Improvements in Telemeters or Range Finders.
Year: 1888

page_text: Date of Application, 8th Sept., 1888
Complete Specification Left, 8th July, 1889-Accepted, 7th Sept., 1889.
PROVISIONAL SPECIFICATION.
Improvements in Telemeters or Range Finders.
I, EDMUND LYONS WELLESLEY HASKETT-SMITH, of 6 Queen Anne's Gate, in
the City of Westminster, Civil Engineer, do hereby declare the nature of this
Invention to be as follows :-
The object of my Invention is to provide a telemeter or range finder by which
the distance of objects from the observer can be found expeditiously and with
practical accuracy by direct indications on scales carried by the instrument so as
to obviate the necessity for calculation or reference to tables of tangents. It also
presents the advantage of the observation being made by means of two telescopes
to which the observer applies his eyes at in using an ordinary binocular glass.
According to my Invention I provide a perpendicular base consisting of a tube
having at its upper end a prism and at its lower end means for securing it in position
as for example a spike for fixing it in the ground. In this tube at a suitable
distance from the ground is an object glass and below this is the other prism to
deflect the image into an eye piece, at right angles to the base, this forms one
telescope and at the side of this is another eye piece and object glass constituting
another telescope so that there is a telescope for each eye of the observer. This last
named telescope is for direct observation and it is centered so that it can be turned
through an angle in a plane parallel with the base formed by the tube. It is by the
extent of angular movement which is given to this telescope to bring about coincidence
of the image of the same object observed by both eyes that the distance is
measured.
To give the distance with great exactitude and facility I provide two scales one
of which indicates say hundreds of yards and the other say yards in each of such
hundreds.
For this purpose I secure to the base a bracket in which there is a double slide
the first member of which can be moved by a screw in one direction and the second
member of which can be moved by another screw in a direction at right angles to
the direction of movement of the first member. The second member is carried by,
and is adjustable in, the first member. The screw which gives movement to the first
member is provided with a disc having a spiral groove on its face in which works a
pointer guided on any suitable fixed guide bar. A rod is connected to the direct
observation telescope and this rod has on it a projection which is kept in contact
with an inclined piece carried by the second member as herein after explained. When
the screw which works the first member is operated the arm connected to the direct
observation telescope is moved so that the said telescope has its angular position altered
to a degree in accordance with the extent of movement of the screw and so that when
the two telescopes are parallel the pointer is in the outermost convolution of the spiral
groove in the disc and when the direct observation telescope is at its greatest
angular position relatively to the fixed telescope the pointer is in the innermost con-
volution of the spiral. As in the former case the instrument is in the position of
infinity and in the latter case the instrument is in position for observing objects at
the least distance for which the instrument is adapted it follows that I can mark a
scale on the spiral of the disc showing approximately (say in hundreds of yards) the
distance of the object observed when its images received by the two telescopes coincide.
In order to make a practically accurate subdivision (into say yards) of these indica-
tions of hundreds of yards the inclined surface before named is used. It is carried by
the second member so that it can by means of a micrometer screw be adjusted in a
plane at right angles to the movement of the first member. This inclined surface on
being traversed will cause the projection (from the rod of the moveable telescope) to

page_text: be moved and consequently the said telescope also to be moved to an extent in
accordance with the angle to which the said piece is adjusted. As the extent of
movement of the telescope for obtaining the exact adjustment for coincidence of the
images as seen by both eyes varies in an inverse ratio to the distance of the object
observed I alter the angle of the said inclined piece in accordance with the distance
in say hundreds of yards to which the instrument is adjusted by the spiral groove
before named. This I effect by connecting the said inclined piece to a part which is
centered to the first member so that it moves therewith when the first member is
adjusted and there is a cam piece on the centered part so shaped as to give the
increased movement necessary when the first member is adjusted for the shorter
distances. This cam piece bears on a fixed part so that it compels the hinged piece
to move to the necessary extent to give the necessary inclination to the inclined piece.
There is thus in taking an observation a first adjustment indicated by the spirally
grooved disc and obtained by the movement of the first member tilting the moveable
telescope and during this adjustment the cam and hinged piece have caused an
angular movement of the inclined piece to an extent corresponding to the distance in
hundreds of yards to which the instrument is adjusted.
By now working the micrometer screw of the second member the inclined piece is
traversed and by reason of its angular surface bearing on the projection from the
telescope arm that arm further tilts the moveable telescope to an extent for each yard
in accordance with the hundreds of yards to which the instrument has been set by
the movement of the first member. The micrometer screw or any suitable one of the
longitudinally moveable parts of the second member is provided with a scale say of
yards by which the extent of movement necessary to present the images of the object
in a coincident position at each telescope can be ascertained and so the degree of
movement imparted to the said inclined piece gives a more precise indication of the
distance of the object observed.
The instrument is capable of use in land or marine service. For example the
tubular metal masts of vessels may be used as a base provided that the telescopes are
in convenient position for the user and so reliable indications of range can be obtained
on shipboard.
COMPLETE SPECIFICATION.
Improvements in Telemeters or Range Finders.
I, EDMUND LYONS WELLESLEY HASKETT-SMITH of 6 Queen Anne's Gate 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 :-
The object of my Invention is to provide a telemeter or range finder by which the
distance of objects from the observer can be found expeditiously and with practical
accuracy by direct indications on scales carried by the instrument so as to obviate the
necessity for calculation or reference to tables of tangents. It also presents the
advantage of the observation being made by two telescopes to which the observer applies
his eyes as in using an ordinary binocular glass.
I will describe my Invention with reference to the accompanying Drawings..
Figures 1 and 2 of which shew in views at right angles to each other the
complete instrument. Figure 34 is a plan of the telescopes. Figures 1, 2, 3 and 4
are respectively a top plan, bottom plan, elevation and vertical section of the top
prism or reflector and its box. Figures 5 to 8 are similar views of the ring fixed to
the tubular base and having therein holes to receive bayonet points as supports for
the instrument when in use. Figure 9 is a side elevation and Figure 10 a section of
the mechanism for effecting adjustment. and measuring the angle of adjustment.
Figure 10 is a section on the line 1-2 Figure 10. Figures 11 and 12 are side and
end elevations of a modification of the same. Figure 13 shews part of the tubular

page_text: base with the fixed telescope and lower reflector or prism. Figures 14 and 15 show
the bracket fixed to the tubular base and carrying the moveable telescope. and.
Figure 16 shows the adjustable telescope.
According to my invention I provide a base consisting of a tube A (which may be
a single tube or be made telescopic for giving a long, base in use with compactness
for transport). This tube has at its upper end an opening opposite which is a.
prism a (Figure 4) and at its lower end means for securing it in position as. for
example a spike a¹ for fixing it in the ground. It may further be supported by means
of bayonets on rifles the points of the bayonets being inserted into holes in the ring at.
In the tube A at a suitable distance from the ground is an object glass a Fig. 13"
and below this is the other prism a³ (convex at the side presented upwards and concave
at the side presented towards the telescope B) to deflect the image into an eye piece
at right angles to the base this forms one telescope B and at the side of this is
another eye piece and object glass constituting another telescope C parallel to the
telescope B so that there is a telescope for each eye of the observer. This last named
telescope is for direct observation and it is centered at c in bearings in a bracket c
secured to the tube A so that the said telescope can be turned through an angle in
a plane parallel with the base formed by the tube A. It is by the extent of.angular.
movement which is given to this telescope to bring about coincidence of the
images of the same object observed by both eyes that the distance is measured.
The telescope C is provided with a sliding adjustment at (2 Fig. 16 to bring.
the eye piece into the same plane with that of the telescope B and with (for.
focussing) an independent adjustment at C³ for the part which holds the object
glass. The telescopes are both provided with cross hairs for correct observation.
The image of the object as viewed through the telescope B is inverted whilst.
the image as viewed through the telescope C is erected. The coincidence of the
images as seen through both telescopes is therefore very readily ascertained and
the distribution of light is more nearly equalized than would otherwise be the
case.
To give the distance with great exactitude and facility I provide two scales one
of which indicates say hundreds of yards and the other of which indicates say yards
in each of such hundreds although of course I do not limit myself to those precise
subdivisions.
For this purpose I secure to the base A (by clamping or otherwise) a bracket D
in which there is carried a double slide the first member E. of which can be moved
by a screw fin one direction by turning the head of the said screw the member E
being provided with a slider e moving in guides d of the bracket D (Figure 10).
The spring bears on and prevents back lash of the member E. The second
member F of the slide moves .vertically in guides e carried by the part E and is
borne upon by a spring es to prevent back lash and can be moved by a screw f³ in
a direction at right angles to the direction of movement of the first member E. The.
screw which gives movement to the first member is provided with a disc g having
a spiral groove on its face in which works a projection guided on any suitable
guide or bar such as that at 2 carried by the member D. A rod or girder i is
connected to the direct observation telescope C and this rod enters between
guides e carried by the member E and has a spring e3 bearing on a projection et
from the member E. The said rod or girder i has on it an adjustable projection
which is kept in contact with an adjustable inclined piece J carried by the second
member Fas hereinafter explained. When the screw which works the first member
is operated it carries with it the member which causes the arm connected to the
direct observation telescope C to be moved so that the angular position of the said
telescope is altered to a degree in accordance with the extent of movement of the
screw and so that when the two telescopes B and C are parallel the projection his
in the outermost convolution of the spiral groove in the disc g and when the direct
observation telescope is at.its greatest angular position relatively to the fixed
telescope B the said projection is in the innermost convolution of the said.spiral
groove. As in the former case the instrument is in the position of infinity and 'in the

page_text: +
later case the instrument is in position for observing objects at the shortest distance
for which the instrument is adapted it follows that I can mark a scale on the spiral of
the disc which scale will shew approximately (say in hundreds of yards) the distance
of the object observed when its images received by the two telescopes B and C
coincide.
The disc g may be provided with recesses into which the projection (which is then
formed as a spring plug) may enter to definitely fix the position of the said disc whilst
the finer measurements are being taken. In order to make a practically accurate
subdivision (into say yards) of these indications of hundreds of yards the adjustable
inclined piece J before named is used; which is carried by the piece j sliding in the
guides of the second member F so that the said inclined piece can. by means of the
screw be adjusted in a plane at right angles to the movement of the first member E.
This inclined piece on being traversed will cause the projection (from the rod i of
the moveable telescope C) to be moved and consequently the said telescope also to he
moved to an extent in accordance with the angle to which the said inclined piece J is
adjusted. As the extent of movement of the telescope for obtaining the exact
adjustment for coincidence of the images as seen by both eyes varies in an inverse
ratio to the distance of the object observed I alter the angle of the said inclined piece J
in accordance with the distance in say hundreds of yards to which the instrument is
adjusted by the aforesaid spiral groove in the disc g. This I effect by fixing the said
inclined piece J in a piece j centred by the pivots in a recess in the member F.
This piece is connected by spring stretchers or bars n to a plate p provided with a
boss and having a square hole fitted to slide on a stem p² carried by the projection p³
from a plate P centered at p to one of the guides e and to this plate P is secured a
cam piece so shaped as to alter the position of the inclined piece J to give the
increased movement necessary when the first member adjusted for the shorter
distances. This cam piece bears on a fixed part m secured to the bracket in which
the first member E moves so that it compels the hinged piece P (and consequently
through the plate p and stretcher n alɛo the inclined piece with its carrier j) to move
to the necessary extent to give the necessary inclination to the inclined piece J. pis
à spring which bears on a projection p from the piece P to press the cam l'into
contact with the fixed part m. The stretchers and the sliding of the plate p on the
stem p² permit the proper moving of the inclined piece J as its position is altered.
There is thus in taking an observation a first adjustment indicated by the spirally
grooved disc g and obtained by the movement of the first member tilting the moveable
telescope C and during this adjustment the cam and hinged piece m have caused an
angular movement of the inclined piece J to an extent corresponding to the distance
in hundreds of yards to which the instrument is adjusted. The head of the screw f³
may be marked with a scale to shew the finer adjustments of the member F. s being a
pointer for the said scale.
In Figures 11 and 12 I have shown a modification in which the second member F
is dispensed with the arm i being affixed to a piece q which is secured to the first
member E the said piece a consisting of two parts connected by a blade spring 9² to
prevent torsion of the rigid parts. In place of a disc g with spiral grooves a cylinder
or cone with a helically grooved periphery may be used.
Referring again to the Figures 9 and 10. After the first adjustment has been made
by moving the member E the screw ƒ of the second member F is operated and thereby
the carrier of the inclined pieco J is traversed and by reason of its angular surface
bearing on the projection from the telescope arm or girder that arm further tilts the
moveable telescope to an extent for each yard in accordance with the-hundreds of
yards to which the instrument has been set by the movement of the first member E.
The scales may be marked on any suitable part of the instrument other than those
shown.
1 prefer to obtain the divisions on the scales of the instrument by observation to
facilitate which I prefer to prepare a scale which has been divided with divisions
indicating the intersection of lines of sight from objects at varying distances whilst
the other line of sight is constant. This scale is set up at the proper distance from

page_text: the instrument and its divisions observed through the moveable telescope whilst the
instrument is firmly fixed and this will give the position for the markings of the
scale.
.
The instrument is capable of use in land or marine service. For example the
tubular metal masts of vessels may be used as a base provided that the telescopes are
in convenient position for the user and so reliable indications of range can be obtained
on shipboard.
Where there is a variable base, for instance where one line of sight is obtained
from the sea level I may make the length of the arm connecting the moveable
telescope with the measuring apparatus adjustable or the measuring apparatus
adjustable on the arm the proper adjustment to suit different levels of the sea being
indicated by a scale in connection with the adjustable parts.
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. In telemeters or range finders the combination with a base as described of two
telescopes arranged so that the two eyes of an observer can be applied thereto one
telescope receiving an image from one end of the base and the other telescope having
direct vision from the other end of the base one of the telescopes being adjustable and
provided with means for indicating its angular position substantially as herein before
described.
2. In telemeters or range finders the means for adjusting the telescope and for
measuring the angle of adjustment substantially as herein before described.
3. The device for adjusting and measuring the angle consisting of a disc cone or
cylinder for first adjusting and measuring approximately and an inclined plane for
making the second or finor adjustments and measurements the said inclined plane
being caused to have a greater or lesser inclination as the position of the first adjust-
ment is altered substantially as herein before described.
4. In telemeters or range finders the combination with a moveable telescope of a
lever arm or girder connected to or acted upon by an adjusting arrangement
substantially as hereinbefore described whether on the single adjustment plan of
Figures 11 and 12 or on the double adjustment plan of the other Figures of the
accompanying drawing.
5. The combination of the spirally grooved disc cone or cylinder and an inclined
plane for finer measurement the said inclined plane being automatically altered in
degree of incline substantially as and for the purpose herein before described.
6. The arrangement and combination of parts constituting the telemeter or range
finder substantially as herein before described and illustrated in the accompanying
drawings including the modifications herein before described and illustrated.
Dated this 5th day of July 1889
E. L. W. HASKETT-SMITH.