Year: 1888

page_text: Date of Application, 24th Dec., 1888
Specification Accepted, 25th May, 1889
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings, in the County of Middlesex, 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 invention consists in an apparatus for finding the distance or position of a
distant object. It depends upon the determination of the angular change in position
of a body moving about a center by measuring the electrical resistance of a conductor
extending between the initial and final positions of said body.
The accompanying drawings are, (Fig. excepted,) all electrical diagrams, not
drawn to scale, and symbolically represent the invention. In Fig. 1 is shown a
Wheatstone bridge, in one member (a), of which, is arranged an arc and a movable
arm traversing the same. In Fig. 2, is shown a Wheatstone bridge having arcs and
movable arms arranged in two members (a, b). In Fig. 3 is shown a Wheatstone bridge
in which arcs connect adjacent members, as a c and bc, and movable arms sweeping
over said arcs are conneted to the battery. Fig. 4 is a mathematical diagram
illustrating the method of determining the angle ATC. Fig. 5 shows a disposition
of the range finder in connection with a galvanometer, and Fig. 6 the same in connection
with a telephone. Similar letters of reference indicate like parts.
In Fig. 1 let a, b, c, d, represent the four members of an ordinary Wheatstone bridge,
and 9 the transverse member in which is connected the galvanometer g'. A battery f
is also connected to the bridge in the usual way. In the members c and,d, are placed
the fixed resistances c and d¹, and, in the member the variable resistance 6' also as

page_text: "
and
usual. One wire, from battery, however, connects to the end of member
also to the pivot 1 of a swinging arm i. The extremity & of arm i moves over and
maintains electrical contact with an arc h, of conducting material, which has one
extremity connected, as shown, to the member a of the bridge. It is obvious, that
when the arm is in the position shown in full lines in Fig. 1, then the current will
traverse the whole are hand when said arm is in the position indicated by dotted-
lines, Fig. 1, then the arch will be cut out, and the current will pass directly to
member a.
Now assume the arch to be made of such material, and so proportioned, that its
electrical resistance to a current traversing it, will be proportional to the length of
arc included between the contact end of arm and the connecting point j of
member a, with said arc. Therefore the resistance interposed in the member a
of the bridge will be commensurate with the angle j, l, k, and if this resistance be
known, the angle is also known.
Let it now be assumed, that the galvanometer gl and variable resistance be
located at some point distant from the moving arm i, from which said arm is invisible
or inaccessible. Clearly then, an observer stationed at the galvanometer g' and
resistance b¹ can, by noting the galvanometer and adjusting the resistance in the
usual way, determine the resistance equilibrating any position of armi along the arch,
and so discover the angle of adjustment of said arm. Or, having adjusted the
resistance 6' at some given figure, the observer may, by simply noting the galvano-
meter or any other suitable indicating device, visual or audible, determine when the
armi is placed at a desired angle corresponding to the adjusted resistance; and this
indicating device may obviously be at the place where the moving arm is located, so
'that the operator there, may thus know when he has placed the arm at the
pre-determined point; or at the distant station, so that the operator in charge of the
resistance b¹, may know that the arm has been adjusted properly; or two indicating
devices in the same circuit may give warning to both operators as above simul-
taneously. Various practical applications of this apparatus will readily suggest
themselves to those skilled in the art. Thus, for example, the elevation or training
of a gun may thus be determined or recognized from a distant point, the longitudinal
axis of the gun corresponding to the arm : or the arm i may be the needle or pointer
of any apparatus actuated in any way, as for example, the pointer of a steam gage,
..in which case, the angular movement of the needle may be proportional to the
pressure, so that the determination of the resistance at the distant point, reveals the
pressure, or so that the adjustment of the resistance at some fixed point, may result
in the needle, on reaching a certain angle, actuating an alarm.
Referring now to Fig. 2, it will be apparent that in lieu of the variable resistance 61
in the member b, there is arranged an arc h', and swinging arm . The arc ¹ is
connected at one end j¹ to the member b, and the swinging arm i¹ makes contact at
one end with said are, and to its pivot is connected the member d. The arrange-
ment and construction of arc h¹ and arm i¹, is similar to that of arch and arni ¹.
..Consequently, when the arm i is set at a certain point on the arc h, the arm must
be set at the corresponding point on the arch, in order that the resistance' of the
lengths of the arcs h h respectively, between the point & and point h and point kaud
point may balance. Hence if the arm k be set at a certain angle, the observer at
arm may recognizes that, angle by noting the position of the arm and the
galvanometer as before.
"
It will be observed, however, that the effect of moving the arm i over are h, is
practically to lengthen or shorten, or to interpose more or less resistance in the
member a of the bridge; and by operating the arm, a like effect is produced in
the member b. The resistances or lengths of the members c and d remain
*. unchanged.
".
Referring now to' Fig. 3; there is shown an arrangement which forms the basis of
the specific embodiment. of the invention more particularly hereinafter described." In
said Fig. 3, the arc is connected at its respective ends j J, to the members a, cand
the arch is similarly connected at J to the members b, d. The battery wires

page_text: connect to the pivots of the arms as before. Now when the arm is moved
from its middle position on its arc, towards j, less resistance is caused in the
member a, and more resistance in member c; and when moved in the opposite
direction, the reverse occurs. So also a similar effect is produced by moving arni ;
and thus the resistance offered by all four members of the bridge, may be affected,
instead of that due to only two of them; and differential results may be obtained, as
will more fully be apparent in the following description of a device for measuring
distances, such as a range finder for guns.
Referring to Fig. 4, let T be the position of the object, the distance of which, from
the point A, it is desired to ascertain. Let A B be any short base line. Draw AC
at right angles to BT, E A parallel to B T, and prolong A T as to !).
AT AB sin ABC, cosec. ATC.
A B being the measured base line is known, and the angle A B C at the point
of observation is easily determined, so that the angle ATC remains to be
found. But ATC=DAE, and DAE is subtended and measured by the arc GH.
Arc GH Arcj H- Arc G and Arcj H = Arc J¹ K.
Hence, Arc GH Arc
=
K-Arcj G.
In Fig. 5, the diagrams Figs. 3 and 4 are combined, as before being swinging
arms traversing the arcs h, and the connections a, b, c, d, of the bridge being
present also as before. Let the arms and represent telescopes both directed upon
the object T. The arcs j G and j¹K not being equal, the bridge will, not balance.
But when the telescope i is moved to the line E A, then the bridge will balance.
But the distance thus moved is the Arc GH-the length of which may be read
off from the arch itself.
It will also be apparent, that by a simple trigonometrical calculation, the
distance BT may be found. The base line A B and the lines AT and BT then
being known, the position of the object T may be readily determined, so that the
apparatus may be used as described, not only to find the range, but also the position
of an object.
The operation in detail of finding the distance A. T is very simple. The observers at
the respective telescopes and direct their lines of sight upon the object. The
observer at i, notes the angle j AG or length of are, G. He then moves the
telescope, until the galvanometer g', which may be placed conveniently near his
position, shows no deflection, and notes the angle jA H or length of Arc; H. The
difference between the arcs j G and H, equals the arc G H, whence the angle ATB,
as already explained. The foregoing arrangement (Fig. 5) involves the deter-
mination of the angle ATB, and hence the distance A, T, by the observer at the
arm or in other words, by an observer at the base line. The disposition of the
apparatus whereby an observer; at a point distant from said base line, may at once
read off the distance A, T, from a suitable scale, will now be explained.
Referring to Figure 6, the members a and b of the bridge are connected to opposite
extremities of a bar, m n of conducting material, and the members c, d are connected
to the extremities of a similar and parallel bar o, p. Adjustable upon said bars o, p
and m, n is a slider r,, having a middle portions of insulating material, so that the
current from bar m, 'n for example, does not pass across said slider to bar o, p but
proceeds by the wire g through the telephone g", which here takes the place of the
galvanometer g' in the preceding figures. Interposed in the battery wire as at t, is
any form of automatic circuit breaker or "buzzer," the object of which is to produce
an audible sound in the telephone g¹¹.
The telescopes i and are fixed upon their respective arcs in the manner stated.
The arcs are adjusted upon the base line, so that said base line may pass through
the centre of both. This may be done by sighting the telescopes of the instruments
one upon the other, in the manner well known in the use of sextants and theodilites.

page_text: ·
:
;
It is not, of course, essential that the corresponding. diameters of the arc should be
parallel with the base line the corresponding diameters should however he parallel
with each other, and it is essential that the centre on both arcs should be put on the
base line.
?"
Suppose, now, that the telescopes i and are sighted upon the distant object T, as
:before, and that the slider is at the middle point 1 of the parallel bars m, n and o, p.
The resistances in the bridge will obviously not balance, and the sound of the "buzzer "
will be heard in the telephone g₁. It has been already explained in connection with
'figure 5, how, by moving telescope i to the point H, the resistance might be balanced,
and if that were done with the arrangement shown in Figure 6, the fact would
obviously be indicated by a cessation of sound from the telephone. But now, let it be
assumed, that the telescope i, after being sighted upon the object T, is not moved: or
in other words, that the observers respectively at the two telescopes i and i, simply
adjust their instruments in line with T. Obviously then the distance on the bridge
from to G (member a) is less than the distance from to k (member b) by the
length of the arc G H. Similarly, the distance on the bridge from 1 to g (member c)
is greater than the distance from 1 to k (member d) by the length of are G H.
Now, let the resistance per unit length of the bars m, n, o, p, be made equal to, or
with some definite relation to the resistance per unit length of the arcs h h¹; and lay
off on bar mn, a distance 73 and on bar o p a distance 13, said distances being such
that the resistance due thereto, will be equal to that of the arc G H. Clearly, if the
end of the slider, be moved to the position 2 on bar m n, the member a will be
increased, and the member b will be diminished by the distance 22, which offers a
resistance equal to one half that of arc G H, and if the end r¹ of the slider be moved
to the position 2 on bar o, then the member c will be decreased, and the member d
increased by the distance 73, which also has a resistance equal to one half of are G H.
As both ends of the slider move simultaneously, it follows, that when its extremities
are adjusted in the position 2, then the bridge will balance and the sound in the telephone
will cease.
Applying this practically, let the bars m n, op, be laid off in suitable scale divisions
from r to n and r¹ to p. The two telescopes and being sighted on the object,
the distant observer listens at the telephone g¹, and moves the slider along the
bars m, no, p, until the sound ceases. The scale marked on the bars then shows an
indication corresponding to the length of arc G H ; or if desired, actual distances
corresponding to such indications.
To illustrate the practical utility of the apparatus, the following instances may be
given. The telescopes suitably mounted upon their arcs h, are given to two
observers, who proceed to a skirmish line, or to any other advanced position, and
selecting a base line of pre-determined length, train their instruments upon any
desired point of an enemy's works or columin. The fact that this is done may be
indicated by any suitable flag signal, or by one sent electrically to the rear over the
bridgo connections. The observer at the telephone g¹ may be supposed to be stationed
in proximity to a battery of guns ready to open fire. As soon as the signal is sent
that the telescopes are sighted, the observer at the telephone adjusts the slider rr³,
until the sound in the instrument ceases, and then determines the range from the
marks on the bars m n, op, when the guns are laid accordingly.
i
The invention is, however, especially applicable to use in connection with pneumatic
guns, for the projection of shells charged with high explosives. A gun of this type
is placed in the bow of a vessel, at a certain fixed elevation, for example, 18°-and the
range of the projectile is regulated by varying the air supply admitted to the gun.
It thus becomes highly important to determine the distance of the target with all
possible accuracy. The two telescopes may be mounted on opposite sides of the
vessel's upper deck, her breadth of beam, for example, being the known base line;
while the telephone gl may be located below and convenient to the air regulating
valve of the gun. The observers on the upper deck, train their telescopes on the
object, and the observer at the telephone determines the distance in the manner
already described, and in accordance with this determination, adjusts the valves.

page_text: Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, as communicated to
me by my foreign correspondent I declare that what I claim is
1. A range and position finder constructed substantially as hereinbefore described,
and depending upon the measurement or balancing of the electrical resistance offered
by a conductor included between the initial and final angular positions of sight tubes
directed from opposite ends of a base line upon the distant object.
2. A range and position finder containing the pivoted radial sight tubes located at
opposite ends of a base line, and moving over arcs of conducting material, having a
known ratio of electrical resistance per unit length, in combination with a source of
electricity, circuit connections and indicating or signal mechanism, the whole
operating and arranged substantially as herein shown and described.
3. A range and position finder containing the combination of the four
members a, b, c, d, of a Wheatstone bridge, two arcs h³, respectively interposed
between members a, c and b, d, two pivoted radial arms or sight bars i ¹, respectively
having their free ends moving over and maintaining electrical contact with said arcs, a
source of electricity, having one pole connected to one of said arms, and the other pole
connected to the other of said arms: a circuit breaker interposed between said source
of electricity and one of said arms, two bars of conducting material, respectively
interposed between members a, b and d contact pieces adjustable upon each of
said bars, a loop conductor connected at its ends respectively to said contact pieces,
and a telephone in said loop.
1
1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London,
Agents for the Applicant.