IMPROVEMENTS IN APPARATUS FOR ASCERTAINING DISTANCES
Year: 1871

page_text: LETTERS PATENT to John Stephens, of Duke Street, in the County
of Middlesex, for the Invention of "IMPROVEMENTS IN APPARATUS FOR
ASCERTAINING DISTANCES."
Scaled the 23rd January 1872, and dated the 28th July 1871.
PROVISIONAL SPECIFICATION left by the said John Stephens at the
Office of the Commissioners of Patents, with his Petition, on the
28th July 1871.
I, JOHN STEPHENS, of Duke Street, in the County of Middlesex, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
APPARATUS FOR ASCERTAINING DISTANCES," to be as follows:-
:-
These improvements relate to apparatus for ascertaining distances at
sea and on land, and are applicable for military, naval, engineering, and
other purposes.
The apparatus consists mainly of two telescopes mounted upon a base
plate, which is pivotted upon a tripod or other stand so that it can be
turned into any position and there fixed by a thumbscrew. One of the
telescopes is firmly attached to the base plate, and the other is free to be

page_text: turned on a pivot to bring its line of sight in line with the object, which
has previously been selected by an attendant looking through the fixed
telescope, the pivotted telescope being mounted upon a quadrant shaped
plate which moves with it. The outer edge of the quadrant shaped
plate gears into or against an index finger or pointer, which is caused to
travel over a ring scale divided into miles, furlongs, yards, or other
divisions or subdivisions of distances for indicating the distance of the
object from a given point. Where minute divisions or subdivisions of
distances are required multiplying gearing would be employed to move
the index hand or hands in conjunction with the quadrant plate and
pivotted telescope.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Stephens in the Great Seal Patent Office on
the 27th January 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
STEPHENS, of Duke Street, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of July, in the year
of our Lord One thousand eight hundred and seventy-one, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Stephens, Her special licence
that I, the said John Stephens, my executors, administrators, and assigns,
or such others as I, the said John Stephens, my executors, adminis-
trators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN APPARATUS
FOR ASCERTAINING DISTANCES," upon the condition (amongst others) that I,
the said John Stephens, my executors or administrators, by an instru-
ment in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, and cause the
same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.

page_text: NOW KNOW YE, that I, the said John Stephens, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement thereof, reference being had to the Drawings here-
unto annexed, that is to say :-
These improvements relate to apparatus for ascertaining distances at
sea and on land, and is applicable for military, naval, engineering, and
other purposes, as will be gathered by the following description with
reference to the Drawings annexed :—
The apparatus shown in Figures 1 and 2 consists mainly of two
telescopes a, b, mounted upon a base plate c, which is pivotted upon a
tripod or other stand d, so that it can be turned into any position, and
there be fixed by a thumbscrew e. The telescope a is firmly attached to
the base plate c, and the other b is free to be turned on a pivot f to
bring its line of sight in line with the object, which has previously been
selected by an attendant looking through the fixed telescope a, the
pivotted telescope 6 being mounted upon or attached to a quadrant
shaped plate g, or its equivalent, which moves with it. The outer edge
of the quadrant shaped plate g gears into or against an index finger or
pointer h, which is caused to travel over a ring scale i, divided into
miles, furlongs, yards, or other divisions or subdivisions of distances for
indicating the distance of the object from a given point. Where minute
divisions or subdivisions of distances are required, multiplying gearing
could be employed to move the index hand or hands in conjunction with
the quadrant plate and the pivotted telescope. The distances the two
telescopes are arranged apart are determined by the divisions upon the
scale, consequently they would vary according to the purposes for which
the apparatus is intended.
The method of taking the distance of any given object will be clearly
understood by referring to the Diagram shown in Figure 3, where the
object within sight of the fixed telescope a is shown to be, say, 2000
yards off, the movable telescope 6 having been turned upon its pivot to
bring its line of sight upon the object spotted by the observer through
the telescope a, this motion of the telescope b having caused the index
finger or pointer to travel over the scale, and from which the distance
can be read with freedom.
In this first method I arrange a rubber band j upon the stem k of the
pointer, which band bears against the edge of the quadrant shaped

page_text: plate g, so that it partakes of the necessary motion, but any means of
causing the finger to move may be adopted as found desirable, adjustable
screws 1, 1, being arranged upon the tripod to enable the attendant to
adjust the base plate with the horizon, or at an angle thereto.
Figure 4 shows a distance indicator fitted with toothed wheels m, m,
which derive their motion through the pinions o, p, gearing respectively
into teeth q, r, s, on the edge of the quadrant plate g, each pinion and
each set of teeth being of different pitch, in order to regulate the move-
ment of the finger h for the varying angles which the movable telescope
assumes between, say, the 100 yards range and the 2000 yards range, as
shown in the Diagram, Figure 3.
In the foregoing I have shewn a circular or ring scale, but a segment
of a circle, or several segments of circles can be employed for the finger
to travel over; one example of this is shown in Figure 5, where the
finger his attached to the movable telescope b, slots being formed in the
shank for the division lines to be seen, the scale being so arranged on
the three arms or segments t, u, v, that the short distances, say, from 50
to 200 yards, could be read off the arm through the slot w, and then
the distances from 200 yards to 500 yards would be read off the arm u
through the slot x formed in the shank, and the distances between the
500 yards and the 2000 yards could be read off the arm v from the tip
of the finger h.
I have referred to the above as employing one finger only, but by a
rearrangement of the scale arms three fingers could be used, each finger
serving for its own arm, which is divided according to the length of the
base plate, or the distance the two telescopes are apart. In this case
the skill and judgment of the operator as to the distance of the object
from his standing place would be necessary, the fingers being provided
with pins and slot holes, along which the pins could be moved, so that
one finger would travel with the other, that is to say, should the distance
of the object be judged at about 350 yards, the attendant would lock,
say, the small finger with the middle finger, so that they both would
move together. Again, should the distance of the object be judged at
about 800 yards, he would lock the middle finger with the longest
finger, so that the three would move together, the reading being taken
off in each case the arm to which the finger belonged; this plan would
enable me to mark off the lines very clearly, consequent through the

page_text: sight lines being closer one to the other as the distances of the objects
increase.
Another method of actuating the finger from the quadrant shaped
plate is shewn in Figures 6 and 7; here a cord y from the plate 9 is
passed round a spirally grooved disc z, in which a spring is fitted, to
return it to its normal condition, that is, with the finger tip at zero, so
that the least motion of the pivotted telescope and the quadrant shaped
plate is caused to actuate the finger, the scale being first divided into
divisions of, say, 10 yards, and in proportion to the action of the spiral
disc upon the finger. The cord y is guided by the roller a', which is
adjustable, to maintain the requisite tension upon it to keep it in the
spiral groove.
And having now described the nature of my said Invention, and in
what manner the same is to be performed, I declare that I claim,-
Firstly. The construction and employment of apparatus for ascer-
taining distances, substantially in the manner described and shewn in
Figures 1 and 2 of the accompanying Drawings.
Secondly. I claim the modifications of the apparatus shown in Figures
4, 5, 6, and 7, and their method of action, for the purposes set forth.
In witness whereof, I, the said John Stephens, have hereunto set
my hand and seal, this Twenty-fifth day of January One thousand
eight hundred and seventy-two.