Range-finder for Telescopes, Field and Opera Glasses, and the like.
Year: 1888

page_text: Date of Application, 24th Aug., 1888
Complete Specification Left. 23rd May, 1889-Accepted. 13th July, 1889
PROVISIONAL SPECIFICATION.
Range-finder for Telescopes, Field and Opera Glasses, and the like.
CONSTANT ROBERTS VAN SON of II Schüttelstrasse 17, Vienna Austria, Gentleman
do hereby declare the nature of this invention to be as follows :-
manner.
The object of this invention is the application of a simple device to Telescopes Field
and Opera Glasses, etc. by means of which moderate distances may be estimated
quickly and with tolerable exactness. This device is of special importance in shooting,
and bases upon the principle, that objects at different distances appear of different
size, the object seeming the smaller, the further it is from the eye. Basing upon
this principle 1 fix a scale either before or behind the objective of a Telescope,
Field Glass etc. either in a horizontal or a vertical position, which scale is divided
into graduation, the distance between which is fixed by observation in the following
that
The Telescope or other Glass is held at such distance from the eye
the object whose distance from the eye is to measured is visible as well as the
scale in or before the glass. The object looked at must be of a known proportion,
(length or hight). Supposing a rod of one half yard in length is in this manner
observed at a given distance of 25 yards, the length of the scale is so fixed that
it will just cover the rod, when the latter is observed through the glass in the
manner before indicated. If the same rod be now removed to a distance of 50 yards
from the eye, it will appear to cover but one half of the scale in the glass; at one
hundred yards it will cover but one fourth of the scale and so forth. According
to these observations, the scale is graduated into a certain number of degrees,
16 for instance. The rod of one half yard will consequently at a distance of
100 yards cover degrees
200
300
4
"
":
"
"
""
2*
and so forth.
27
As
The scale being thus graduated, the distance of objects of approximately known
proportions, such as animals etc. may be measured by comparing them with the scale
in the glass in the manner before described. The eventual mistake in estimating
moderate distances in this manner does not amount to more than ten per cent. of
the distance measured, which in shooting for instance is of no consequence.
before mentioned the scale may be placed before or behind the objective in the
glass. The scale may be made of any transparent or non-transparent material and
If the scale is
may be attached to the glass or objective in any desired manner.
not transparent the graduations must of course be on the side facing the eye.
The scale or its graduations may also be graved, ground, or etched
the
objective.
Although the scale is not, or but very slightly, visible when the glass is held
to the eye as usual, it may be made to slide or turn out of sight when not in use.
aul Aument 1008
upon

page_text: COMPLETE SPECIFICATION.
Range-finder for Telescopes, Field and Opera-glasses, and the like.
CONSTANT ROBERTS VAN SON, No. 17 Schuttelstrasse, Vienna, Austria, Genileman,
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 this invention is the application of a simple device to telescopes. field
and opera-glasses etc., by means of which moderate distances may be estimated quickly
and with tolerable exactness.
This device is of special importance in shooting and bases upon the principle,
that objects at different distances appear of different size, the object seeming the
smaller, the furthere it is from the eye. Basing upon this principle, I fix a scale
either before or preferrably behind the objective glass of a telescope, field glass etc.
either in a horizontal or à vertical position.
This scale is divided into graduations, the distance between which is fixed by
observation in the following manner: The field or other glass is held at such distance
from the eye, that the object, whose distance from the observer is to be measured is
visible as well as the scale in or before the glass. The object looked at must, for
graduating the scale be of a known proportion (length, width or height). Supposing
a rod of one half yard in length is in this manner observed at a given distance of
25 yards, the length of the scale is so fixed, that it will just appear to cover the
rod, the glass being held a certain distance from the eye as before indicated.
If the same rod be now removed to a distance of 50 yards from the eye, it will
appear to cover but half of the scale in the glass, at 100 yards it will appear to
cover but one fourth of the scale and so forth.
In the annexed drawing a glass provided with such a scale is shown.
Figure 1. represents a glass with a fixed scale.
Figure 2, 3 and 4, show a scale which may be turned into or out of sight.
The scale a. thus shown is according to the above observations divided into a
certain number of degrees, in this case 16 for instance. An object of a known length
of one half yard will consequently at a distance of:

page_text: For this purpose the scale a. may be made to turn upon its axis b. to the top, bottom,
side or interior of the glass by an outside knob or button.
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 device for measuring distances, formed by fixing a scale behind or in front
of the objective of a telescope, field glass, opera-glass or the like, which scale will
become visible simultaneously with the object observed, when the glass is held at
a certain distance from the eye; the distance to be measured fixed by comparing
the dimension of the object with the scale in the glass; substantially as herein
described.
2. In range finders of the kind described in claim 1, a scale which is so arranged,
that it may be turned out of sight when not in use; substantially as described.
Dated this 3rd day of Nov 1880
E. EATON & Co.,
Agents for Applicant.