ROVEMENIS IN RANGI FINDERS
Year: 1888

page_text: Date of Application, 8th June 1888
Complete Specification Left 20th Feb
1859
Complete Specification Accepted, 4th May, 1889
I, PATRICK JOHN LYNAM of Woodlawn, Mount Pleasant, County Louth, Civil
Engineer do hereby declare the nature of my invention for IMI ROVEMENIS IN RANGI
FINDERS to be as follows
-
The invention applies to that class of Range Finders in
hich the ringo is
found by two observers with two angular instruments connected by bist line of
known length, and consists in forming the angular instruments so as to be cach
moveable about a vertical axis which is used is a handle, and fixing the base linɩ
( suitable wire rope or string) by swivel joint to a projecting arm on ech ngalu
instrument When the two observers pull the two angular instruments pirt by the
bandles the tension of the bisc line, acting on the projecting arms, swings the ungulu
instruments round their verticil ixes until they assumie approximately hxed position
relatively to one another, which facilitates the angular micasurements
Dated thia Sixth des of Inne 1888

page_text: I PATRICK JOHN LYNAM of Woodlawn Mount Pleasant, County Louth, Civil
Engineer, do hereby declare the nature of my invention for IMPROVEMENTS IN RANGE
FINDERS and in what manner the same is to be performed, to bɩ particularly
described and ascertained in and by the following statement
The Invention applies to that class of Ringe Finders wluch require two observers
and in which Ringes are found by means of two Agu'r Instruments (that is
Instruments for measuring ingles) connected by Bise Line of known length, and
consists in forming the Angular Instruments so as to be cich moveable about i
vertical axis, and ittichung the Bise Line to ich Instrument in such a manner that
when the Instruments ire pulled apart the tension of the Bast Line swings the
Instruments round their vertical axes until they assume approximately fixed position
relatively to the Bise Line and to each other
In finding a range each Instrument requires to be adjusted relatively to the Base
Line when sighting the distint object whose Range is to be found Also the Instru-
ments require to be pulled apart to tighten ud strughten the Base Line With the
arr ingement described above, when the Instruments iro pulled part to tighten the
Base Line, the tension of the Bise Line icting on the Instruments automatically
swings them round until they are nearly or quite idjusted relatively to the Base Line
This intomatic idjustment relatively to the Base Line may not perhaps be exact
(owing to friction and to the fact that the Base Line may not be quite straight) but
it is sufficient when the Instruments ir constructed on the principle of the Sext int,
with wide fields of view, and in other cases although not sufficient it saves time and
trouble
The Base Line is a metal chun, or wire, or it may be made of silk, or any light
and strong material
The Angular Instruments may be constructed on any known principle such
that of the Sextant or of the Plane Table I prefer to construct one Inst. ument so
as to measure a fixed angle, the other being graduated to shew hanges instead of the
corresponding angles
The vertical axis of each Instrument is a spindle of steel or other suitable initerial,
which turns in bearings of brass or other suitable material The vertical axis
connects the Instrument with the Hindle or Bayonet attachment by which it is held,
or with the Stand on which it rests 1 prefer to fix the spindle under the center of
the Instrument ind pass it through bearings in the center of the Handle, Biyonet
att ichment, or Stand, but the vertical axis may be placed in any position provided
that when the Instrument is held or placed in position to take an observation it can
swing freely round the vertical axis
The Base Line is attached to each Instrument at point as fir from the verticil
axis as can conveniently be arranged so that the tension of the Base Line may hive
sufficient leverage to overcome friction in the vertical axis The attachment I prefci

page_text: If
to make by a Swivel joint but a ring or a knot will be sufficient in some cases
the Insti uments be very small, or if they be constructed on principle which requires
very accurate adjustment relatively to the Base Line, each Instrument must be pro-
vided with a Projecting Arm to the end of which the Bise Line is to be attached If
the Instruments are constructed on the principle of the Sextant the Projecting Arms
may generally be omitted
In the innexed drawings is shewn the mode of application of the Invention to
Angular Instruments constructed on the principle of the Sextant Figure 1 is a
plan showing the instruments A and B in their proper relative position for taking the
Range of the Distant Object D The Base Line is shown at C Figure 2 is an
elevation shewing the Instruments A and B and Base Line C but in this figure the
Right hand half of each Instrument is shewn in Section, the plane of section pissing
through the center of each Instrument
The Instrument A is simply an Optical Square, the Mirrors E and E₁ being fixed
at an inclination of forty five degrees so as always to measure a right angle The
Instrument B has one Mirror R fixed, but the other Mirror R, is placed on an Index
Arm S which is pivotted at S₁ and at the other end S, his a graduated are (or any
suitable gearing to multiply the movement) so that the angle of Inclination between
the Mirrors R and R₁ can easily be read off is in an ordinary Sextant
being graduated to read angles the Instrument B may be graduated to read the corre-
sponding Ringes
Instead of
The Instrument A. is fixed on the Spindle F the case of the Instrument being
riveted or screwed to a flange F₁ on the Spindle F and the Spindle turns freely in the
This handle is meant to he held
bearings H, H, which are fixed on the handle H
in the hind The Base Line C is attached to the Swivel Joint G which is fixed to the
case of the Instrument
In using this Instrument A the Observer should look through the Eye-hole K and
make the Distant Object D (seen direct over the Mirror E) cover the image of the
Instrument B (seen in the Mirror E by double reflection from the Murors E and E₁)
by slightly shifting his position The Observer can see by double reflection objects in
the Field of view M M₁ M, M, the angular width of the Field of view being
determined by the size of the Mirrors E and E₁ The Swivel Joint G is pliced
Centrally in this Field of view, so that when the Instrument is held by the handle
and pulled to the right to strughten the Base Line the tension of the Base Line
tends to swing the Instrument round on it's vertical axis until the center of the
For instance, if the
Field of view passes through the center of the Instrument B
Instrument be held up so that the Swivel Joint is in the position shewn by dotted lines
at G, the Eye-hole at K, and the Field of view as shewn at M, M, M, M, then the
Observer on looking through the Eye-hole K₁ cannot see the Instrument B but on
pulling the handle H to the Right the tension of the Bise Line swings the Instrument
round nearly into the position hist described Owing to friction and to the effect of
wind on the Base Line the Instrument may not perhaps be swung round accurately
into the position first described but it will be sufficient if some part of the Field of
view covers the Instrument B (or some part of the Instrument B which is taken as
a Standard point to observe to) and this can always be secured by making the Field
of view sufficiently wide and fixing the Swivel Joint G at a sufficient distance from
the Spindle F Thus no time is lost in searching for the reflected image of the
Instrument B by turning the Instrument A round by hand
The Instrument B is similarly provided with a Swivel Joint N which is placed
centrally in the Field of view by reflection V V, V, V, and to which the Base Line
1s attached by a knot or by a spring-hook The case of this Instrument is also fixed
on a spindle which turns freely in the bearings P₁ P, in the handle P which is
shewn as suitable for fixing on the muzzle Q of a rifle Consequently when the
Instruments are pulled apart by the handles to straighten the Base Line the tension
of the Base Line automatically adjusts the Instruments relatively to each other, that
1s, adjusts the Instruments so that each of them can be seen in the Field of view by
reflection of the other

page_text: If Angular Instruments on the principles of the Theodolite or Plane Table are
used they are to be fitted with Swivel Joints (for attachment of the Base Line) and
placed on Spindles in their Stands, but the automatic adjustment by the tension of
the Base Line being only approximate, while these instruments (unlike Sextints)
require to be very accurately adjusted relatively to each other, a further adjustinent
for perfect accuracy must be provided in the manner usual in these instruments
The Instruments shewn in the Drawings may be provided with telescopes for long
Ranges
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 18
1 In Range Finders consisting of two Angular Instruments connected by a Base
Line the construction of each Angular Instrument on a vertical axis round which it
can swing freely, together with the attachment of the Base Line to each Angular
Instrument (or to projecting arın on each Instrument) in such a manner that when
the Instruments are pulled apart to tighten the Base Line the Instruments are
automatically swung round into such a position that they require little or no further
adjustment relatively to the Base Line
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