Improvements in Electro-mechanical Devices for Producing Cor- responding Positions in Transmitting and Receiving Apparatus.
Year: 1897

page_text: Improvements in Electro-mechanical Devices for Producing Cor-
responding Positions in Transmitting and Receiving Apparatus.
We, ARCHIBALD BARR, Professor of Engineering in the University of Glasgow,
and WILLIAM STROUD, Professor of Physics in the Yorkshire College, Leeds, do
hereby declare the nature of this invention to be as follows:-
Our invention consists in an improved system of telegraphy by means of which
communication can be easily and rapidly made between different stations for
the conveyance of information etc. such as is required on board war-vessels and
other ships for the communication of orders, messages, angular observations in
altitude or azimuth, ranges, helm or engine signals and for many other similar
purposes on land such as e.g. the communication of military orders in fortresses or
the automatic transmission of information as regards the level of water in a distant
reservoir and many other purposes.
The apparatus consists of a transmitting instrument and one or more receiving
instruments. These we may refer to as the "transmitter" and 66 recorder
respectively. The former may be operated in accordance with the message to
be sent, either by hand (as for example when orders are to be transmitted) or
automatically when the motions of some independent mechanism; are to be
indicated, as e.g. when information regarding the position of a ship's helm is to
be communicated to the bridge or when the height of water in a reservoir is to
be communicated to the waterworks office or when the azimuthal or range indica-
tions of a rangefinder are to be transmitted to a gun or battery.
In some cases the receiving instrument or recorder consists of a wheel-work
mechanism provided with a spring, weight, electro-motor or other driving agency,
and an escapement mechanism controlled by means of intermitted currents
communicated from the transmitting instrument, which wheel-work is connected
mechanically to a pointer moving on a dial or other indicating surface bearing a
scale, printed messages orders or other indications, or to an automatic recording
device by means of which a record is made of the transmitted indications on a
revolving drum or otherwise, or the apparatus may be arranged both to indicate
temporarily and to record permanently the messages transmitted.
One of the principal features of our invention is the provision of means whereby
in such transmitting and recording apparatus the rate of motion of the trans-
mitting and recording mechanisms shall be independent of the rate of motion of
the actuating mechanism of the transmitter so that however the actuating
mechanism may be operated the transmitting and recording mechanisms shall
when started operate at a predetermined speed.
Suppose the instrument is to be arranged so as to send any succession of orders
or scale readings printed or indicated on the margin of a disc at the transmitting
station as e.g. when the transmitter is placed in the conning tower of a battleship
and the recorders are in the ship's batteries,

page_text: A handle operating an index pointer may be arranged to move around the dial
as is customary in ship's telegraphs of other constructions. The operation of
this handle moves an electric contact ring or its equivalent having an insulated
part or space say opposite the aforesaid pointer. A brush is caused to move in
connection with the movements of the apparatus which sends the intermitte l
electrical currents before referred to and when the brush is upon the contact ring
it completes an electric circuit which releases a detent mechanism, enabling the
intermitter to operate so as to send intermitted currents to the recorder, and at the
same time to move the brush over the contact ring. When however the brush
arrives at the insulation, or gap, in the contact ring, the detent is applied to the
intermitter stopping at the same time the motion of the brush and the motion of
the pointer of the recorder.
In some cases, instead of operating the brush directly from the mechanism of
the intermitting device, we may use the intermitted currents sent by the inter-
mitter to operate the brush in a manner similar to that in which the indicating
hand of the recorder is operated. Thus, when the handle is moved one or more
steps forward the contact ring is brought under the brush, the detent of the
intermitting mechanism is released, and the brush and the hands of the recorders
are caused to move forward one or more steps in conformity with the particular
movement given to the handle.
The intermitting mechanism may conveniently consist of a revolving fly or
centrifugal governor upon the spindle of which there is a projecting contact piece,
which, coming into contact with a stationary brush for a portion of each revolu-
tion completes the electric circuit with the recorder.
In some cases we may use more than one contact piece and in some cases more
than one brush e.g. when the transmitter is so arranged as to work by means of
currents of opposite signs or when currents are to be sent from one intermitter
to several electro-magnets at the recorder.
The escapement gear of the recorder may consist of an escapement wheel more
or less similar to the escapement wheel of a clock together with a vibrating escape-
ment lever caused to move, in one direction, by the attraction of an electro magnet
actuated by the intermitted currents sent from the transmitter and in the other
direction, by a spring, gravity control, or its equivalent.
In some cases it is advisable that the recorder pointer should be capable of being
operated either forward or backward in conformity with forward or backward
movements of the transmitter handle. In such cases we may provide upon the
recorder two escapement mechanisms and correspondingly two intermitting
mechanisms at the transmitter which intermitters are connected by separate
circuits to the two escapement gears respectively. The escapement gears may
then be so arranged that when one of them is operated the pointer moves forward,
when the other is operated the pointer moves backward, the connection from the
two spindles of the two escapement wheels to the spindle of the recorder hand
being conveniently made through the system of three bevel wheels known as a
differential gear.
The two intermitter spindles at the transmitter when these are to operate the
brush by mechanical connection may similarly be connected to the spindle of the
brush through a differential gear. In this case instead of the contact ring with
one gap referred to above we may provide two half rings insulated from each other
and electrically connected respectively to the detent gears of the two intermitters.
In this manner the apparatus may be arranged so that when the transmitting
handle is moved forwards and therefore the brush brought into contact with one
of the half rings the detent of one of the intermitters (which we may call the
forward intermitter) is released and an intermitted current is sent to the forward
escapement gear of the recorder so that the brush on the transmitter and the
pointer of the recorder both move forward through corresponding distances;
and again if the transmitter handle is moved backwards the backward intermitter
is released and correspondingly the brush and the recorder pointer move backwards.

page_text: In such cases it will be evident that instead of using two intermitters we may
accomplish a like result by having one intermitter and a switch arrangement
which causes the intermitted current to pass to the forward or to the backward
escapement gear of the recorder according as the backward or forward half ring
is brought into contact with the brush. In this case the action of the intermitter
may be communicated to the brush through the medium of a reversing mechanism
operated so that though the intermitter moves in one direction only the brush
may move forwards or backwards according as the brush is in contact with the
forward or backward haff ring, or again, the brush may be operated by mechanism
having an escapement gear controlled by the intermitted current in the same
manner as described for the recorder.
When it is important to have as few wires as possible connecting transmitter
and recorder, as for example when the distance between the instruments is great,
and still to operate the recorder backwards and forwards, we may arrange that
the intermitting mechanism sends positive or negative currents to the recorder
in accordance with the forward or backward motion of the handle of the trans-
mitter and provide two polarised electro-magnets in the recorder the one being
actuated by intermitted positive currents and being unaffected by intermitted
negative currents and the other being operated when the intermitted currents are
negative but being unaffected by intermitted positive currents.
When the apparatus is to be used to transmit automatically the motion of a
mechanism it will be readily understood that the same general mode of operation
can be adopted. Thus e.g. when the variation in the level of the water in a
reservoir or the movements of a ship's helm are to be transmitted the up and
down, or the to and fro, motions of a mechanism in accordance with the move-
ments to be indicated, take the place of the motion imparted to the handle of
the transmitter and straight or curved contact bars (operated by the movement
to be recorded) may take the place of the contact half rings referred to above, a
brush being given a corresponding movement over these bars by the mechanism
of the transmitter and the motion of the hand of the recorder upon its dial may
be replaced by a corresponding up and down or to and fro motion of a pointer
upon a scale.
Instead of starting the intermitter by means of electric currents in a circuit
completed by the contact of the brush with the contact ring we may sometimes use
an equivalent mechanical device. Such a device may for example be constructed
by substituting for the electrical contact ring a ring having a gap or depression
and for the brush a lever working over such ring in such a manner that when the
lever is upon the main portion of the ring it is raised or depressed and withdraws
the detent allowing the intermitter to start, whereas when the lever reaches the
depression in the ring the detent is applied to stop the intermitter.
Again instead of indicating by means of a pointer upon a scale, or in addition
to indicating by means of a pointer upon a scale, we may cause the recording
mechanism to move a recording pencil on a paper drum or card moved in another
direction in accordance with lapse of time or other variable so that a permanent
record may be obtained of the motions of the transmitting device.
We sometimes operate the two escapement wheels of the recorder by separate
springs or other driving agents and again we sometimes use one driving agent
and a differential gear to communicate driving forces to the two escapements.
Again one spiral driving spring may be used, one of the two escapement gears
being connected to the inner end of the spiral and the other to the outer end, sc
that the spring is able to operate whichever of the escapement wheels is permitted
to move by the oscillations imparted to its lever.
We may provide an indicating arrangement to enable the attendant to observe
when the driving spring of the instrument requires re-winding. This may con-
veniently consist of a dial over which a pointer moves in accordance with the
winding up or running down of the spring and when one spring is used in the

page_text: manner last described the dial may be given a motion in accordance with the
movements of the outer end of the spring while the pointer moves in accordance
with the motions of the inner end of the spring or vice versa.
These motions may
be conveniently communicated from the spring by providing on the spindle of
the disc and pointer respectively toothed wheels, which are moved, one tooth for
each revolution of the respective end of the spring, by means of a projection
acting on the one tooth system commonly adopted in various counting machines.
The transmitting mechanism may conveniently have besides the contact brush
above referred to, a pointer operated in connection therewith so as to show
transmitter that the apparatus has operated as desired by such pointer coming
to the stopping at the indication to which the pointer of the transmitter handle
has been brought by the operator.
on the
It will be evident that we can use the motion imparted to the hand of the
recorder as a transmitting motion to send back to the transmitting station an
indication of the motion of the recorder in the manner described, so that the
operator at the transmitting station may see that the recorder has worked in the
desired manner and has shown the particular indications required.
We sometimes omit the handle and contact ring portions of the transmitting
mechanism, and substitute a switch (or two switches as the case may be) so arranged
that when the switch is pressed the detent of the transmitter is released, and the
pointer moves round the dial in accordance with the motions of the intermitter.
The operator then keeps the switch in action till the pointer reaches the required
indication, when the release of the switch stops the motion by bringing the
detent into operation.
We may also arrange an electric bell to be operated either by the intermitted
current or by the current operating the detent mechanism or by an independent
current, so that the observer at the recorder is warned of a signal being sent or
when the bell works in connection with the intermitted current, he may be able
to judge by hearing what the change of indication is. Two bells differing in tone
may be used in some cases, one operating when the recorder is moving backwards,
the other when it is moving forwards.
The apparatus may be applied to the construction of position finders for military.
purposes, by using two transmitters one at each observing station communicating
with two recorders having arms in place of pointers moving in conformity with
the transmitter motions. The pivots of the two recorder arms being placed
relatively to each other in such positions as to indicate on any chosen scale the
positions of the transmitting stations, the point of meeting (or overlap) of the
two recorder arms will indicate the point of meeting of the arms attached to the
transmitting mechanism, and thus, when the arms of the transmitters are directed
to one distant object (say an enemy's ship when the apparatus is used as a coast
defence position finder) the point of meeting of the arms of the recorders will
indicate the enemy's position on a chart placed under the recorder arms. Again,
the motions of the recorder arms may communicate motion to a third pivoted arm,
the pivot of which represents with relation to the pivots of the recorder arms any
chosen position relatively to the transmitting stations-say the position of a
battery so that the direction taken by the third arm will indicate the direction
of the enemy's position from the battery, while the distance of the point of meeting
of the recorder arms from the pivot of the third arm will indicate the enemy's
range from the battery. Each of these indications may again be transmitted to
the battery by the means herein described.
Or again, the apparatus may be applied to the construction of position finders
by using two transmitters in connection with a rangefinder one of the transmitters
communicating the azimuth of the object as seen from the rangefinder, the other
communicating the range as indicated by the rangefinder.
The recording devices may then be so arranged that a pivoted arm is moved at
the battery or other recording station in accordance with the azimuthal motion
of the rangefinder while a point on this arm is moved to and fro in accordance

page_text: with the range indicated by the rangefinder. The combined movements of this
point may then be caused to move a second pivoted arm, the pivot of which is so
placed relatively to the pivot of the first arm as to indicate on the chosen scale
the position of the battery relative to the rangefinder station. The azimuthal
direction taken by the second arm will thus indicate the azimuth of the distant
object relatively to the battery while the distance of the point of crossing of the
two arms upon the second arm will indicate the range of the object from the
battery. In this manner the apparatus may be used in connection with range-
finders of the single observer type such as those invented by the present applicants
or rangefinders of the depression type sometimes used in connection with coast.
stations.
Improvements in Electro-mechanical Devices for Producing Cor-
responding Positions in Transmitting and Receiving Apparatus.
We, ARCHIBALD BARR, Professor of Engineering in the University of Glasgow,
and WILLIAM STROUD, Professor of Physics in the Yorkshire College, Leeds, 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:-
Our invention consists in an improved system of telegraphy by means of which
communication can be easily and rapidly made between different stations for
the conveyance of information etc. such as is required on board war-vessels and
other ships for the communication of orders, messages, angular observations in
altitude or azimuth, ranges, helm or engine signals and for many other similar
purposes on land such as e.g. the communication of military orders in fortresses or
the automatic transmission of information as regards the level of water in a distant
reservoir and many other purposes.
The apparatus consists of a transmitting instrument and one or more receiving
instruments. These we may refer to as the "transmitter" and recorder
respectively. The former may be operated in accordance with the message to
be sent, either by hand (as for example when orders are to be transmitted) or
to be
automatically when the motions of some independent mechanism are
indicated, as e.g. when information regarding the position of a ship's helm is to
be communicated to the bridge or when the height of water in a reservoir is to
be communicated to the waterworks office or when the azimuthal or range indica-
tions of a rangefinder are to be transmitted to gun or battery.
In some cases the receiving instrument or recorder consists of a wheel-work
mechanism provided with a spring, weight electro-motor or other driving agency,
and an escapement mechanism controlled by means of intermitted currents
communicated from the transmitting instrument, which wheel-work is connected
mechanically to a pointer moving on a dial or other indicating surface bearing a
scale, printed messages orders, or other indications, or to an automatic recording
device by means of which a record is made of the transmitted indications on a
revolving drum or otherwise, or the apparatus may be arranged both to indicate
temporarily and to record permanently the message transmitted.
One of the principal features of our invention is the provision of means whereby

page_text: in such transmitting and recording apparatus the rate of motion of the trans-
mitting and recording mechanisms shall be independent of the rate of motion of
the actuating mechanism of the transmitter so that however the actuating
mechanism may be operated the transmitting and recording mechanisms shall
when started operate at a predetermined speed.
Suppose the instrument is to be arranged so as to send any succession of orders
or scale readings printed or indicated on the margin of a disc at the transmitting
station as e.g. when the transmitter is placed in the conning tower of a battleship
and the recorders are in the ship's batteries.
A handle operating an index pointer may be arranged to move around the dial
as is customary in ship's telegraphs of other constructions. The operation of
this handle moves an electric contact ring or its equivalent having an insulated
part or space say opposite the aforesaid pointer. A brush is caused to move in
connection with the movements of the apparatus which sends the intermitted
electrical currents before referred to and when the brush is upon the contact ring
it completes an electric circuit which releases a detent mechanism, enabling the
intermitter to operate so as to send intermitted currents to the recorder, and at the
same time to nuove the brush over the contact ring. When however the brush
arrives at the insulation, or gap, in the contact ring, the detent is applied to the
intermitter stopping at the same time the motion of the brush and the motion of
the pointer of the recorder.
In some cases, instead of operating the brush directly from the mechanism of
the intermitting device, we may use the intermitted currents sent by the inter-
mitter to operate the brush in a manner similar to that in which the indicating
hand of the recorder is operated. Thus, when the handle is moved one or more
steps forward the contact ring is brought under the brush, the detent of the
intermitting mechanism is released, and the brush and the hands of the recorders
are caused to move forward one or more steps in conformity with the particular
movement given to the handle.
The intermitting mechanism may conveniently consist of a revolving fly or
centrifugal governor upon the spindle of which there is a projecting contact piece,
which, coming into contact with a stationary brush for a portion of each revolu-
tion completes the electric circuit with the recorder.
In some cases we may use more than one contact piece and in some cases more
than one brush e.g. when the transmitter is so arranged as to work by means of
currents of opposite signs or when currents are to be sent from one intermitter
to several electro-magnets at the recorder.
The escapement gear of the recorder may consist of an escapement wheel more
or less similar to the escapement wheel of a clock together with a vibrating escape-
ment lever caused to move, in one direction, by the attraction of an electro magnet
actuated by the intermitted currents sent from the transmitter and in the other
direction, by a spring, gravity control, or its equivalent.
In some cases it is advisable that the recorder pointer should be capable of being
operated either forward or backward in conformity with forward or backward
movements of the transmitter handle. In such cases we may provide upon the
recorder two escapement mechanisms and correspondingly two intermitting
mechanisms at the transmitter which intermitters are connected by separate
circuits to the two escapement gears respectively. The escapement gears may
then be so arranged that when one of them is operated the pointer moves forward,
when the other is operated the pointer moves backward, the connection from the
two spindles of the two escapement wheels to the spindle of the recorder hand
being conveniently made through the system of three bevel wheels known as a
differential gear.
The two intermitter spindles at the transmitter when these are to operate the
brush by mechanical connection may similarly be connected to the spindle of the
brush through a differential gear. In this case instead of the contact ring with

page_text: one gap referred to above we may provide two half rings insulated from each other
and electrically connected respectively to the detent gears of the two intermitters.
In this manner the apparatus may be arranged so that when the transmitting
handle is moved forward and therefore the brush brought into contact with one
of the half rings the detent of one of the intermitters (which we may call the
forward intermitter) is released and an intermitted current is sent to the forward
escapement the bush and the pointer of the recorder both move forward through
corresponding distances; and again if the transmitter handle is moved backwards
the backward intermitter is released and correspondingly the brush and the
recorder pointer move backwards.
In such cases it will be evident that instead of using two intermitters we may
accomplish a like result by having one intermitter and a switch arrangement
which causes the intermitted current to pass to the forward or to the backward
escapement gear of the recorder according as the backward or forward half ring
is brought into contact with the brush. In this case the action of the intermitter
may be communicated to the brush through the medium of a reversing mechanism
operated so that though the intermitter moves in one direction only the brush
may move forwards or backwards according as the brush is in contact with the
forward or backward half ring, or again, the brush may be operated by mechanisnr
having an escapement gear controlled by the intermitted current in the same
manner as described for the recorder.
When it is important to have as few wires as possible connecting transmitter
and recorder, as for example when the distance between the instruments is great,
and still to operate the recorder backwards and forwards, we may arrange that
the intermitting mechanism sends positive or negative currents to the recorder
in accordance with the forward or backward motion of the handle of the trans-
mitter and provide two polarised electro-magnets in the recorder the one being
actuated by intermitted positive currents and being unaffected by intermitted
negative currents and the other being operated when the intermitted currents are
negative but being unaffected by intermitted positive currents.
When the apparatus is to be used to transmit automatically the motion of a
mechanism it will be readily understood that the same general mode of operation
can be adopted. Thus e.g. when the variation in the level of the water in a
reservoir or the movements of a ship's helm are to be transmitted the up and
down, or to and fro motions of a mechanism in accordance with the move-
ments to be indicated, take the place of the motion imparted to the handle of
the transmitter and straight or curved contact bars (operated by the movement
to be recorded) may take the place of the contact half rings referred to above, a
brush being given a corresponding movement over these bars by the mechanism
of the transmitter and the motion of the hand of the recorder upon its dial may
be replaced by a corresponding up and down or to and fro motion of a pointer
upon a scale.
Instead of starting the intermitter by means of electric currents in a circuit
completed by the contact of the brush with the contact ring we may sometimes use
an equivalent mechanical device. Such a device may for example be constructed
by substituting for the electrical contact ring a ring having a gap or depression
and for the brush a lever working over such ring in such a manner that when the
lever is upon the main portion of the ring it is raised or depressed and withdraws
the detent allowing the intermitter to start, whereas when the lever reaches the
depression in the ring the detent is applied to stop the intermitter.
Again instead of indicating by means of a pointer upon a scale, or in addition
to indicating by means of a pointer upon a scale, we may cause the recording
mechanism to move a recording pencil on a paper drum or card moved in another
direction in accordance with lapse of time or other variable so that a permanent
record may be obtained of the motions of the transmitting device.
We sometimes operate the two escapement wheels of the recorder by separate

page_text: springs or other driving agents and again we sometimes use one driving agent
and a differential gear to communicate driving forces to the two escapements.
Again one spiral driving spring may be used, one of the two escapement gears
being connected to the inner end of the spiral and the other to the outer end, so
that the spring is able to operate whichever of the escapement wheels is permitted
to move by the oscillations imparted to its lever.
We may provide an indicating arrangement to enable the attendant to observe
when the driving spring of the instrument requires re-winding. This may con-
veniently consist of a dial over which a pointer moves in accordance with the
winding up or running down of the spring and when one spring is used in the
manner last described the dial may be given a motion in accordance with the
movements of the outer end of the spring while the pointer moves in accordance
with the motions of the inner end of the spring or vice versa. These motions may
be conveniently communicated from the spring by providing on the spindle of
the disc and pointer respectively toothed wheels, which are moved, one tooth for
each revolution of the respective end of the spring, by means of a projection
acting on the one tooth system commonly adopted in various counting machines.
The transmitting mechanism may conveniently have besides the contact brush
above referred to, a pointer operated in connection therewith so as to show on the
transmitter that the apparatus has operated as desired by such pointer coming
to the stopping at the indication to which the pointer of the transmitter handle
has been brought by the operator.
It will be evident that we can use the motion imparted to the hand of the
recorder as a transmitting motion to send back to the transmitting station an
indication of the motion of the recorder in the manner described, so that the
operator at the transmitting station may see that the recorder has worked in the
desired manner and has shown the particular indications required.
We sometimes omit the handle and contact ring portions of the transmitting
mechanism, and substitute a switch (or two switches as the case may be) so arranged
that when the switch is pressed the detent of the transmitter is released, and the
pointer moves round the dial in accordance with the motions of the intermitter.
The operator then keeps the switch in action till the pointer reaches the required
indication, when the release of the switch stops the motion by bringing the
detent into operation.
We may also arrange an electric bell to be operated either by the intermitted.
current or by the current operating the detent mechanism or by an independent
current, so that the observer at the recorder is warned of a signal being sent or
when the bell works in connection with the intermitted current, he may be able
to judge by hearing what the change of indication is. Two bells differing in tone
may be used in some cases, one operating when the recorder is moving backwards,
the other when it is moving forwards.
The apparatus may be applied to the construction of position finders for military
purposes, by using two transmitters one at each observing station communicating
with two recorders having arms in place of pointers moving in conformity with
the transmitter motions. The pivots of the two recorder arms being placed
relatively to each other in such positions as to indicate on any chosen scale the
positions of the transmitting stations, the point of meeting (or overlap) of the
two recorder arms will indicate the point of meeting of the arms attached to the
transmitting mechanism, and thus, when the arms of the transmitters are directed
to one distant object (say an enemy's ship when the apparatus is used as a coast
defence position finder) the point of meeting of the arms of the recorders will
indicate the enemy's position on a chart placed under the recorder arms. Again,
the motions of the recorder arms may communicate motion to a third pivoted arm,
the pivot of which represents with relation to the pivots of the recorder arms any
chosen position relatively to the transmitting stations-say the position of a
battery so that the direction taken by the third arm will indicate the direction
of the enemy's position from the battery, while the distance of the point of meeting

page_text: of the recorder arms from the pivot of the third arm will indicate the enemy's
range from the battery. Each of these indications may again be transmitted to
the battery by the means herein described.
Or again, the apparatus may be applied to the construction of position finders
by using two transmitters in connection with a rangefinder one of the transmitters
communicating the azimuth of the object as seen from the rangefinder, the other
communicating the range as indicated by the rangefinder.
The recorder devices may then be 'so arranged that a pivoted arm is moved at
the battery or other recording station in accordance with the azimuthal motion
of the rangefinder while a point on this arm is moved to and fro in accordance
with the range indicated by the rangefinder. The combined movements of this
point may then be caused to move a second pivoted arm, the pivot of which is so
placed relatively to the pivot of the first arm as to indicate on the chosen scale
the position of the battery relative to the rangefinder station. The azimuthal
direction taken by the second arm will thus indicate the azimuth of the distant
object relatively to the battery while the distance of the point of crossing of the
two arms upon the second arm will indicate the range of the object from the
battery. In this manner the apparatus may be used in connection with range-
finders of the single observer type such as those invented by the present applicants
or rangefinders of the depression type sometimes used in connection with coast
stations.
In order that our invention may be properly understood and readily carried
into effect, we have hereunto appended four explanatory sheets of drawings in the
several figures of which corresponding parts are marked with corresponding
letters of reference.
Figures 1 and 2 represent one form of the transmitting mechanism, Figure 2
being a plan and Figure 1 a development of a part of the apparatus taken through
the axes of the parts M, N, G₂, U₁. M represents a box containing a clock spring
which by means of a wheel J communicates motion to the bevel wheel X¹ and the
governor G. The wheel J¹ is attached to the spring box and is thus actuated by
the outer end of the spring. The wheel J2, on the other hand (which communicates
motion to the bevel wheel X2 and the governor G2,) is attached to the spindle
passing through the spring box and is thus actuated by the inner end of the
spring. These wheels when respectively released therefore move in opposite
directions and thus communicate motions in opposite directions to the bevel
wheels X and X. The function of the governors G¹ and G2 is to regulate the
speed of working of the apparatus. They are represented as being centrifugal
friction governors; the balls when they fly outwards being arranged to rub upon
the inside of the cylindrical boxes within which they are placed. Air flies or
other controlling appliances may be substituted for friction governors.
I is a mechanism consisting conveniently of a drum of insulating material
into which a metal section is fixed which latter serves to complete an electrical
circuit for a portion of each revolution betwen the springs C3 and 02 which are
placed in circuit with a battery B and the corresponding coils U2 in the receiving
instrument to be described below. This mechanism I2, 02, 02 we call the "inter-
mitter." lt will be evident that instead of having the two brushes capable of
being put into electric contact by means of a contact piece as above described
the current may be taken from the battery to the spindle of I2 taken therefrom
intermittently by a single brush C2 coming in contact with a projection from the
spindle.
A pointer P is connected, in the arrangement shown, to the outer case A of
the transmitting apparatus. This outer case is free to revolve upon the fixed
base B so that the pointer P can be brought over any indication upon the dial D
that it may be desired to indicate at the distant station.
The case A carries with it the glass E to which is attached an electric contact
mechanism F, the construction of which is indicated in detail in Figures VII
and VIII, Figure VII being an elevation & Figure VIII an inverted plan.

page_text: This contact mechanism consists in one form of the apparatus of two half rings Fi
and insulated from each other but connected respectively to two complete
rings and K². A brush L attached to the spindle N of the transmitting
mechanism moves over the ring F1, F2 and being connected electrically by means
of a brush with a battery B or other source of electricity it completes a circuit
when in the position shown through the half ring F the ring K2 and the brush Q²
with the coils of an electro magnet U. (Figures VIII, I and II.) When a
current is thus passed through the magnet U2 its armature is attracted and the
detent gear V2 is relieved allowing the intermitter I to revolve. As will be
evident from the wheel connections shown the bevel wheel X2 will also revolve
carrying round with it the bevel wheel Y, the spindle N, and the brush L. When
the brush L arrives at the insulated space Z between the two half rings F1 and F2
the current is broken and the detent V2 is brought back to its original position
stopping the revolution of the intermitter, the governor and the other parts of the
train of wheel work driven from J2; and the mechanism will remain stationary
until the case A is again moved.
Should the case be moved so that the section F of the divided ring is brought
over the brush L, electric contact is made in a manner similar to that above
described only in this case through the section F¹ the ring K¹ the brush Q1 on to
the electro-magnet U1 (Figures VIII and II) relieving the detent V1 which
permits the bevel wheel X to revolve carrying the bevel wheel Y, the spindle N,
and the brush L in a direction opposite to that of the motion formerly described;
the current being as before broken when the brush reaches the insulating
segment Z.
A pointer or hand H may conveniently be attached to the spindle N so as to
indicate upon the dial that the mechanism has operated. It will be observed
from the description above given and from the drawings, that the hand H will
always tend to come to rest at the same indication upon the dial as that upon
which the pointer P (Figures I and VIII) was set.
Figures V and VI represent one form of the receiving mechanism, Figure VI
being a plan and Figure V a development through the axes of the parts m³, n, e³,
and 2 with the various communicating wheels.
The spring m2, communicates by wheel-work with the bevel 2 and the escape-
ment The coils of the magnet 2 are in circuit with a battery and with the
brushes C² and C2 (Figure I) so that at each revolution of the intermitter I² a current
is sent to the magnet u² (Figure V) the attraction of whose armature permits
the two-armed escapement e³ to make one half of a revolution, the depression of
the lever allowing the one arm of e² to be free but stopping the other, and
on the current being broken the lever again rising relieves the second arm and
stops the first. Each intermitted current sent through therefore allows the
escapement e² to make one complete revolution and the bevel 3 a given part of a
revolution. The motion of the bevel 2 is communicated through the bevel
the spindle n and to the hand h which thus accomplishes a given fraction of a
revolution for each complete revolution of the intermitter I³ (Figure 1) and thus
for each backward step taken by the hand H of the transmitting mechanism the
hand of the receiving mechanism makes one backward step.
to
Similar connections are made between spring m¹, escapement e¹ and the electro-
magnet which is placed in communication with the intermitter I¹ (Figure 1)
so that for each forward step of the hand H of the transmitting mechanism the
hand of the receiving mechanism makes one forward step.
It will be evident that the arrangement of one spring box shown in Figures I
and II for the transmitting mechanism may also be used for the receiving
mechanism; and again the arrangement of two spring boxes shown in Figures V
and VI may be used in the transmitting mechanism. An alternative arrangement
of driving gear for either of the two instruments is shown in Figures III and IV
in which M communicates motion through a wheel J to a spindle N' to which is
attached a travelling bevel wheel Y¹ which communicates the motion to a bevel

page_text: wheel X or to another bevel wheel X" according as the bevel wheel X¹ or the
bevel wheel X2 of the central spindle N is to be operated. To make the direction
of motion of one of these wheels be the reverse of that of the other an idle
wheel J is introduced into one of the two trains.
Instead of attaching the pointer P to the case A and providing means for
allowing the case to be rotated relatively to the base plate B we sometimes retain
the case fixed and rotate the contact rings F by means of a handle working over
the face of the glass E and attached to the rings F by means of an axis carried
through the glass in a manner commonly adopted in mechanical transmitting
instruments frequently used on board ship. The handle may conveniently be
guided on the rim of the case A and be bi-furcated so as to carry the pointer P
between its two arms.
The spring driving mechanism of the apparatus above described may in some
cases be conveniently replaced by a clock weight, an electro-motor, or other
driving mechanism.
Instead of the two-armed escapements above described we sometimes use escape-
ment wheels more or less similar to such escapement wheels as are customarily
used in clock-work mechanism. Such escapement wheels may, when constructed
with the requisite number of teeth be attached directly to the bevel wheels
and a². And correspondingly any suitable form of escapement lever may be used
in connection with such escapement wheels, so long as the lever is actuated by the
intermitted electrical currents sent by the intermitter on the transmitting
instrument.
Instead of having only one contact piece on the intermitter as above described
we may have two or more such contact pieces so as to send two or more intermitted
currents to the recording instruments for one revolution of the intermitter, and
in that case when we desire to have only one intermitted current sent for each
step of the transmitting mechanism, we may provide on the spindle of each
intermitter two or more arms to be stopped and released by the detent lever V
or V. It is further not essential that the intermitter should be carried on the
same spindle as the governor or other controlling device but may be connected
thereto through gearing.
When it is sufficient that the recorder hand should be capable of moving in
one direction only instead of backward or forward in accordance with backward
or forward movements of the transmitting mechanism, the contact ring F may
be constructed with only one insulated gap, and only one governor and one inter-
mitter will be required in the transmitting mechanism, and further the bevel
wheels X Y and X2 constituting the well known differential gear may be dispensed
with, the spindle N being driven directly by the wheel work. In this case also
only one of the two trains of gearing will be required in the receiving instrument
and the differential gear ay may be dispensed with.
The dial plates D of the transmitting apparatus and d of the receiving apparatus
may carry any series of orders, numbers or other indications and may extend
either for a complete circle or a portion of a circle as may be most convenient for
particular applications of the apparatus.
When it is not desired to have the pointers H and capable of making complete
revolutions stops may be introduced to limit their motion and such stops may in
some cases be of value in enabling the receiving instruments to be set by means
of the transmitter to read the same indication as that given by the transmitter,
should these be out of correspondence through having been disconnected or from
any other cause. In order to accomplish such adjustment it will only be necessary
to move the pointer P to one end of its travel and then to the other end of its
travel (allowing in each case sufficient time for the mechanism to follow) in order
to effect an adjustment of the instruments into correspondence with each other.
Figure IX represents an application of the instrument to the transmission of
straight line motions; the example chosen for representation being that of an
apparatus for transmitting indications of the level of water in a reservoir or the

page_text: height of the tide at a given station, but it will be readily understood that it can
equally be applied in a somewhat similar manner for a great variety of purposes.
In this figure T represents a transmitting mechanism which may be constructed
in the manner represented in Figures I and II with the exception that the
pointer P, the contact mechanism 1', the hand H, and the dial D may be omitted
and the case A fixed to the base B. N is, as before, the central spindle which in
this case carries a screw S upon which works a nut L to which is attached a brush
corresponding to the brush L in Figures I, VII and VIII. This brush moves
over two metal pieces F1 and F3 insulated from each other by the piece Z and
connected electrically respectively to the magnets U₁ and U2 as described with
reference to Figures I and II. Thus when the level of the water falls the metal
piece comes into contact with the brush L and an electric current passes
relieving the detent V₁ and allowing the spindle N to revolve carrying the nut
and brush L downwards until it again reaches the insulator Z when the mechanism
is stopped. Meantime the intermitter I will have sent a current once or oftener
to the receiving mechanism producing at it a corresponding change of indication.
The indications of the receiving mechanism may be shown on a dial or they
may be represented upon a straight scale by mechanism which will not require
to be explained in detail.
When it is desirable to have a permanent record of the series of indications
sent by a transmitter the receiving instrument may be arranged to-record upon
a paper drum; the drum being rotated uniformly with lapse of time by means of
a clock of any suitable kind or it may be rotated by any other suitable means
to record the series of observations otherwise than with respect to time; thus
for example, in a set of apparatus for indicating any series of orders the drum
might be caused to move one step when the recording pencil had come to rest
at any indications and in this manner record on the drum the series of messages
or records sent from the transmitter. One form of such a recording device is
represented in Figure X where R¹ represents a recording instrument constructed
substantially in the manner represented in Figures V and VI except that instead
of, or in addition to, the dial à and the hand h there is provided a screw s upon
which a nut h travels carrying with it a pencil or other tracing point which
traces a permanent record on a paper drum d, driven in any suitable manner.
Figure XIII represents a form of the apparatus as applied to the transmission
of indications of the motion of a swinging arm such for example as might be
connected to a ship's helm. In this figure T¹ represents the case containing the
transmitting wheelwork, F1 and F2 two contact segments insulated from each
other by means of a piece or gap Z, while L is, as before, a brush working over
these contact pieces. If now the framework carrying F1 and F2 be moved say
to the right bringing the segment F¹ into contact with the brush L the circuit
is completed with one of the electro-magnets (corresponding to U¹ in Figures I
and II) contained within the case T¹ the attraction of whose armature releases
the detent allowing the wheelwork and consequently the spindle N to rotate.
The spindle N being connected directly or by wheel and pinion or any other
suitable mechanical connection to the brush L the latter is caused to move towards
and on to the insulator Z, the intermittent currents being meantime sent to a
recording device constructed substantially in the manner indicated in Figures V
and VI.
When it is important to reduce the number of wires connecting the transmitter
to the recorder we may arrange the two intermitters I' and 12 in series and carry
two wires from the transmitter to the recorder in such a manner that when one
of the intermitters is operated the current travels in one direction and when the
other is operated it travels in the reverse direction. We may then provide
polarised armatures to the electro-magnets 7 and u² so that when the current
passes in one direction one of these armatures is attracted and when it passes in
the opposite direction the other is attracted. Again an earth return may he

page_text: substituted for a return wire. The nature of such electrical connections will be
so obvious that they need not be shown on the drawings.
In some cases it may be convenient to substitute a mechanical releasing
mechanism for the electrical one consisting of the contact maker F, the electro-
magnets U and U2 and the detents and V represented in Figures I, II, VII,
and VIII. Such a mechanical releasing mechanism is represented in Figures XIV
and XV. In these figures F, F¹ is a ring, one half I of which protrudes beyond
the surface of the other half F; L' and L are rollers moving over this ring and
connected by levers in such a manner as that shown to sleeves sliding upon the
spindle N. These sleeves are again connected to levers V1 and V2 which form the
equivalent of the detent levers V₁ and V2 of Figures I and II. In the position
indicated it will be evident that the roller L' being on the high part of the ring
the lever is raised allowing the governor G₁ (Figure 1) to revolve. The
ring being connected to the operating handle of the transmitting instrument
and the bracket L being connected to the spindle N it will be evident that with
suitable connections as above described and illustrated the bracket L will be
caused to revolve carrying the roller L¹ off the portion Fon to the portion F
when the lever VI will drop again and stop the mechanism.
In order to indicate the condition of the spring or springs of either the trans-
mitter or the recorder as regards winding up or winding down we sometimes
provide an indicator which may be constructed in the manner shown in Figure V.
In this figure w² w² represent two wheels which are actuated respectively by
a tooth 22 projecting from the spring box m² and a lever attached to the spindle
of the spring box. To the spindle of w² there is attached a pointer p² while to
the wheel w there is attached a dial d. For each rotation of the spindle in
winding up the spring m² the wheel w2 is moved one tooth by the lever 22 and carries
with it the dial and for each revolution of the spring box during the winding down
of the spring the wheel w² is moved one tooth by means of the tooth 22. A similar
counter may be used to indicate the condition of the spring m¹. When only one
spring is used to drive the transmitter or recorder as represented in Figures I
and 11 a similar counter may be used.
When the arrangement of spring shown in Figures III and IV is adopted it
will be evident that it will not be necessary to move the dial of the indicator
provided the spring box M be fixed to the case of the instrument as shown and
the drive be taken from the spindle through a ratchet wheel and pawl J". If
on the other hand the wheel J is attached rigidly to the spindle of the spring and
the spring is wound up by, rotating the box M an indicator of the kind above
described may be used. It may be pointed out that this latter system of winding
has the advantage that the spring can be wound up while the instrument is being
operated without interfering with its working.
When it is desired to communicate any indications or orders to a distant station
and to transmit back to the transmitting station indications that the receiving
instrument has moved in the desired manner we may arrange apparatus of the
kind already described in the manner indicated diagrammatically in Figure XVI.
In this figure T represents the transmitting instrument, F1, F2 the contact ring,
L the brush, Z, the insulating space as before, and R represents the recorder at
the distant station which is operated by intermitted currents sent in the manner
descrived from the transmitter T. In addition to the parts already described
and illustrated the recorder R contains on its escapement spindles, or spindles
driven in connection therewith, intermitters of the kind described in connection
with the transmitting instrument. These intermitters send currents to a
secondary recorder R¹ situated, near the transmitting instrument T. In this case
should the recorder R fail to operate through breaks in the circuit or otherwise
this fact will be indicated by the secondary recorder R' failing to follow the
motion of the transmitter pointer.
Another way of accomplishing a like result is shown diagrammatically in
Figure XVII, in which T is as before, the transmitting instrument, and R the

page_text: recording instrument, but instead of the haud H being operated by the wheelwork
of the transmitter it may be operated and controlled by means similar to those
described for the recording instrument, an intermitter or intermitters being
provided in connection with the mechanism of the recording instrument to send
intermitted currents to the transmitting instrument for that purpose. In this
case the brush L of the transmitter may still be operated directly from the wheel
work of the transmitter or it may be attached to the hand so as to be operated
by the secondary intermitted currents transmitted from the recorder R.
In some cases we omit the moving pointer P the contact ring arrangement F F
and substitute for these a double switch operated by hand which switch is arranged
to complete a circuit with the magnet U or with the magnet U2 as may be
desired. In this case the instrument is operated by completing one or other of
these circuits according as the hand is to move backwards or forwards, and the
contact is maintained until the hand H has reached the required indication when
the release of the switch stops the mechanism. In the meantime the intermitter
will have sent a number of currents to the recording instrument corresponding
to the number of steps which the hand H has been permitted to take, so that to
transmit any indication to the distant station it is only necessary to relieve by
means of the switch the forward or backward gear (or the single gear when only
one direction of motion is required) and to maintain the switch in this position
until the indicating hand of the transmitting instrument has reached the required
indication.
Again a like result may be obtained by directly releasing the detent V¹ or V2
by means of suitable levers, pressing buttons or the like.
'
Again the transmitting and receiving instruments may be so arranged that the
transmitting instrument is stopped or started by an electric switch or an equiva-
lent mechanical device and sends intermitted currents to a receiving instrument
while the receiving instrument transmits intermitted currents back to the trans-
mitung station which there control the motion of an independent mechanism
in such a manner as to cause corresponding indications to be shown at the two
stations.
An evident modification of the arrangement described above is made by
providing one driving system only in the transmitting instrument and connecting
the stopping and starting mechanism, (whether operated by electric currents or
directly by means of levers or other mechanical connections) to the indicating
hand of the transmitter through a mechanical reversing gear and providing means
for putting either of two intermitters into the battery circuit so as to receive and
control the motion of either the forward or the backward mechanism of the
receiving instrument as may be desired. Or again, one intermitter may be used
in connection with a reversing gear, the connections being so arranged that when
the reversing mechanism is so adjusted as to cause the pointer of the transmitter
to move forward the intermitted currents will be sent to the forward gear of the
receiving instrument and similarly for backward motions of the transmitter
pointer the current may be sent to the backward gear of the recorder.
Further, the intermitter may evidently be entirely separate from any indicating
device at the transmitting station and a recorder of the same kind as that provided
at the distant station may be provided at the transmitting station both of which
recorders are actuated by the intermitted currents; the recorders being connected
either in parallel or in series.
In any of the cases we have described a number of receiving instruments may
be worked from the one transmitting station at a number of different distant
stations, their electrical circuits being either connected in parallel or in series.
For many purposes it is preferable to connect them in parallel since then a break
in one of the circuits will not cause the stoppage of the others.
We may use transmitting and recording devices of the kind herein described
in conjunction with rangefinders of the single observer short base type, such

page_text: as those patented by the present applicants or in connection with rangefinders of
the dip or depression type the contact ring of the transmitting instrument being
operated by any suitable gear, in conformity with the motion of the working
mechanism of the range finder.
Again we may construct a "position finder" by the use of two transmitting
and receiving instruments of the kind described, in a manner illustrated in
Figures XVIII and XIX. In these figures T1 and T2 are two transmitting
instruments the contact rings of which are operated by attachments to two sight-
ing bars or telescopes P1 and P2 placed at convenient observing stations say on a
coast, in the vicinity of a battery of which B1 B2 and B3 may represent the positions
of guns. R1 and R2 Figure XIX, are two receiving instruments placed relatively
to each other, corresponding on any chosen scale to the positions of T and T.
The pointers of these receiving instruments move in azimuth in correspondence
with the motions of the telescopes P' and P2 respectively. The positions of the
pointers R and R³ may be read off from graduated arcs and the position of
an object upon which the telescopes P1 and P2 are directed may be deduced
therefrom. Or again the receiving instruments may carry instead of and in
addition to pointers, straight edged rulers h¹h the point of crossing O' of which
will indicate by reference to the centre of R' and R² the position of the object (
with reference to the centres of T1 and T2. The arms and 2 may be caused to
move over a chart so that they will indicate upon the chart the position of the
object O.
Again a centre B", may be taken to represent on the chosen scale, relative to R¹
and R² the position of a gun or battery B relatively to the transmitting instru-
ments P1 and P2, and a straight edged ruler B turning about B" will then, when
directed to the point O¹, indicate by its position the direction in which the
object O lies with reference to the gun 13. The direction of the aim B¹, may be
read off and communicated by word or by telephone or by means of a transmitting
and receiving instrument, to the gunner in charge of the gun B' who may then
set his gun by means of its azimuthal arc, into the correct training indicated in
Figure XX. The rulers h¹ and 2 may evidently be caused to move the ruler B""
automatically, by means, for example, of a slider upon B, having projections
passing into slots in the rulers h¹ and h², or any other suitable connections, and
again, the motion of the arm B may be caused to operate the contact ring of a
transmitter situated at B, so that the azimuth will be communicated automatically
to a receiving instrument situated near the gun B¹.
Again the distance of the point 01 on the ruler B from the centre B" will
indicate, on the chosen scale, the distance of the object from the gun B¹. This
range may read, off from a scale on the ruler B and transmitted by word or by
telephone, to the gunner at B' so that he can set the elevation of his gun as well
as the azimuth, although the object may not be visible from the position B¹
Figure XVIII, thus constituting the apparatus a complete "position finder
for gunnery service. Again the motion of a slider at 0 over the ruler B may
be made to operate a transmitting instrument in such a manner as that described
and illustrated above the reference to Figure IX.
"
Another method of applying our invention to the construction of position
finder is illustrated in Figures XXI and XXII. In these figures P represents a
dip or depression rangefinder indicating ranges by means of the angular depres-
sion of the object O below the horizon level of the station P and indicating at
the same time the azimuth of 0 relatively to the station P. B₁ represents a gun
or battery to which the range and training for the object O are to be communicated.
The azimuthal direction of the rangefinder P may be communicated by a trans-
mitting instrument T to a recording instrument R¹ (Figure XXII) and the range
indicated by P may be transmitted by a second transmitting instrument T either
of which transmissions may be effected by providing suitable connections to
operate the transmitters automatically or the transmitters may be operated by
hand in accordance with the indication of the rangefinder. If then a centre B

page_text: be taken in such a position relatively to R¹ as to represent on any chosen scale
the position of B₁ relatively to the axis of the rangefinder P then a point 0¹
moved along an arm h¹ so that the distance R¹ 01 represents on the chosen scale
the range of the point O from P, while the direction of ¹ corresponds with the
azimuth of the line P O, then the direction and distance of 01 from B will indicate
the azimuth and distance of the point from the gun B¹. The point 0¹ may
be moved along a ruler h¹ by means of a recorder R2 in a manner similar to that
described with reference to the nut in Figure X and again the range and direc-
tion of the point 0 from B₁ as indicated by the length and direction of the
line BO may be transmitted automatically to the gunner at B₁ by having a
pivoted ruler in the position indicated by B" 0¹ and by the use of such means as
those described above.
Again a single observer short base rangefinder such for example as that patented
by the present applicants, may evidently be substituted for the dip rangefinder P
(Figure XXI).
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:-
1. In electro-mechanical devices for producing corresponding positions or
indications in transmitting and receiving apparatus, the use of a ring (or of
equivalent straight or curved contact piece or pieces) having one insulated gap or
two insulated gaps, with a brush acting upon the same, the ring being operated
by hand or by mechanical connection to any moving part whose motions are to be
indicated at a distance, while the brush is actuated by the mechanism of the
transmitting instrument at a speed determined by the construction of the apparatus
and independent of the speed with which the contact ring or segment is moved,
the connection being such that when the brush is upon one of the contact pieces,
the mechanism of the transmitter is released and the brush is caused to move
over the contact ring and comes to rest when it reaches an insulating piece or
gap in combination with arrangements in the transmitting instruments for
sending intermitted electric currents to the receiving instrument the number of
such currents being determined by the distance through which the said brush in
the transmitting instrument has moved; all substantially as described.
2. The use of a mechanical device instead of the contact ring referred to in
Claim 1 to start the mechanism of the transmitting instrument which sends inter-
mitted electric currents to a receiving instrument and which device stops the
transmitting instrument when a piece actuated by the mechanism of the trans-
mitting instrument has come to a particular position with reference to the ring;
substantially as described.
3. In electro-mechanical transmitting apparatus the use of a switch, or equiva-
lent mechanical device, operated by hand, which serves to release an independently
driven and governed mechanism which moves a pointer over a scale (or the
equivalent) and sends intermitted electric currents to a receiving instrument
driven by independent means which currents control the action of the receiving
mechanism in such a manner that the motion of a pointer (or its equivalent) on
the receiving instrument corresponds to the motion of the indicating pointer of
the transmitting mechanism, all substantially as described.
4. In electro-mechanical transmitting apparatus the use of a contact ring, or
of a switch or equivalent mechanical device which serves to release an indepen-
dently driven and governed mechanism, which by means of intermitted currents
sent therefrom controls the motion of an independently driven mechanism at the
receiving station which mechanism again sends intermitted electric currents back
to the transmitting station and there moves a pointer over a scale in accordance
with the motion of a pointer at the receiving station driven by the mechanism
aforesaid all substantially as described,

page_text: 5. In electro-mechanical transmitting and receiving apparatus the use of a
contact ring or of a switch or equivalent mechanical device which serves to release
an independently driven and governed mechanism which by means of intermitted
currents sent therefrom controls the motion of an independently driven mechanism
at the transmitting station and also similarly controls one or more independently
driven mechanisms at one or more receiving stations substantially as described.
6. In electro-mechanical transmitting and receiving apparatus the use in the
transmitting device of a contact ring (or its equivalent) over which a brush moves
the said brush being controlled by intermitted currents transmitted from the
receiving instrument while the receiving instrument is controlled by intermitted
electric currents sent from the transmitting instrument all in such a manner that
the transmitting instrument shall be stopped when the brush reaches an insulating
gap or piece upon the said ring, substantially as described.
7. The use of such transmitting and receiving devices as herein described for
the transmission of azimuths, or of an azimuth and a range so as to constitute &
position finder, substantially as described.
00 1 1
1000
.
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicants' Patent Agents.