, substantially as above described!
6. In an installation for the application of the method in accordance withi
Claim 1, marine charts prepared for the approaches to coasts, straits, sounds and
the like, upon which are described two series of homofocal, hyperbolic curves and
intended to be employed in conjunction with the installations comprising three
stations. provided with sonorous signals in accordance with Claims 1, 2 and 4,
in order to determine the course which the vessel is following and its exact posi-
tion with respect to reefs, entrances to sounds, and other points marked upon the
charts, substantially as above described.
Dadadi k 1441 1.
די
1000
:
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, WC., Agents for the Applicant.