Improvements in Apparatus for Finding the Range or Position of Distant Objects.
Year: 1894

page_text: Date of Application, 5th Oct., 1894-Accepted, 22nd June, 1895
COMPLETE SPECIFICATION.
[Communicated from abroad by THE AMERICAN RANGE FINDER Co., a
corporation organized under the laws of West Virginia, United States of
America, and having its principal place of business at No. 40, Wall Street.
in the City, County, and State of New York, United States of America.]
Improvements in Apparatus for Finding the Range or Position of
Distant Objects.
I, HENRY HARRIS LAKE, of the Firm of laseltine, Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, do heraby
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 relates to apparatus designed for determining the range of distant
objects Its general principle is similar to that of the range finder forming
the subject of prior Patent No 18815 December 24th 1888, which is now in
use in many navies of the world. This principle 15 illustrated in Fig. 8, in
which A B represents a base line between the pivots of the two telescopes LL
Tis the object upon which the telescopes L L' are trained. The telescopes L L'
sweep ove ares of conducting material, with which they make contact.
battery,, is connected to the pivot points AB The arcs are connected in
Wheatstone bridge circuit by the wues a, b, c, d, and the galvanometer g is in loop,
as usual.
A
When the telescopes L and L' are placed parallel in the middle parts of their
arcs, then the resistances in the branches a bed of the budge are equal and the
galvanometer g does not deflect. When the telescopes are directed upon the object T,
then the galvanometer will be deflected (E M F. 1emaining constant) proportionately
to the resistance of the distance EC on the arc h, and as this distance measures the
angle EA C, which bears a relation to the distance of the object T, it follows that
the galvanometer may be at once marked in units of distance, and that the range
may be directly lead from it.
This
It is important, in this apparatus, that the galvanometer shall not be deflected
when the two telescopes are relatively parallel, no matter what then positions
may be on the conducting aics hh This, however, presupposes an exact equality in
resistance, per unit length, of the wires hh', over which the telescopes move
condition is, however, one that is seldom encountered, for, in practice, though the
telescopes may be parallel, the galvanometer almost always shows some slight
deflection Hither to it has been possible to avoid this error only by careful selection
of the wire forming the conducting ates.
Erior also arises from temperature affecting the conductors on one side of the
budge differently from those of the other side Ilero, even if the telescopes stand
parallel, and even if the conducting arcs h be physically the saine, still there will
be a deflection of the needle.
The principal object of the present invention is to provide means for eliminating
both of the foregomg som ces of error.
The invention funther consists in the construction of the instrument whereby it, is
rendered more compact in form, whereby the conducting wires over which pass the
sliding contacts are protected, and whereby error due to expansion or contraction of
the supports of said wile is eliminated.

page_text: ww
Fig 2 is a vertical section on the line 2 2 of Fig 1.
Fig. 3 represents, diagrammatically, the general arrangement of the instrument.
Fig. 4 is a plan view of the temperature-connecting device. Fig. 5 is a side
elevation of the same
Fig. 6 is an enlarged, detail, cross-sectional view of the contact arm controlling
mechanism.
Fig 7 is a plan view of the adjusting pus and their supporting bar
Fig 8 represents, diagrammatically, the typical arrangement of my ange
finder.
Figs. 9, 10 and 11 are Wheatstone bridge diagiains illustrating the changes in
position of the contact points e f.
Similar letters of reference indicate like parts.
The term
"
instrument in the following description means one of the two
instruments which together are united in Wheatstone bridge with the galvano-
meter and battery, all of these appliances combined forming the complete range
finder
The instrument is mounted upon a suitable standard, 1, to bring the telescope L
to the eye of an observer. On the pedestal 1 is rigidly seemed a cncular table, 3,
cairying a worm-wheel, 4 The mechanism is supported upon a metal plate. 5,
which in turn 15 supported on a pivot, 6, seated in pedestal 1, and has a
downwardly-turned Hange, 7. On the flange 7 may be marked a scale of any
suitable divisions by means of which (with the pointer 8) the plate 5 may be
adjusted in any definite position. Jominaled on the under side of the plate 5 is a
shaft, 9, which carries a worm, 10, engaging with the worm-wheel 4 The shaft 9
has a crank-handle, 11, so that, by turning said handle 11, the worm 10 is caused
to move around fixed wheel 4, the supporting plate 5 is thus caused to rotate over
any desned angle Upon the plate 5 ate bearings, 14, which rest upon insulating
blocks, 15. These beatings support metal pins, 16, npon which pins the box-wood
cylinder 17 rotates Each pin, 16, is secured to a netal cap, 18 which caps receive
the ends of cylinder 17. In the cylinder periphery is a spiral, in which is wound
the conducting wire h, having its ends connected to caps 18. On the brackets 14
are binding-posts, 19, which communicate by leaf-springs, 20, with the pins 16
When the wines a and c are connected to these posts there is en cut from one
binding-post 19 to its leaf-spring 20, to pin 16, to one cap 18 through the conducting
wne to the other cap 18, leaf-spring 20, binding-post 19 and wire a.
Upon one end of cylinder 17 and insulated therefrom is a gear-wheel, 21,
which engages with the gear-wheel 12 on and insulated from the shaft 9.
Therefore, when the handle 11 is turned the mechanism so lar described produces
both a 1otation of the supporting plate 5 on its pivot 6 and also a rotation of the
cylinder 17.
Also on plate 5 are two other brackets, 23, supported upon insulating blocks, 24
In these binckets is journaled a shaft, 26, the periphery of which is screw-threaded
and which also carries a pinion, 27, insulated from said shaft, which engages with
the gear-wheel 21 Electrical communication is made through one of the brackets 23
to the shaft 26, one of the wires leading from the battery being connected to the
bracket.
Upon the shaft 26 is a nut, 29, having an aim, 28, which terminates in a contact-
point, e, of platinum This point enters the spiral groove on the cylinder 17 and
bears upon the wire therein. Connected to the arm 28 and below its pivot point
1s a leaf-spring, 29*, (the nut being recessed to receive said spring), the effect of
which is to force the contact point e down into constant touch with the wire h
On the rear side of the nut 29 is a small roller, 31, and carried on the under side
of said uut by a spring-arm, 32, is another roller, 33. Before describing the use
of the two rollers, 31, 33, I will point out the third result which is caused by the
rotation of the handle 11-namely, the rotation through the gears 21 and 27 of

page_text: the screw-shaft 26 and the consequent movement of the contact point e along the
spual in the cylinder 17, the pitch of the screw on shaft 26 and the pitch of the
thread on cylinder 17 being the saine. The mechanism so far described and that
which will be described hereafter is all enclosed in a box, 34, upou the top of
which the telescope L is mounted in suitable standards, 35.
Let it now be supposed that the two instruments are placed at opposite ends of
a base line passing through the axes of the two cylinders 17: also that the contact
points ef in the two mstruments are at the middle points of the wires wound
upon the cylinders 17. The two telescopes L and L will then be parallel in a
position at night angles to the base line, and therefore directed at some point in
space infinitely distant The galvanometer will then show no deflection, the needle
indicating the infinity mark. Following the conditions represented in Fig. 8. let
one instrument remain in this condition, with the telescope pointing toward the
object T, while the other telescope is trained upon the object. To this end the
handle is tuned, thus rotating simultaneously the supporting plate 5 and thus
training the telescope upon the object, while at the same time through the gearing
already explained the cylinder 17 and the screw-shaft 26 are both rotated, causing
the contact point e to move over the wel in the cylinder 17-a distance which is
obviously proportional to the amount of angular train of the telescope. Therefore,
when the telescope shall have been trained upon the object T, the contact point e
n that instrument will have moved over a distance on the wire represented by
the distance EC in Fig 8.
I now come to the means for compensating for non-uniformity in the resistance
of conducting wires h' per unit length; but before considering the details of
the mechanism, I will explain more fully its principle If, in the simple toin of
Wheatstone bridge shown in Fig. 9, the four branches are exactly equal one to the
other (a===d), then, it the two contact points e and be placed exactly at
the angle between a and b and c and d, the bridge will balance, because a c=bd.
If the contact points ef be moved along the branches ad for equal distances, and if
the branches are assumed to be of uniform resistance, said points will then have
moved over equal resistances, represented by r, Fig. 10, and the bridge will still be
in balance.
It is obviously easy to place the contact points e and, as shown in Fig. 9, upon
the wire ou cylinder 17 so that the resistance in a shall equal the resistance
nb and so that the resistance in c shall equal the resistance in d; but we cannot
assume that a+b=c+d. If the equality of resistance does not prevail,
we shall have a different condition, which is illustrated in Fig. 11, in which,
although the contact points e and have been moved over the same distances over
the wires a and d, the resistances given corresponding to these distances are m in
one case and n in the other. Here, in order that the bridge may balance, we
must have
Hence, it after said contacts are moved the bridge does not balance, it is because a
correct ratio of m and n has not been obtained, and therefore the distance represented
by either m or n must be increased or diminished by causing an adjustment of the
contact points ef until the galvanometer no longer deflects.
thus
In practice, however, as already explained, the mechanism which trains the
telescopes upon the object and that which moves the arm 28 carrying point e over
the wire is actuated simultaneously by the crank 11. Consequently, if after, by
means, the telescopes were laid parallel in the two instruments and the points ef
correspondingly placed on the wires, there should still be found a deflection of
the galvanometer Is the points ef could not be adjusted to new positions (thus
varying mor n) by handle 11 without moving the telescopes out of parallelism
Therefore points ef must be moved independently of the tolescopes in order to give
the proper relation of m and n.

page_text: m'
m
་
Obviously in Fig. 11 the contact points e and may be moved for distances not
only which have corresponding resistances. m n, but for any other distances, say
such as have corresponding resistances m³, hence there must be a proper ratio
betnecu as well as between and so on, in order that the galvanometer, will,
show no deflection when the telescopes are in different positions, though
corresponding.
72
Upon standards, 36, on the plate 5 is a transverse bar, 37.
In this bar 18
disposed a number of pins, 38, having their lower ends, 39, turned at ught angles
The pins may be separately adjusted vertically m the bar 37 and cach pu 15
secmed in place as adjusted by means of its own set-screw, as 40 The pins are
also placed as closely together as possible (Fig 7), being staggered in position;
so that their lower ends, 39, form a substantially continuous guide-way, on the
upper side of which rests the roller 31 on nut 29 and against the lower side of
which bears the roller 33, also ou said nut When the surfaces of the ends 39 of
the pins 38 he all in the same horizontal plane, then the rollers will travel along
said surfaces as the out 29 moves along the screw-shaft 26 without causing any
vibratory or tilting movement of the ml 29 on its shaft. But if said ends are not
in the same plane but, in fact, form a cam surface (by reason of different vertical
adjustments of the pins 38 in the bat 37) then the tollers 31 and 33, in following
the irregular sun face, will cause more or less of a tilting of the nut 29, and the
result of such a tilting is the moving of the cud e of the aim 28 forward or backward
upon the wire in the cylinder 17.
Now, if I provide one pin, 38, for every successive degree of angular movement
given to the telescope L by the handle 11, then clearly the position of the contact
point e on the wire will be governed by the vertical adjustment of that pin in the
bai 37; and hence, as the telescope moves over its entire azimuth and as the
point e simultaneously moves over the weh, the position of the point e on said
wire will be slightly advanced or retarded for every degice of angular movement
of the telescope.
This will be better understood by considering the practical mode of adjusting
the apparatus. Let both telescopes be adjusted parallel with the points ef at the
middle parts of the cylinder 17, as shown in Fig 3, so that the galvanometer g
gives no deflection
The handles 11 in both instruments are now tuined to change
the angular position of the telescopes one degree, and by reason of the gearing
provided to rotate the cylinder 17 one revolution. The contact point e will then
be moved over a certain distance on wire h in one instrument, which distance mav
have the corresponding resistance m the contact point will also be moved over
a certain distance on wire in the other instrument which may have the cone-
sponding resistance n. If the natio is correct, the bidge will balance, and the
galvanometer g show no deflection. But assume the gulvanometer does deflect.
is therefore necessary to vary m or n. The 1ollers 31 and 33 are now respectively
above and below the fist pin of the series 38. This pin in either instrument is
therefore to be raised or lowered in its bar, so as to cause the point e to move
forward or backward on the wire until the galvanometer shows no deflection
This pin is then secured as adjusted by its set-screw. The proper clation of m
and n for that position of the telescopes has now been found and the apparatus
permanently adjusted thereto.
772
24
It
The telescopes are then changed in angular position another degree, and the
cylinders rotated another revolution. The rollers 31 and 33 ate now above and
below the second pin of the series, 38. The contact points e and have moved
over distances having corresponding resistances m' and '. The galvanometer
deflects. It is necessary to vary m' or '. The second pin is raised or lowered to
adjust the point e until the galvanometer shows no deflection, and this pin then is
secured by its set-screw. The proper relation of m² and n³ for the second position
of the telescopes has been found and the instrument permanently adjusted thereto.

page_text: So on for other positions of the telescopes differing successively by one degree,
until hually all of the pins 38 have been adjusted and their lower end- 39
produce a more or less irregular surface-the iegularity of which reflects, so to
speak, the variations in the resistance per unit length of the wires h h¹, which of
course are the only parts of the bridge branches traversed by the contact points e f.
As long as these wires remain m the instrument it is not necessary to re-adjust
the pins 38.
It will be plain that still any cause acting upon either the numerator or the
a+b
denominator of the fraction will throw the bridge out of balance. Such a
c+d
cause may result from temperature influences affecting the resistance of the
branches a+ differently from that of the branches + d. such as one instru-
iment getting hotter than the other 1 compensate for this source of eiror by
suitably modifying the lengths of the bridge branches. For this purpose I
provide the corrector which is represented in the diagram Fig 3 and also in
detail in Figs. 5 and 6. As shown in Fig. 3, 41 and 42 are arcs of wie. The
arc 1 interposed between the bridge bianches and d the are 42 between
the branches and e Over each are sweeps a contact finger, 43 and 44
the fingers 43 and 44 is connected the galvauometer g. It the fingers 43 and 44
be both considered as moved to the right of the diawing Fig. 3, then obviously
the length of the branches a and b will be increased, while that of the branches c
and will be diminished If said plates be moved to the left c and d are increased
and a and b diminished Therefore we simply move the contact fingers 43 and 44
equally in the proper duection to cause the galvanometer deflection to disappear
C
With
In practice, and as shown in Figs. 4 and 5, the wires 41 and 42 are mounted
upon the periphery of a disk, 45, of insulating material, supported on a suitable
standard 46. Through the disk 45 passes a shaft to which is rigidly secured at
one end au arm, 47, canying the contact finger 43. Loose upon said shaft on the
other side of the disk is an arm, 48, carrying the contact finger 44, said finger
being held on said aim and being capable of being tightly secured thereto by the
milled head 49. In the side of the disk 45 is a groove, 50, of dove-tailed shape in
cross-section, in which groove is a sunilaily-formed sliding piece, 51, provided with
a clamping-screw, 52, which passes through the aim 47. The fingers are adjusted
in place on the wires 41 and 42 either together or separately by hand, and after
adjustment both are clamped in place by the screw 52. The bridge branches a bed
connect in the manner already described to binding-posts 53, which posts are
electrically connected to the ends of the wires 41 and 42.
Loose upon the shaft 9 are two disks, 54 and 55, to either of which the handle 11
may be applied. These disks are held with sufficient rigidity to allow of the shaft
being turned by the handle by means of springs, 56, which are held against their
faces by screws, 57. The object of this construction is to prevent injury to the
apparatus in case the operator should cause the parts to come to the limit of then
movement suddenly, in which case the force applied to the handle 11 would cause
the disk to rotate on the shaft.
Also upon the shaft 9 is a disk, 58, graduated in minutes, in proximity to which
is a stationary datum mark, 59, on plate 5. The scale already referred to on the
flauge 7 of plate 5 indicates the amount of rotation of the plate on its pivot 6 in
degrees, and the disk 58 enables this rotation to be further measured in minutes
of arc.
It will be understood that in the instrument above described there is no auto-
matic adjustment for temperature contemplated. The instrument may be installed
ou a ship's deck in the open air, and it is hardly conceivable that thermometric
variations would be so rapid as to necessitate re-adjustment of the instrument
during any period of its ordinary employment, or even so extensive as to require
au eutile re-adjustment, even if the instrument were used in the coldest and hottest
parts of the day.

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 correspondents I declare that what I claim is :-
1. The combination, in a range finder, of two supporting plates rotary in a
houzontal plane, a rotary cylinder ou each plate, the said cylinders being located
at the ends of a basc line, a conductor spally wound on each cylinder, and,
also supported on each plate, a telescope or sight-bat, a contact finger, mechanisin
for moving said finger longitudinally on said cylinder and in contact with said
conductor, and intermediate transmitting mechanism between said support, said
cylinder and said finger, the said conductors and fingers being connected, as set
forth, with an indicating instrument in Wheatstone bridge electrical encuit,
whereby, when said telescopes are directed upon a distant object, the sand fingers
shall through said transmitting mechanism, be moved over definite distances on
eaid conductors, thereby disturbing the electical balance of the cucuit and causing
a deflection of the indicating instrument bearing a relation to the extent of
horizontal motion of the telescopes and to the range of the distant object.
2 The construction and arrangement, in a range finder of the type herein
described, of apparatus for varying the place of contact of the fingers ef on the
conducting wires corresponding to definite positions of the telescopes and
thereby compensating for variations in resistance per unit length in said
conductors.
3 The construction and arrangement, in a range finder containing a Wheatstone
bridge system as described, of the apparatus for modifying the relative lengths and
bence resistances of the bridge branches in order to compensate for the influence of
temperature unequally affecting opposite pairs of bianches of the bridge.
Dated this 5th day of October 1894.
IIASELTINE, LAKE & Co,
45, Southampton Buildings, London, W.C, Agents for the Applicant.