IMPROVED MEANS OF AND APPARATUS FOR MEASURING OR ASCERTAINING DISTANCES
Year: 1876

page_text: LETTERS PATENT to Francis Weldon, of Windsor, in the County of Berks,
Major in the Madras Staff Corps, for the Invention of "IMPROVED MEANS OF
AND APPARATUS FOR MEASURING OR ASCERTAINING DISTANCES."
PROVISIONAL SPECIFICATION left by the said Francis Weldon at the Office
of the Commissioners of Patents on the 16th December 1876.
FRANCIS WELDON, of Windsor, in the County of Berks, Major in the Madras
Staff Corps. "IMPROVED MEANS OF AND APPARATUS FOR MEASURING OR ASCER-
TAINING DISTANCES."
This Invention consists of an instrument for measuring or ascertaining distances,
and is constructed substantially in the following manner:-To a block or piece of
suitable material is hinged or secured two limbs or arms. These limbs or arms
are jointed together by a rod or arm or rods or arms from each limb attached at or
near the ends of the said limbs, these rods or arms being held or secured at their
opposite ends to suitable arrangements between the linibs, such arrangements being
connected to a screw which passes through the block or piece before mentioned.
On the said screw is mounted and secured, at the back of the arms or rods, so as to
revolve with said screw, a cylinder or cone (or other suitable shape), on which is
marked a spiral scale; and to the limbs or arms, on the inner faces thereof, at or
near the ends farthest from the block or piece, are attached reflector sights, which
are furnished with arrangements for adjustment. When the instrument is closed
the two limbs or arms are parallel, or nearly so; the rods or armis joining same
lying between. When the instrument is being opened the screw is turned, and by
this means the rods or arms attached to the limbs force outwards the limbs to the
required angle.
The action is as follows:-At one end of a line a right angle is formed with the
distant object, and a point on that line by the instrument itself, or an optical
square. To the other end of the line the operator takes the instrument, which he
holds in his hand, and by actuating the screw with the cylinder (which action
forces out the limbs or arms), the reflected image of the right angle point on the
distant object, or vice versa, is obtained, and the distance read off from the scale

page_text: on the cylinder or cone, the distance being indicated on the said cylinder or cone
by a pointer attached to the before-mentioned block or piece, said index pointer
being fixed or adjustable as required.
The instrument can be worked with any base, the length of which can also be
determined by the instrument, and the instrument may also, when required, be
furnished with a telescope. The limbs or arms are furnished with adjusting
arrangements, so that when the instrument is closed the reflectors may be truly
parallel.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Francis Weldon in the Great Seal Patent Office on the 15th June
1877.
68
FRANCIS WELDON, of Windsor, in the County of Berks, Major in the Madras
Staff Corps. IMPROVED MEANS OF AND APPARATUS FOR MEASURING OR ASCER-
TAINING DISTANCES."
This Invention consists of an instrument for incasuring or ascertaining distances,
and is constructed substantially in the following manner:-To a block or piece of
These limbs or arms
suitable material is hinged or secured two limbs or arms.
are jointed together by a rod or arm, rods or arms, from each limb attached at or
near the ends of the said limbs, these rods or arms being held or secured at their
opposite ends to suitable arrangements between the limbs, such arrangements being
connected to a screw, which passes through the block or piece before mentioned.
On the said screw is mounted and secured, at the back of the arms or rods, so as to
revolve with the said screw, a cylinder or cone or other suitable shape, on which is
marked a spiral scale; and to the limbs or arms, on the inner faces thereof, at or
near the ends farthest from the block or piece, are attached reflector sights, which
are furnished with arrangements for adjustment. When the instrument is closed
the two limbs or arms are parallel, or nearly so, the rods or arms joining same
lying between. When the instrument is being opened the screw is turned, and by
this means the rods or arms attached to the limbs force outward the limbs to the
required angle.
The action is as follows:-At one end of a line a right angle is formed with the
distant object, and a point on that line by the instrument itself, or an optical
square. To the other end of the line the operator takes the instrument, which be
holds in his hand, and by actuating the screw with the cylinder, which action
forces out the limbs or arms, the reflected image of the right angle point on the
distant object, or vice versa, is obtained, and the distance read off from the scale on
the cylinder or cone, the distance being indicated on the said cylinder or cone by a
pointer attached to the before-mentioned block or piece, said index pointer being
fixed or adjustable as required.
The instrument can be worked with any base, the length of which can also be
determined by the instrument, and the instrument may also, when required, be
furnished with a telescope. The limbs or arms are furnished with adjusting
arrangements, so that when the instrument is closed the reflectors may be truly
parallel.

page_text: working in the collar H. The arms A, A¹, are connected with this collar H by the
bars E, E, linged to the arms A, A, at e, e¹; the screw S passes through, and is
secured to the cylinder K, which revolves with it. On this cylinder is engraved the
spiral scale, the numbers on which aro successively brought under the pointer P
by turning the screw S; this pointer P is screwed to the block B, or the same may
be adjustable. There is also on the cylinder K a scale of yards, graduated from
70 to 150, to determine the base. The right angle can be obtained by extending
the arms as far as they will go. Three pickets and a 60-feet measuring tape are
required with the instrument.
In using this instrument I proceed as follows:-The observer plants a picket
(see diagram, Fig. 6) at p, where he stands, proceeds then 40 or 50 yards to the
right, and plants a second picket 2, making a right angle with the distant
object x and the first picket p. He then measures with the tap, say, 60 feet
from the second picket p', and at that distance plants the third picket p² in a
line with the object x. These three points being fixed the observer proceeds about
100 yards to the left, turning the cylinder K as he goes, so that No. 100 on the
base scale may come under the pointer P; then placing himself in a line with the
pickets p, p, he moves backward or forward until he sees in the instrument that
the reflected image of the picket p exactly coincides with the picket p¹, thus
determining the point D, which will be 100 yards from the picket p¹. The observer
now faces the object, and turns the cylinder K until the pickets 1, 2, are both
together reflected on the object x, being careful so to place himself that the
pickets p and p' may appear in the reflectors R to be accurately aligned one on
the other. The distance of the object x is then read off the scale on the
cylinder K.
The time required by one person unassisted to find the range by the above
method need not be more than a minute and thirty seconds. The right angle is
found either by an optical square or by the instrument itself. The optical square
enables a second person to assist in taking one of the angles, by which means not
only is the range more quickly found, but the distance of moving objects can also
be ascertained.
The scale is graduated in the terms of the base, i.e., if the base be 100 yards, and
should the number indicated on the cylinder be 35, the distance would be
3,500 yards, but should the base be only 70 yards, and the number indicated on the
cylinder K be 35, as before, the distance would be 35 times 70.
The scale may be (to carry out the above) graduated on a movable cylinder, con-
centric with that shown in the Drawings, and adjustable to any length of base, and
therefore without any calculation read off the distance.
Having now particularly described and ascertained the nature and object of my
said Invention and in what manner the same is to be performed or put in practice,
I hereby declare that I claim the said Invention of "Improved Means of and
Apparatus for Measuring or Ascertaining Distances," substantially as the same is
herein-before set forth and described, and illustrated by the accompanying
Drawings.
In witness whereof, I, the said Francis Weldon, have hereunto set my hand
and seal, this Second day of May, in the year of our Lord One thousand
eight hundred and seventy-seven.
Witness,
A. C. WELDON, Bt.,
Kilmorony,
Athy,
Ireland.
F. WELDON. (L.S.)