Improvements in Apparatus for Measuring or Ascertaining Distances.
Year: 1888

page_text: Date of Application, 17th Sept., 1888
Complete Specification Left, 16th July, 1889-Accepted, 17th Sept., 1889
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Measuring or Ascertaining
Distances.
I FRANCIS WELDON, a Colonel in the Madras Staff Corps, residing at Erlimount,
Earley, near Reading, in the County of Berks, do hereby declare the nature of this
Invention to be as follows:-
The object of my invention is to effect certain improvements in the range-finder
or instrument for measuring and ascertaining distances by means of prisms cut to
reflect certain required angles, for which Letters Patent were granted to me bearing
date 24th May 1883 and numbered 2589.
According to my present invention I secure the said prisms on an axis or spindle
around which they can revolve and this axis is attached to a telescope, in such manner
that each prism, as required, may be brought in turn in front of the object glass of
the telescope by rotation on the axis, while a slight tilting motion is also provided
as an additional means of adjustment. On looking through the telescope an object
to the right (or left) of the observer will be seen through the telescope, by reflection
from a prism, together with an object viewed in front, by direct vision through
the telescope, and the distance can be ascertained in the same manner as described
in my aforesaid Letters Patent No. 2589 of 1883.
A similar arrangement can be applied to binocular glasses if desired. .
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AMBROSE MYALL,
21, Cockspur Street, S.W., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Measuring or Ascertaining
Distances.
I, FRANCIS WELDON, a Colonel in the Madras Staff Corps, residing at Erlimount,
Earley, near Reading, in the County of Berks, 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 :-
The object of my invention is to effect certain improvements in the range-finder
or instrument for measuring and ascertaining distances by means of prisms cut to
reflect certain required angles, for which Letters Patent were granted to me, bearing
date 24th May 1883, and numbered 2589.
In the accompanying sheet of drawings, Fig. 1 is a side elevation, and Fig. 2
a plan of my improved instrument, in position ready for use: Fig. 3 is a side
elevation shewing the instrument closed.
Similar letters of reference denote similar parts throughout the drawings.
The prisms A, B, C, D, which are cut to reflect certain required angles, are
mounted in a frame E capable of rotation around the spindle F. This spindle is
mounted and capable of rotation on a stud H, affixed to the side of a small
telescope J, and the telescope is held by, and is capable of revolution within a
ring K on the end of a handle L. When the spindle F is placed parallel or
thereabouts with the axis of the telescope, as shewn in Figs. 1 and 2, each prism,
as required, may be brought in turn in front of the object glass of the telescope by
rotation on the said spindle. On looking through the telescope, an object to the
right or left of the observer, according to the side to which the prisms have been
turned, will be seen through the telescope by reflection from a prism, together with

page_text: an object in front viewed by direct vision through the telescope, and the distance
can be ascertained in the same manner as described in my aforesaid Letters Patent
No. 2589 of 1883.
As the telescope with the prisms attached, can be rotated within the ring K, and
the spindle F can be moved about the stud H, the combination of these motions gives
the power of placing the prisms in any desired position, relative to the axis of the
telescope, above, below, or on either side of the said axis. When not in use the
prisms may conveniently be turned down, as shown in Fig. 3, and to make
the instrument still more compact, the ring K is formed with a stud entering the
handle L and secured by the screw M, so that by slackening this screw the handle can
be removed.
In the instrument shewn in the drawings, four prisms A, B, C, D, are employed;
A is cut to reflect an angle of 90°, and B C and D are cut to reflect such angles
that they will, in combination respectively with A, give bases measuring one fiftieth,
one twentieth, and one quarter of the range, but I do not confine myself to the
employment of this particular number of prisms, nor to the angles or proportions of
bases described.
Similar arrangements of prisms may be applied to binocular glasses, as well as to
a single telescope, if desired.
Instruments constructed in accordance with my invention, although primarily
intended as range-finders, also form effective and reliable instruments for general
surveying purposes.
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. A range-finder or instrument for measuring and ascertaining distances, con-
sisting of the combination of prisms, cut to reflect certain required angles, with a
telescope in such manner that the said prisms can be placed in any required
position relative to the axis of the said telescope and each prism be brought in turn
in front of the object glass thereof, substantially as herein set forth.
2. A range-finder or instrument for measuring or ascertaining distances, consisting
of the combination of prisms, ent to reflect certain required angles, with a pair of
telescopes placed at an angle to each other and having a common eye-piece,
substantially as herein set forth.
3. A range-finder or instrument for measuring and ascertaining distances,
constructed substantially as herein described and shewn with reference to the
accompanying drawings.
Dated this 16th day of T、l. 1980
AMBROSE MYALL,
21, Cockspur Street, London, S.W., Agent for the Applicant.