IMPROVEMENTS IN RANGE FINDERS to be as follows:
Year: 1885

page_text: I THORSTEN NORDENFELT of 53 Parliament Street in the City of Westminster
Civil Engineer do hereby declare the nature of my invention for "IMPROVEMENTS
IN RANGE FINDERS to be as follows:-
"2
This Invention has for its object improvements in range finders.
The improved range finder takes the form of a binocular or other telescope.
It is so arranged as to give two images.
One of these images is under the control of the operator and can be brought to
coincide with the other or separated from it.
The construction is such that the separation of the images is brought about by
turning a button or milled head and a scale in connection therewith indicates the
angular separation of the images. The graduation indicates also the distance of a
floating object from the observer when the water line of the object is brought to
coincide with the horizon or it may be another water line at a known distance.
For this purpose I cut the object glass or some other of the glasses of the
telescope in two parts and move one of the balves vertically, I then obtain two
images, and by suitably moving the half glass the images may be superposed or
separated and the angular distance of one part of the image from another ascer-
tained. Or I place in the focus of the eye piece a small mirror or prism. The
half of this mirror is silvered the other half is plain glass. Near this mirror or
prism I place another mirror or prism which is moveable. When the two mirrors
or prisms are parallel I see only one image, but when I move one of these mirrors or
prisms I see a double image and the water line of an object in one image may be
brought to coincide with the horizon line in the other image or any similar com-
parison may be made. The movement can be regulated by means of a screw or a
cam, or any other suitable appliance.
A scale of distances is marked on the instrument corresponding to the angles
measured, and the height of the observers eye above the sea level.
Dated L: TOLL
CARPMAEL & Co.,
Agents for the Applicant.

page_text: I, THORSTEN NORDENFELT of 53 Parliament Street in the City of Westminster
Civil Engineer 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:-
This invention has for its object improvements in range finders.
The improved range finder takes the form of a binocular or other telescope.
It is so arranged as to give two images. One of these images is under the.
control of the operator and can be brought to coincide with the other or separated
from it.
The construction is such that the separation of the images is brought about by
the movement of a button or milled head, or drum.
A scale in connection there with indicates the angular separation of the images.
At.sea the distance of a floating object can by means of this instrument be
measured by measuring the angle made by the two lines going from the observer's
eye, one to the water line of this floating object the other to the line of the horizon
or any other water line at known distance. The images of these two lines can
easily be brought to coincide by means of the movement of one of the images in
this instrument.
The instrument may also be used to measure either on land or at sea the angle
subtended either by a known height or length. The instrument can be used for
either way of measuring distances, and for solving any other similar problem.
For this purpose I cut in half the object glass or some other of the glasses in
the telescope (in one or both tubes if a binocular) and move one of the halves
vertically or horizontally I then obtain two images and by suitably moving the
half glass the images may be superposed or separated and the angular distance of
one part of the image from another ascertained.
The instrument as I prefer to have it is represented by the annexed drawing.
Figure 1 is a side view of the complete instrument. Figure 2 is an end view of
one of the telescopes with the eye piece end unscrewed and removed.
Figure 3 is a diagram showing the arrangement of the lenses.
The instrument consists of two parallel telescopes a. a. connected by rack and
pinion gear b. b. so that the distance between the telescopes may be adjusted to
suit the eyes of the observer. The telescopes also have usual arrangements for
focussing there being a draw tube c. in each and the draw tubes are moved in and
out simultaneously by racks and pinions and a milled head c¹ on the axis of the
pinions. The two telescopes are similar in all respects. Beyond the focus of the
object glass d and lense e there is a positive lens carried by the draw tube and
divided transversely into two equal parts f¹ & f. One half is fixed and the other
half is moveable being mounted on a slide g which is moveable in a plane at right
angles to the axis of the telescope and so that the two halves fifs of the lens
remain always in contact. The slide has a projection upon it which engages with
a snail groove in the face of a disc. The two discs can be turned simultaneously
by means of a milled head h on an axis h¹ provided with worms engaging with
corresponding teeth. On the periphery of the disc is a flange i and on this are the

page_text: graduations. The graduations will be adapted to the special purpose for which
the instrument is required.
k¹ & k² are the lenses of the eye piece.
The instrument is specially adapted for ascertaining the distances of ships or
other floating bodies at sea, the measurement being made say from the bridge of
another vessel. In this case the graduations are such that when the water line
of the floating body is brought to the horizon the true distance is read. Another
scale on the same flange by preference gives the true angular distance between the
images. Similarly instruments may be graduated to give the distance from the
observer, say of a mounted man, the observation in this case being made by
bringing the head to the ground line and reading the distance from the scale.
the
I also construct range finding instruments in the following manner; I place in
eye piece a small mirror or prism. The half of this mirror is silvered the other
half is plain glass. Near this mirror or prism I place another mirror or prism
which is moveable.
m. is a
Figure 4 is a longitudinal section and Figure 5 is an end elevation of the
arrangement. k is a tube forming a part of the eye piece. 1¹³ is a mirror set in
the tube at an angle of 45 degrees to the axis, one half is silvered and the other
half is plain and transparent, or the mirror may be wholly silvered.
reflecting prism, it is mounted on pivots, and an arm m¹ is connected with it. This
arm is pressed by a spring up to a ring n which is able to turn on the exterior of
the tube . The edge of the ring is slightly inclined and by turning it a small
angular motion is given to the prism. The ring n is graduated and a zero point
is marked on the tube k. These parts are mounted in rear of the image formed
by the object glass of the telescope to which the instrument is applied and in rear
also of a lens which renders parallel the rays diverging from the image. Beyond
the mirrors I provide another lens which forms an erect image and this is viewed
by the aid of an eye lens.
When the two mirrors or prisms are parallel I see only one image but when
I move one of these mirrors or prisms I see a double image and the water line of
an object in one image may be brought to coincide with the horizon line in the
other image or any similar comparison may be made. The movement can be
regulated by means of a screw or a cam, or any other suitable appliance.
A scale of distances is marked on the instrument corresponding to the angles
measured and the height of the observer's eye above the sea level or otherwise as
already explained.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. The use in a range finding telescope for measuring angular distances, and
distances of objects on land or at sea of a lens cut in two halves and a suitably
divided scale on which the distance between two images seen in the telescope may
be read substantially as described.
2. The use of a double mirror or prisms inside a telescope for the same purpose.
3. A. binocular consisting of two parall.I telescopes each with a divided lens with
means for simultaneously moving one portion of the divided lens in each telescope
and with other adjustments substantially as described.
4. Range finding instruments substantially as described.
CARPMAEL & Co.,
Agents for the Applicant.