An Improved Range Finder.
Year: 1891

page_text: Date of Application, 5th June, 1891
Complete Specification Left, 12th Jan., 1892-Accepted, 5th Mar., 1892
PROVISIONAL SPECIFICATION.
An Improved Range Finder.
MICHAEL SNEE, Sub-Conductor and Supervisor Indian Military Works, at
present on furlough and residing in the City of Dublin, Ireland, (No. 8 Glengariff
Parade, North Circular Road) do hereby declare the nature of this invention to be
as follows:-
This instrument consists of a quadrant with a 6° sector in excess, within which
the operations of a movable sighting bar are confined. It is designed to solve the
distance from an enemy AO (when the base A, B, is known) in the right angle
triangle A B O. This base is invariably 30 yards in length or factors or multiples
thereof. The instrument being at right angles or zero, the movable or right hand
sights being laid on O, then from A the right angle B AO is laid out by the left-
hand or base sights and the base A B measured. The instrument is set up at B,
and the base sights being kept on the same alignment as at A, then the movable
sights are moved to the right by the dial screw (which turns to the left round the
dial plate at the same time) until they intersect the object at O.
The instrument is so constructed that when this intersection takes place the dial
finger or indicator points direct to the distance required.
The movement of the object sights is imparted in a certain ratio by means of
clockwork. It is mounted on a tripod stand similar to a compass and with ball and
socket arrangement. Distance between top and bottom plates is about 8", and
within which the mechanism works. The sights are folding and aligned through
split block. The radius of quadrant is about 7 inches. The dial face has a brass
lid or cover, and the instrument is carried over the shoulder in a leather case, the
stand being carried in the right hand.
Dated this and day of July 1901
M. SNEE,
Sub-Conductor.
COMPLETE SPECIFICATION.
An Improved Range Finder.
I, MICHAEL SNEE Sub-Conductor and Supervisor of Military Works, India,
at present on furlough and residing at No. 8 Glengariff Parade, North Circular
Road, in the City of Dublin, Ireland, 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 :-
My invention relates to improvements in that class of instruments generally
known as range-finders for ascertaining the range or distance of any given object
from that of the position of observation, and by the employment of the apparatus
constituting the said improvements and the simple method and means of manipu-
lating the same hereinafter explained, any person of ordinary intelligence can
determine the said range or distance, correctly and expeditiously, and, within
certain limits without any calculation whatever, hence the object of my invention.
In order that my said invention may be clearly understood, I have appended the
accompanying sheet of drawings in which
Fig. 1 is a perspective view of the apparatus as it would appear when in use.
Fig. 2 is a plan view of same.
Fig. 3 is a plan view of the apparatus as it would appear when the top plate
shewn by Fig. 2 has been removed, which also provides an internal view of the
mechanism between the sighting bar and the dial pointer.

page_text: ig. 4 is a diagram of the principle involved in the construction and working of
the instrument.
The principle upon which the said instrument shewn in the annexed drawings is
based is as follows, reference being had more particularly to Fig. 4.
The angle which the movable sighting bar describes is the angle at the object
which the base subtends, or in other words is the complement of A. B. O. and
therefore A B AO tan. 6. To obtain a direct reading as to the range or distance
of any given object the dial plate is marked off or graduated upon the basis that,
the length of the base A B being known, such divisions of the dial are adopted as
give A O directly when the base is used for different angular movements of the
sighting bar.
The markings on the inner circle, Fig. 2 are worked out upon a, 30 yards base,
for any objective distance less than 1000 yards, and the markings upon the outer
circle are computed upon a sixty yards base, and between 1000 and 2000 yards
objective distance. it being preferable to add thirty yards to the base (represented
by the line A B Fig. 4) for every additional 1000 yards, although not absolutely
necessary, but if any above sixty yards be used in connection with the instrument
shewn, it would involve some slight calculation as hereinafter described.
In carrying my invention into practice I arrange two plates E and F of any
suitable metal or other material, being sectors of a circle of about 98°, with a radius
of about seven inches, in such a manner that E is immediately above, and fitting
upon or into F, with a sufficient distance between them to contain and permit proper
working of the sighting har G, and connecting mechanism H. I. Upon the top
plate E, Fig. 2, is fixed by any suitable means, a ring J, upon which is marked,
engraved or otherwise provided, two circles, an equal distance from the inner and
outer periphery thereof. The said ring is shewn in Fig. 2 marked with divisions
of about 30, but in practice I prefer to divide the same into 360 degrees for greater
convenience in noting the range, but to avoid the crowding of the dial in the
drawings, the distances on the inner periphery of the ring are marked out at ten
yards interval from 300 to 400 yards, and at fifty yards interval from 400 to
1700 yards. The distances on the outer periphery of J are marked at 100 yards
interval throughout.
At the angle or centre from which the sector is struck is fixed a right angled
sight K, in line with the fixed sight L, and object sight M respectively, both of
which are hinged or otherwise jointed in order that they may be folded down
upon E when not in use. A pointer N is pivotted at the centre of the dial J, the
spindle of which extends downward into the plate F, and carries a pinion I,
with twelve teeth, gearing into a quadrant or portion of a wheel H, which if com-
pleted would have 720 teeth, so that while the pointer N may move completely
round the dial J, the wheel H only moves a distance equal to 6°. The said
quadrant or part of a wheel H is fixed to the bar G, as is also the sight M, and the
right angled sight K is mounted upon the same loose spindle or pivot as G, but
above E.
The under plate F is fixed upon a tripod P, provided with the ordinary swivel
movement and a clamping screw Q, which also serves as a loop for the-suspension
of a plummet R, vertically below the centre of the instrument.
To find the range or distance of any given object two men are generally
required, one to carry the instrument and stand, and the other the necessary
measuring tape and rods. The instrument is set down in any convenient spot
represented by A Fig. 4, and the pointer N.placed at the infinity point X in which
position the sights L and M are at right angles to cach other as in Fig. 2. The
operator then looks through the sights L, M, and moves the instrument on the
.swivel of the tripod, until M K is in line with the object O Fig. 4, the distance or
range of which is required. When this has been done correctly he looks through
the base sights K L, in the direction A B P Fig. 4 and directs his assistant who
has in the meantime measured off by the tape a distance of 30 yards from A, where
to plant the first rod B Fig. 4 which must be in strict aligument with the fixed base

page_text: sights KL before mentioned. The assistant then measures ont a further distance
of 30 yards from B, represented by P Fig. 4, and fixes a second rod in that spot in
strict alignment with the first rod at B, and the sights K, L. This accomplished
the operator moves the instrument from its first position at A to the position
occupied by the first rod at B, which he extracts and proceeds to place his instru-
ment in position with the plummet R vertically over the hole at B, and aligns his
fixed base sights K L, on the second rod at P, and when in this position the fixed
sight and movable sight.M would be in the direction B D Fig. 4. Now by
turning the pointer N, to the left of the infinity point X in Fig. 2, until the sight M
is in line with the object O, and noting the range pointed to by N upon the inner
periphery of J, that will be the distance in yards between B O required, as shewn
by Fig. 4.
Although the instrument as hereinbefore described is only suitable for short
distances such as would be needed for infantry purposes, it can by a slight modifi-
cation of the foregoing operations be used for artillery purposes from 500 yards
upwards without increasing the arc through which the sighting bar G moves,
by extending the working base to, say 100 yards, and if necessary a telescope
may be employed upon the movable sighting bar M for greater precision in long
ranges.
The markings on the dial J Fig. 2 are obtained from calculations upon bases of
thirty, and sixty yards, but by taking factors or multiples of these other bases can
be used, as for instance; supposing that the nature of the ground did not permit of
a base of thirty yards being measured, and the distance of the object presumably
under 800 yards, the operator would measure a base of fifteen yards, and halve the
distance indicated by the pointer on the thirty yards base ring of the dial J, and
the result will be the distance required..
Again, by using a base of ninety yards, and multiplying by three the distance
indicated by the pointer N upon the thirty yards base, the instrument can be used
for artillery purposes up to a distance of 5100 yards, a distance beyond which it is
seldom requisite to measure. A suitable book, card or pamphlet containing tables
of calculations upon the foregoing principle for bases of various lengths may be
provided with each instrument, and the whole contained in a suitable case, or cover,
furnished with a strap handle or the like by which it may be carried.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed declare that what I
claim is.
1st. In a new or improved range finder the construction and use of the apparatus,
and the several parts constituting the same as herein described and shewn, con-
nected, combined and operating in the manner set forth, substantially as and for
the purposes specified, and shewn by the accompanying drawings.
2nd. In a new or improved range finder the employment of two quadrantal plates E
and F, placed and fixed one above the other, so that a space exists between them,
the former provided with a suitably divided dial plate J with a 6° sector in excess
folding fixed sight L, right angled sight K, and movable pointer N, mounted upon
a vertical spindle or pivot extending through E into F, and carrying a pinion I,
situated between E and F, in gear with a toothed quadrant H, fixed to and upon a
novable bar G, carrying a folding sight M, the whole combined and operating
substantially as and for the purposes described and shewn by the appended
drawings.
Dated this 11th day of January 1005
GEO. THOS. HYDE,
4, Moorfields, Fore Street, London, E.C.