An Improved Method of and Apparatus for Range Finding.
Year: 1888

page_text: COMPLETE SPECIFICATION.
An Improved Method of and Apparatus for Range Finding.
I, CHARLES ANNESLEY BENSON of Ormonde House, Sion Hill; Bath Major General
of the Madras Infantry 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 stateinent :-
1. Guiding Bars Two parallel Guiding Bars A A¹ Figs. 1 & 2 Twenty seven
inches in length one inch in breadth and one and a quarter inch in thickness are
framed two inches apart by the insertion of blocks B, B, two inches square at each end,
and preserved from warping by intermedial blocks and binders C, Fig. 1. The frame
has a horizontal axis. The axles at each end work through small holes D Fig. 3,
pierced in the centres of two flat uprights E quarter inch thick six inches high and
four inches broard at four and a quarter inches from their bottoms which are flat, the
remainder rounded off. The uprights E, E¹, Figs. 1. 2. 3. are connected at the bottom
by a third bar F one inch thick and one and a quarter inch broad. The third bar F.
Figs. 1. 2. 3 has a central plate G, Figs. 1. 2. 3 eight inches in diameter which when in
use rests with a vertical axis on a tripod topped by a circular table H nine inches in
diameter. Clamping screws L, L, 1, 1, Fig. 1. 2. 3 fix the frame and bar in the
required positions.
N.B. The above thicknesses are applicable to a wooden structure. If in metal they
may consistent with strength be considerably reduced in proportion.
2. Guiding Bar Telescope-At one end of the Guiding Bars A, A', Fig. 1. 2 on
the block B between them is placed a Telescope J (with cross wires) 10 inches in
length with 1 inch diameter sunk up to its centre in a bar K 84 inches long
and 1 inch square with a vertical axis which is fixed by a clamping screw L at an
acute angle the magnitude of which is determined by the proportion required between
length of base and distance to be measured.
3. The Pilot-The Pilot consists of two tubes M, N, Fig. 10. 11. which meet at, a
right angle. At their junction is a diagonal upright mirror O at an angle of 45 degrees
to each. The mirror which is 1 inch high and 1 inch broard slides into the face of
a small block P of equal height sunk to the depth. of 3 inch, in a Board Q which
:

page_text: carries the tubes M, N. The block P, Fig. 10 slides in and out, a screw however
is used to keep it steady. A box R, Fig. 11, 14, 21 inches square covers the block P,
Fig. 10 and adjacent portions of the tubes M, N to exclude all light other than that
passing through the tubes. The sides S of the box R sink into the Board Q-Cross
wires T are placed in the mouth of one of the tubes N half an inch from the centre of
the mirror O. This tube N Fig. 10, which lies direct between the mirror O and side
of the Board U' is 34 inches in length and 1 inch in diameter. To obtain near yet
distinct vision of the cross wires T without the need of adjustment a pin hole V,
Fig. 10. 11. 13 is employed in the eye piece W of the other tube M which is telescopic
for other purposes. The Board Q Fig. 10, 11 in which the tubes M, N, as well as the
mirror are embedded is 14 inch thick 10 inches long and 8 inches broad. The
centre of the mirror O is 6 inches from the front X 4 inches from each side U
and 4 inches from the back Y of the Board. The pin hole V in the eye piece W
the horizontal wire of the cross T and the centre of the mirror Olie in a level
with the surface of the Board Q. For persons whose sight is defective a glass Z
Fig. 13 can be inserted at the eye piece W and if required another glass in the
end U¹ of the further tube N. Fig. 10.
It is moved
4. The Binocular-A portion of the Board Q carrying the Pilot 2 inches in
breadth is reduced to the thickness of half an inch from the bottom. On this
part al Fig. 10. 11. 12 lies a bar 618 inches long 18 inch broad and 1 inch high
in which is sunk up to its centre a Telescope C¹ (similar to the Guiding Bar Tele-
scope c) which is placed for convenience as near as possible to the inner edge of
the bar 6. This Telescope lies parallel with the Pilot tube M. Fig. 10. 11. con-
taining the eye piece W and is cut perpendicularly at 44 inches from its object
glass d¹ Fig. 10. 12. by the prolongation of a line passing through the centre of
the tube N. Fig. 10 holding the cross wires, T. The lines of collimation of the
Telescope c and Pilot M, N Fig. 10 are in the same horizontal plane. The
Telescope c¹ has a parallel movement to adapt the distance between its eye piece e¹
and that of the Pilot W to the distance between the eyes of the measurer.
in a lateral direction by means of a slow motion screw f1, Fig. 10. 11. 12 attached to
its bar b working through a small block g¹ on the edge of the Board a¹. A couple of
tenons ¹. Fig. 12 inch broad and inch thick are fixed each 2 inches from
the centre across the portion of the Board a¹ which supports the bar ¹, on these
mortises ¹, across the bottom of the bar 61 slide to prevent any irregular
movement. A block J Fig. 11. 12 6 inches long 11 inch deep and 2 inches broad
is fixed lengthways across the bottom of the Board Qa¹ so that a central line from
end to end lies directly beneath the vertical wire T of the Pilot N Fig. 10. This
block J¹ fits firmly and squarely between the Guiding Bars A A¹ but is removable
at pleasure. When the Binocular Qa¹ is on the Guiding Bars A, A¹ a line from
the centre of the mirror () through the centre of the cross wires T of the Pilot N
produced bisects perpendicularly the vertical axis of the Guiding Bar Telescope J.
The Telescopes J & C and Pilot M, N, are bridged K' K¹ K' K' over to keep them
in their grooves L' Fig. 1. 2. 10. 11. 12.
5. Guiding Plates-Two Guiding Plates m¹ n¹ Fig. 1, 2 and to 7 are mounted on
the Guiding Bars A A¹, Fig. 1. 2. 3 one at each end. Each rests on a block o' two
inches broad which fits firmly and squarely between the Guiding Bars A A. They are
however removable for packing up. One Guiding Plate m¹ Fig. 5 has a central
vertical line p¹ the other n¹ Fig. 7 a central vertical line p' and a horizontal line, q.
The former plate m¹ is 12 inches high and 6 inches broad the latter n¹ 6 inches high
and 12 broad. The higher one m is placed near the Guiding Bar Telescope J,
Fig. 1. 2. 3. The lines face the end of the Guiding Bars furthest from the Telescope J.
Fig. 1. 2. 3. When the Binocular Qa¹ is on the Guiding Bars A A' the horizontal
line 9 of the Guiding Plate n' is in the same plane as the surface of the Board Q,
the horizontal wire T of the Pilot N and the lines of collimation of the two Tele-
scopes J, C. To mark the lines distinctly the Plates are colored. The colors differ
on each side of the vertical line p¹, Fig. 3. 5. 7. These colors as they appear on one
Plate are reversed on the other. On the lower Guiding Plate n Fig. 1. 2. 3. 7 which

page_text: is furthest from the Guiding Bar Telescope J different colors in order to distinguish
them from those above are used for the parts below the horizontal line q¹. The
Guiding Plates m³ n', Fig. 1. 2. 3. being attached to the Guiding Bars A A¹ rotate
vertically and horizontally with them and thus their lines indicate the plane in which
the line of collimation of the Guiding Bar Telescope J lies as well as the direction of
the Base line. The lines p', q' Fig. 3 on the Guiding Plates m² n¹ are viewed by the
Measurer through the Pilot M. N. Fig. 10. 11 when moving to a flank. The vertical
lines p¹ p¹ of the two Plates m³, n' are kept in line with each other.
6. Guiding Rods When the proportion of Base to distance is more than half an
inch to the yard and the object is far off, or in any case, when the Base Ground
slopes, a Guiding Rods r, s, Fig. 1. 2. 3. 8 is attached below each end of the Guiding
Bars A A' and is constructed in this wise.. Three pieces of wood each one inch square
are joined together so as to form three sides 5 × 4 inches inside-The ends of the two
pieces 5 inches in length are attached to the top of the Guiding Bars A A¹ by small
bars tt. A rod one inch square is fitted to the bottom of the square. One Rod s¹
is 3 feet long the other r¹ 4 feet and one s³ is colored white and the other r² red. They
swing with the Guiding Bars. The longer Rod is near the Guiding Bar Telescope J.
When in use the Guiding Rods s₁₁are kept in line with each other as are the lines
on the Guiding Plates m¹n¹ Fig. 3.
7. Plummets An ordinary plummet may be used to indicate on the ground the
position of the axis of the Guiding Bar Telescope J. The plummet line u¹ Fig. 2
fastened below the axis falls through a hole v¹ in the lower bar F. This also aids in
placing the Guiding Bars A A¹ horizontally when setting up the Tripod. A sugar
loaf plummet w¹ is employed to mark the spot where the right angle of the triangle
occurs. This plummet is attached to the centre of the bottom of the bar b¹ of the
Telescope C¹ of the Binocular Qa¹ 4 inches from its object glass d¹ and falls
through an aperture X' in the Board a¹ and bar J¹ beneath in the same plane as
the vertical wire T of the Pilot N Fig. 10. 11. 12. An ordinary plummet Z
Fig. 2. 3. is referred to in paragragh 11.
8. Tape A winding Tape marked in feet inches and half inches may be used for
measuring the Base. The ring is fixed by a peg in the ground beneath the Guiding
Bar plummet u¹ Fig. 2.
9. Roller A Roller y¹ Fig. 9 about three inches long revolving in a forked peg
is stuck in the ground in the line of the Base beneath the end of the Guiding
Bars A A¹ nearest the Measurer. Under this the Tape is drawn to prevent inter-
ference with the legs of the Tripod and the Guiding Rods ¹¹ when the Measurer
moves out with it and the Binocular Qa¹.
10. The Base-The Base to be measured, the length of which indicates the distance
of the object, is the line between the axis of the Guiding Bar Telescope J and the
spot where the Measurer finds by the Binocular Qa¹ (which is carried in the
hand) that that line and the line from the distant object meet at a right angle in
the same plane that is when the horizontal wire T of the Pilot M N coincides with
the horizontal line q¹ of the nearest Guiding Plate n¹ and the vertical wire T
of the Pilot M N coincides with the vertical lines p' p' on both Guiding Plates m¹ n'
and the Guiding Rods while the vertical wire of the Telescope c¹ concides with a
vertical edge of the object.
11. To set the Acute angle (para. 2). The Guiding. Bar Telescope J can be set by
the Measurer at the required angle at any time prior to using the apparatus. The
procedure.is as follows. Select an object with a sharp vertical edge (A Guiding
Rod suspended vertically from a bough of a tree will answer the purpose) and
measure therefrom 6, 12, 24 or 48 yards according to whether the Base is required to
be 2 inches 1 inch inch or inch to each yard of distance. At the end of the length
measured place the centre of the Tripod from which a plummet Z¹ Fig. 2. 3, has been
suspended. Place the Binocular Qa¹ on the Guiding Bars A A¹ so that the centre of
the Telescope is exactly over the twelfth inch from the axis of the Guiding Bar
Telescope J. (The Guiding Bars are marked for the purpose). Turn the Guiding
Bars A A¹ so that the vertical wire of the Telescopic c' of the Binocular Qa¹ cuts the

page_text: edge of the object and clamp. Then turn the Guiding Bar Telescope J till its vertical
wire also cuts the edge of the object and clamp. The angle once set should not be.
interfered with except for purposed alteration or verification.
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. That a Pinhole in the eye piece of one of two tubes meeting at an angle in
concert with cross wires in the other and a covered mirror at the junction of the tubes.
constituting "The Pilot" is a novelty.
2. That the combination of "The Pilot" and Telescope used binocularly is a novelty.
3. That Guiding Plates with colored cross lines and Guiding Rods rotating with.
Guiding Bars to denote the lie of a Base and the plane of a Triangle is a novelty.
Dated this 18th day of December 1888.
C. ANNESLEY BENSON,
Major General, Madras Infantry.