Improvements in Apparatus for Finding the Range and Position of Distant Objects.
Year: 1889

page_text: Improvements in Apparatus for Finding the Range and Position of
Distant Objects.
I, BRADLEY ALLAN FISKE, of The Beresford, New York City, United States of
America, Lieutenant United States Navy, 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 :-
-
The object of the invention is to provide an apparatus by which the individual in
charge of a gun may direct it upon a given target when the distance of said target
is not known to him, and even when he is unable to see the target by reason of fog
smoke, or other causes, from the point where his gun is located. The arrangement and
operation of the apparatus is such that observers stationed at points distant from the
gun itself, which points command a good view of the area within the range of said
gun, are enabled to discover the bearing and range of a target from the position of
the gun and to communicate to the person in charge of said guns said bearing and
range.
Reference being had to the accompanying drawings, Fig. 1 is a diagram
illustrating symbolically the general arrangement of the apparatus, and showing the
electrical connections. Fig. 2 represents the indicating devices as used at the gun
on a larger scale than is shown in Fig. 1. Fig. 3 represents a gun to which are
directly attached pointers or arms moving over graduated ares of conducting
material, so that the proper positions of the gun in train or in elevation may be
determined by an adjustment of the gun itself. Similar letters of reference indicate
like parts.
Referring to Fig. 1, A B represents a line of the parapet of a fort or other
defensive work. C, D, and E are guns located in said fort, and commanding the
area which includes the position of the target F. The object to be attained is to lay
all of the guns C, D, E correctly upon said target, although the persons in charge of
said guns may be unable to see said target, and ignorant of its bearing and distance.
For purposes of clearness, in the following description, the necessary operations
connected with one gun only, as E are referred to, premising that the same method is
followed in connection with every other gun. G and H are two arcs of conducting
material placed symmetrically with respect to a base line I J. These ares are
located at stations distant from the positions of the guns, and so situated as to
For this reason it is better that elevated
command a good view of said area.
positions should be chosen for said stations. K and L are two pivoted telescopes,
the free ends of which move over the arcs G and H and constantly maintain electrical
contact therewith. These telescopes may be directed upon the target F which
will therefore be at the intersection of the two lines of sight of said telescopes.
Located at a station distant both from the guns and from the positions of the
ares G, H, and preferably at a place safe from the effects of the enemy's fire, is
established another station, which, for convenience, is here termed a directing station,
On this chart
in which is a chart or map represented by the rectangle a, b, c, d.
the line A¹ B¹ represents the line A B of the parapet of the fort, and the point E¹
corresponds to the centre about which the gun E is laterally turned. The
chart a, b, c, d represents the area within the range of the guns CDE on some
definite reduced scale; so that distances taken on said chart represent actual
distances. On said chart is drawn a line l' J', corresponding to the base line I J,
and symmetrically disposed with reference to said base line are arcs of conducting
material G¹ and H¹. K¹ and L' are pivoted arms similar to the arms K L, the free
ends of which pass over and make constant contact with the arcs G¹ and H. Arc G¹
is similar in form and in electrical resistance per unit length to the arc G, and the

page_text: arc His likewise similar in the same particulars to the arc H. Extending from
the extremities of the arc G to the extremities of the arc G¹, are wires 1 and 2, and
extending from the pivoted telescope K to the pivoted arm K' is a wire 3, which
includes a battery. Connected in loop from the wires 1, 2, by a wire 4, is a
galvanometer M. It will be evident that the wires 1, 2, 3, 4, the arcs G G¹, the
battery, and the galvanometer M are connected in circuit in the form of a Wheat-
stone bridge; and that the effect of moving the telescope K for example, to the
right on are G, is to increase the resistance in the member 1 of the bridge, and
decrease it in the member 2; and that the same is true of a similar movement of the
arm K over the arc G¹. Therefore, if the telescope K be set at a certain position on
the arc G, it is simply necessary to set the arm K¹ to such a position on the arc G',
as that the galvanometer M shall show no deflection, when the bridge will, of course,
balance, and therefore, the angle made by the arm K¹ to the base line I J¹, will be
equal to the angle made by the telescope K to the base line I J. The extremities of
the arc H are connected to the extremities of the arc H₁ by wires 5 and 6, and the
pivots of the telescope L and arm L' are connected by wire 7, which includes a
battery. M is a galvanometer included in a loop 8 from the wires 5 and 6. It will
be seen that this arrangement of the two ares H H and circuit connections, is the
same as that of the arcs G G¹ and associated parts, and that therefore, when the
arm L is placed at the same angle with reference to the base line I¹ J¹ as
the telescope L is. placed with reference to the base line I J, the galvanometer M¹
will show no deflection, and the bridge will balance as in the preceding case. [t
follows, therefore, that if the two telescopes K and L be sighted upon the target F by
observers located at said telescopes, and if a third observer moves the arms K¹ L,
and at the same time watches the galvanometers M M³, he will have placed the
arms K L at precisely the same angles as the telescopes K L, when both galvano-
meters show zero reading. Inasmuch as the chart a, b, c, d bears a definite
proportion to the area which includes the position of the target F, it follows that the
armis K L will intersect at the position F1, which would represent on the chart the
actual position of the target F.
Upon the chart a, b, c, d are pivoted three pointers, only one of which, for con-
venience, is shown at N; and these pointers are pivoted at the points as E' which,
as already stated, correspond to the centres of horizontal motion or train of the
guns C, D, E. Consequently, if the pointer N be turned on its pivot, it will
correspond to the positions of the gun E when said gun is turned on its pivot. One
arm of the pointer N is long enough to sweep over the area which includes the
target. The other are bears upon and makes electrical contact with an arc O of
conducting material. At the gun E is arranged a similar arc of conducting material 0¹,
and sweeping over this are is a pivoted arm P, the free end of this arın making
contact with said arc. The extremities of the arc O¹ are connected to the extremities
of the are O by wires 9 and 10. The pivot point of arm P is connected to the pivot
point E¹ by wire 11, which includes a battery. Located near the arm P, is a galvano-
ineter arranged in a loop circuit 12 from the wires 9 and 10. It will be apparent
that the arcs 0 0³, the galvanometer Q, and the battery, are here connected in a
Wheatstone bridge in precisely the same manner as are the ares G G¹, and circuit
connections; and therefore, for the same reasons already explained with reference to
the arcs G G and the moving arms K K', it follows, that when the arm N and the
arm P are both set at precisely the same angle, the galvanometer Q will show no
deflection and the bridge will balance. Consequently, if an observer at the chart a, b, c, d
brings the arm N upon the point F¹, which is the intersection of lines drawn from
the arms K' I, he will have established the angle at which the gun E must be laid
with reference to the base line I J in order that said gun may point in the direction
of the target F. As shown in Fig. 1 the arms K' L' are prolonged so as to intersect
at the point F¹. At the same time, by the movement of said arm N over the arc 0,
the observer throws into the circuit a fractional portion of said are having a resistance
proportionate to the angle. And hence, in order to interpose an equal resistance in
the bridge, the person in charge of the gun at which is located the arc O¹, must

page_text: move the arm P over a similar angle. He knows that he has moved it over this
similar angle by the galvanometer Q reading zero. He has, therefore, simply to read
the angle from the arc O', and lay the gun at the same angle.
I have so far provided for the training of the gun upon the target, but not for its
adjustment for range. This adjustment I make in a similar manner, as follows: I
measure the distance of the target from the gun by any known method, such, for
example, as by measuring the length on the chart between the point Fi and the
point E. R is an are of conducting material, and S is a pivoted arm sweeping over
and making contact with said are. R is an are similar to the arc R, but located near
the gun E. S' is an arm similar to the arm S, and moving over and making contact
with the arc R. The extremities of the arcs R' and R are connected by wires 1, 3
and 1, 4. The wire 15 connects the pivot points of the arms S S and includes a
battery. A galvanometer T is include l in a loop circuit 16, from the wires 13 and 14.
It will be seen that the arrangement of the arcs R R' and their arms, is substantially
similar to the arrangement of the arcs 0 0¹, or H H or G G¹, with their associated
arms. Consequently, when the arm S is placed at a certain angle, the galvano-
ineter T will show zero, when the arm S is placed at that same angle, but not
otherwise. The electrical resistance of the two arcs is similar for equal divisions of
said are; ant for each division of each arc, as for example, for each degree, the
resistance corresponds to a certain distance lineally measured. Consequently, if the
distance F E is known, the observer has only to set the arm S over such a fractional
portion of the arc H, as that there shall be thrown into the circuit a resistance
corresponding to said distance F¹ E¹. In order to balance the bridge between the
arcs R¹ R, the observer at R¹ must place the arm St at the same angle as that at
which arm S has been set. He will thus learn the angle at which said arm S has been
set, and consequently the distance of the object. Then, it remains simply for him to lay
his gun at the proper elevation corresponding to said distance; using for that purpose
the ordinary sight bar or quadrant. In the drawing Fig. 2, I have shown a convenient
arrangement of the arcs R¹ O', and the galvanometers QT; so that an observer, can
easily manipulate the arms P and S¹ by watching the galvanometers Q T.
In the case just described, the observer at the chart a, b, c, d, signals the distance
or range of the object to the person at the gun, and the latter adjusts the gun at the
proper angle of elevation to cause it to project its shot over that range. It will be
obvious, that instead of signalling the range, the observer at the chart a, b, c, d, inay,
himself, determine the proper elevation of the gun, and set the arm S at that angle.
The person at the gun will then place the arm S at the same angle, in the manner
already described, and thus learn at once the angle of elevation of the gun.
The system, so far as described, involves the signalling to a person stationed at the
gun, of information as to the range and bearing of the target, or instead of the range
an angle of elevation corresponding thereto, which enables him properly to lay his
gun. It is not, however, at all necessary, that this information should be imparted to
any person at the gun or that, in fact, any one manipulating the piece, should be
informed what the exact elevation or the exact training of the gun is to be. Instead
of arranging the arc R¹ away from the gun, it may be applied directly to the gun
carriage, as shown in Fig. 3: and the arm St may be applied to the gun itself; so
that the movements of the gun on its trunnions for elevation or depression, will
cause the arm S₁ to sweep over the arc R. And so also, are 01 may be arranged,
on the flooring adjacent to the gun, and the arm P may be connected, for example,
to the gun carriage. So that when the gun is trained, and so turns upon its pivot,
supposed for example, to be at the point P¹, the arm P will sweep over and maintain
contact with the arc O'. It will be seen, therefore, that when the observer at the
chart a, b, c, d places the arm N at the proper angle on the arc O, it will be
necessary simply to train the gun, Fig. 3, until the arm P, which it carries, makes a
corresponding angle on the arc O'. And similarly, the observer at the chart a, b, c, d
sets the arm S at an angle corresponding to the elevation of the gun for the range
indicated between the points E and F on the chart, and the gun itself is then
elevated or depressed until the arm S¹ makes a similar angle on the arc R', the

page_text: direction to be given to the gun in both cases, being shown by the indications of
the galvanonometers Q and T as before.
In the foregoing discussion it has been assumed that the conducting wires offer no
resistance. While this is not theoretically true, any one skilled in the art can easily
make the necessary compensatory adjustments.
Instead of having the chart a, b, c, d at a distant point, it may be located at one
of the observing stations, in which case one pointer, as K', may be governed
mechanically by the telescope at said station instead of electrically as here shown.
It will also be apparent that the foregoing system may be applied without material
change to a vessel of war, the side of the ship, for example, taking the place of the
line A B of the fort, the telescopes K and L being located, for example, at the
bow and stern of the vessel, and the chart a, b, c, d at any protected point, as
below the water line.
By the term indicating apparatus herein used is meant any apparatus which will
reveal the fact of a difference of electrical potential.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The apparatus for finding the range and position of a distant object operating
and arranged substantially as hereinbefore described, and as follows, to wit; first by
directing two alidade arms K 1. moving over ares G H of conducting material in line
with said object; second, placing two pointers or arms K' L' moving over arcs G' H¹
of conducting material located at a distant station and similarly disposed with
reference to a base line at the same angle as said arms K L, and thereby establishing
an electrical balance in each of two circuits, one circuit including the arcs G G¹,
arms K K¹, a battery, and an indicating apparatus, the other circuit including the
arcs H H¹, arms I L', a battery, and an indicating apparatus; third, noting the point
of intersection of the lines of direction of the arms K¹ L.
2. The apparatus for finding the range and position of a distant object with
reference to a predetermined point, operated and arranged substantially as herein-
before described, and as follows, to wit; first, by directing two alidade arms KL
moving over arcs G H of conducting material in line with said object; second, placing
two pointers or arms K' L' moving over ares G₁ H' of conducting material located
at a distant station and similarly disposed with reference to a base line, at the same
angle as said arms K, L, and thereby establishing an electrical balance in each of
two circuits, one circuit including the arcs G G³, arms K K¹, a battery, and an
indicating apparatus, the other circuit including the ares H H', arms L L', a battery,
and an indicating apparatus; third, noting the point of intersection of the lines of
direction of the arms K' on a chart a, b, c, d representing the area including the
position of said distant object on a reduced scale; fourth, determining on said
chart the distance and bearing of said point of intersection from said predetermined
point.
3. The apparatus for finding the range and position of a distant object with
reference to a predetermined point, operated and arranged substantially as herein-
before described, and as follows, to wit; first, by directing two alidade arms K L
moving over arcs G H of conducting material in line with said object; second,
placing two pointers or arms KL moving over arcs G₁ H¹ of conducting material
. located at a distant station and similarly disposed with reference to a base line at the
same angle as said arms K L and thereby establishing an electrical balance in each of
two circuits, one circuit including the arcs G G¹, arms K K¹, a battery, and an
indicating apparatus, the other circuit including the arcs H H', arms L L', a battery,
and an indicating apparatus; third, noting the point of intersection of the lines of
direction of the arms K¹ 1 on the chart a, b, c, d, representing the area including
the position of said distant object on a reduced scale; fourth, determining on said
chart the distance and bearing of said point of intersection from said predetermined
point; fifth, signalling to the said predetermined point, the said bearing and distance

page_text: 4. The apparatus for finding the position of a distant object with reference to a
predetermined point, and indicating the same at said point substantially as herein.-
before described, and operated and arranged as follows, to wit; first, in determining
the position of said object; second, marking said position on a chart or map
representing on a reduced scale an area including the position of said object; third,
directing a pivoted index or pointer to point to said marked position, the said pointer
moving over and making contact with an arc of conducting material; fourth, moving
an index or pointer located at said predetermined point and traversing a similar are
of conducting material until an electrical balance is attained in a circuit including
said ares, a battery, and an indicating apparatus.
Dated this 5th day of March 1890.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.