Year: 1887

page_text: Date of Application, 29th Mar., 1887
Complete Left, 15th Dec., 1887
Complete Accepted, 10th Feb., 1888
1, WILHELM THEODOR UNGE, of No. 7 Stureparken, Stockholm, Sweden, Staff
Captain, do hereby declare the nature of this invention to be as follows:-
This invention refers to an instrument for determining and measuring distances and
is particularly designed for military purposes.
The measurements are taken by observations made with the same instrument from
two stations situated comparatively close to each other.
The method of measurement is founded on the supposition that for an object at a
great distance, the distance sought can be considered equal to the length of the
hypothenuse, or else to the larger side of the right angled triangle which is supposed
to be constructed on the connecting line drawn between the points of observation as
a base, and with the opposite angle as large as the acute angle (a) which is formed
between lines drawn from the two stations to the mark or object.
This condition is assumed to be true provided the object does not lie far from a line
drawn from either of the points of observation at right angles to their connecting
line. The distance of a place or mark tbus situated is thus determined either to be
equal to the product of the length of the base and the inverted or reciprocal value of
the sine for the above mentioned acute angle (D = B
sin a
) or else the product
of the length of the base and the cotangent of the same angle (D= B. cotangent a).
The construction of the instrument is such that when measuring it is not necessary
to measure exactly or even know the absolute length of the distance between the
stations-the so called base-line-nor need this line be perpendicular to the imaginary
line joining the distant mark with either of the stations. The stations may, be chosen

page_text: at will, though they should be selected so that the so-called base-line is as nearly at
right angles to a line joining one of its ends with the distant object as the ground
allows of.
The measurement is taken by first placing the instrument on the one station and a
graduated tablet on the other station, and observing the distant object and the tablet.
The relative positions of the instrument and the tablet are then changed and again the
object and the tablet are observed. These observations give two numbers or factors by
direct readings, of which the one-the so called base-factor- is proportional to the
arbitrarily chosen distance between the stations and the other-the so called angle-
factor is proportional to the inverted value of the sine of the angle or if preferred to
the cotangent of the same angle between the imaginary lines drawn from the points
of observation to the mark, the product of these factors gives the distance sought.
In the event of the distance between two objects at a distance should be determined
the distance measurer or telemeter is provided with a complementary apparatus
consisting of two graduated arms movable round a common axis to be connected with
the telemeter in such a way that this axis coincides with the centre of the pivot round
which the frame of the telemeter revolves, and that the arms can be pointed at the two
distant objects respectively and left in those positions.
After having determined the distances to the two objects from the station and these
distances being measured out on the two arms respectively, the distance between the
two points thus marked out on the arms gives the distance sought.
The accompanying drawings show in fig. 1. the instrument in elevation partly in
section, fig. 2 the same in plan, the telescope however being turned to the side, and
fig. gives a front end view. Fig. 4 is a section of the telescope along the line 4-4
in fig. 1. Fig. 5 shows one side of the tablet; fig. 6 the same from the end. Fig. 7
shows a stand partly closed and fig. 8 the upper part of the stand seen from above,
(Figs. 5, 6, 7 and 8 being drawn on a reduced scale). Fig. 9 is a diagrammatic
representation of the manner in which the angle telescope is set up, and fig. 10
represents the visual field of the angle telescope when directed to a tablet. Figs. 11
and 12 show in side elevation and plan the contrivance to be fastened to the instrument
when it is necessary to ascertain the space between two points at a distance from the
places from whence the observations are taken.
The instrument consists of a telescope a and an angle-telescope b, which can be
turned round its longitudinal axis, the former capable of being displaced in relation to
the latter, and placed one above the other in a common frame, which can be turned
round a vertical support.
As a suitable support a conical pivot A is used adjustably fixed to a stand, on which
pivot the above mentioned tablet can also be set up.
The frame of the instrument consists of two end pieces c and d connected by a
tubular piece e.
The hinder endpiece d has a projecting part d', which is furnished with conical
holes, inside which there is a conical socket, round which it can be turned.
The socket is itself made to fit on to the stand-pivot A. or to some corresponding
support. An arm p is fixed to the socket / above the projecting part d' of the end-
piece d. This arm which passes through openings in the end pieces c and d carries
at its end a nut g for a screw which by a ball and socket joints is connected with
two pieces fixed on the foremost endpiece c. By turning this screw, the whole
frame can thus be made to revolve round the socket f.
The telescope a is supported by a plate i movable round a pivot k, fixed in the front
end piece c of the frame. At the other end of this plate there is a slot 1 in the form
of an are in which a screw m projects firmly fixed in the hinder endpiece d.
By means of the nut n of this screw, the plate i and at the same time, the telescope a
can be firmly fastened to the frame of the instrument in the desired position in relation
to the angle telescope.
The telescope is provided with an ordinary hair-cross. This hair-cross can be fixed
in the telescope, but in order to make the nice adjustment more easy, it is attached to
a frame which can be moved to either side by turning a screw (vide figure 4).

page_text: Inside the tubular part e is the angle-telescope 6 which consists of a common
telescope and a glass placed before the objective, or if preferred a prism.
This angle-telescope can be revolved round its longitudinal axis in conical holes
made in the endpieces c and d and is kept in its place by a spring y, which lies against
the hinder endpiece d, pressing the head of a stud h fastened to the telescope. The
tubular piece e has two diametrically placed openings e e¹ in front of the reflecting
surface of the angle-telescope.
The tablet (figs. 5 and 6) is also provided with a conical socket y, which fits the
stand pivot A, as also with a diopter y¹ y¹ so that the tablet may be placed at right
angles to the connecting line between the stations. On this tablet there is a point S
the so called directing point marked at a distance from the central line of the socket y,
as great as the distance between the central line of the socket f of the instrument and
the point of intersection T (vide figs. I and 9) between the reflecting surface and the
axis of revolution of the angle-telescope b. Right above this directing point S there
is a vertical line S₁ the so called line of angles and at the side of the directing point a
scale the so called basis-scale of which more will be said hereafter. The tablet is
made alike on both sides, so that it may be used at either station.
It is always
mounted in such a way that the directing point is at the same side of the central line
of the stand as the point T in the instrument at the other station.
In the focus of the angle-telescope there is a plate of glass (fig. 1) on which a
vertical line oo is drawn (figures 9 and 10) the so called zero-line. This line need
not intersect the axis of revolution of the angle-telescope; but one makes himself
independent of its position as also of the position of the axis of revolution of the angle-
telescope in relation to the optical axis, by adjusting the reflecting surface in such
a manner as the particular telescope taken and mounted in the frame renders
necessary.
The procedure is as follows:-
Three stands are set up Nos. 1, 2 and 3 in figure 9, with the pivots vertical and in
a straight line; the instrument is then placed on its middle stand (No. 2) in such a
manner that the axis of revolution of the angle-telescope is at right angles to the line
of the stands two tablets are then set up, turned in the same direction as the instrument
on the two other stands, care being taken that these are also at right angles to the line
of the stands.
By this arrangement the directing point S of the tablets and the point of inter-
section T between the axis of revolution of the angle-telescope and the reflecting
surface are thus on one and the same straight line which is rectangular to the axis of
revolution of the angle-telescope. This being completed the angle-telescope is rotated
on its longitudinal axis until the directing point of the one tablet for instance S in
No. 1 becomes visible in the telescope. Then the reflecting surface is turned so far
that the image of the point S falls on the zero-line o of the plate of glass in the focus
of the angle-telescope and when in this position the reflecting surface is fastened once
for all. From this adjustment it follows that if the angle-telescope b is turned 180
degrees round its axis of revolution the image of the second directing point S in No. 3
will also fall on the zero-line of the angle-telescope, which after being turned round
has a symmetrical position in relation to the axis of revolution (o' in fig. 9).
If the instrument is now moved, for instance to stand No. 1, the tablet of which
has been removed and the angle-telescope is revolved on its axis of revolution
180 degrees and directed so that the image of the directing point on the tablet of
No. 3 falls on the zero-line of the angle-telescope, it is a natural consequence that the
angle-telescope when in this position is parallel to its first position on stand No. 2
when directed thence to the directing point in No. 1 and that the point of reflection T
has taken the same place as the directing point in No. 1.
From what has just been mentioned it is plain that if now, when the instrument is
in this position, a tablet is set up on stand No. 2 at right angles to the line of the
stands, the image of its directing point must fall on the zero-line of the angle-
telescope.

page_text: From the fact just mentioned it is obvious that if but two stands are set up, and a
tablet is placed on the one, at right angles to the line of the stands, the instrument
being put on the other, and the angle-telescope of the instrument, is directed so that
the image of the directing point of the tablet falls on the zero-line of the angle-
telescope, afterwards changing the respective places of the instrument and the tablet,
directing the tablet rectangularly to the line of the stands, revolving the angle-
telescope 180 degrees and then the directing it so that the image of the directing point
falls on the zero-line, the result will be that the axis of revolution of the angle-
telescope now has a position which is parallel to the position it had on the former
stand.
If while the instrument is set up at the first station and while the directing point
of the tablet on the second station is covered by the zero-line in the angle-telescope (b)
the hair-cross of the telescope (a) is directed to a distant mark and the telescope a
fixed in this position to the common frame, and the whole instrument afterwards, the
angle-telescope being revolved 180 degrees round its longitudinal axis, moved to the
stand of the second station and a tablet placed on the stand at station No. 1, and then
the whole instrument is turned round on the pivot of the stand, until the image of the
directing point of the tablet at the first station falls on the zero-line of the angle-
telescope, then the position of the telescope a is parallel to the position which was held
by the telescope a when the instrument was at the first station. If from this position
the whole instrument is now turned on the pivot of the stand; until the image of the
park again falls on the hair-cross in the telescope a, this last revolution of the instru-
ment embraces as large an angle (a) as the angle between the lines of direction
from the two stations to the mark. The value of this angle can be obtained in
many ways.
In my instrument there is a scale, the so-called scale of angles on the glass plate a
in the focus of the angle-telescope the divisional lines of which are parallel to the
zero-line o of the angle-telescope, which also passes through the point of zero of the
scale.
During the last mentioned revolution of the instrument in order to direct the hair-
cross of the telescope to the object chosen for aim, the image of the directing point of
the tablet previously coinciding with the zero-line of the angle-telescope--moves,
together with the line of angles, from the zero-line along the scale, and stops at a
certain point where the image of the line of angles then intersects it. By reading the
point last mentioned (where the scale is intersected by the image of the line of angles)
a value is obtained from which a can, be calculated.
1
şin a
is
As however the distance is to be calculated from a formula in which
included, it is an advantage to use a scale which directly gives this value. This how-
ever cannot be done unless the unit of length of the scale is in a certain relation to
the focal distance of the angle-telescope. But as practical difficulties are met with in
obtaining an object-glass with accurately determined focal distance, an arbitrarily
chosen scale is used in this instrument, which thus gives K when K designates
a constant dependent of the focal distance of the angle-telescope and the unit of length
of the scale.
1
sin a
In order to obtain the necessary proportional value to the real length of the basis-
line, a line B-B. (vide fig. 10) parallel to the zero-line has been inscribed on the plate
of glass in the focal plane of the angle-telescope.
This line the so-called basis line has its place on the other side of the zero-line
comparatively to the scale of angles and at an arbitrary distance from the zero-line.
1 the zero-line of the angle-telescope is directed to the directing point of the tablet
on the other station, the basis-ne will fall somewhere on the scale - we have
before mentioned, as on the aforesaid tablet, and by dividing this scale experimentally
into equal parts, the real value of the distance between the stations can be read on the
scale. The length of the parts of this scale then depends on the arbitrarily chosen

page_text: K 1
sin a
This value
which is the reading of the basis-scale of the tablet aimed at, is called
K'
the "basis-factor" and the value
which is the reading of the scale of angle in
the angle-telescope is called the "angle-factor."
By multiplying these two factors the value sought D=
B
sun a
sin a
obtained.
Such a basis-scale as described is graduated in the following manner.
A mark is decided upon and a stand (No. 1) is placed at a certain known distance
from it, for instance 2100 metres, another stand (No. 2) being placed at an arbitrary
distance from the first but on a line formning a right angle to the direction from No. 1
to the mark.
Having placed the instrument on stand No. 1 and duly directed it to a tablet at
No. 2 and to the mark, and afterwards having removed it to No. 2 and then again
directed it to the mark, the point where the image of the line of angles of the tablet
moved to No. 1 intersects the scale of angles is noted.
Assuming that the scale now gives the so called angle-factor to be 70, the basis
factor for this position will be
2.100
70
=
30.
The instrument is now turned in the opposite direction so that the image of the
directing point falls on the zero-line of the angle-telescope, vide fig. 10, which shows
the visual field of the angle-telescope with the zero-line o-o, the basis-line B-B, the
scale of angles and also the image of a tablet.
That point of the future scale on the tablet where the basis-line of the angle-
telescope now intersects the line is marked out and denoted by 30. By afterwards
dividing the distance between the directing point and the last mentioned point on the
tablet into 30 parts and marking out parts just as large in the opposite direction the
basis-scale which corresponds to the instrument is obtained. For such distances
between the points of observation, when it is necessary to move the object glass so as
to see clearly, a correction is made of the length of the corresponding scale-parts of
the basis-scale.
From what has just been said, it is apparent that the constant K, which is contained
both in the basis-factor and in the angle-factor K- is dependant on the arbi-
B
K
sin a
trarily chosen size of the scale of angle and the arbitrarily chosen focal distance of the
object glass in the angle-telescope, but by the manner in which the basis-scale has
been graduated, as we have seen, the value of this constant need not be known for
taking measurements.
As the basis-scale gives a value, which is proportional to the distance between the
points of observation, the basis-factor, and with it the distance sought, will be too
large if the basis-line be not at right angles to the direction from either of the points
of observation to the object.

page_text: In order to correct the fault which thus arises by the so called oblique position of
the stands, a graduated scale, found experimentally, is placed at the edge of the curved
slot in the plate i (vide fig. 2) by which the distance found must be diminished. The
middle of the nut n shows that number which is to be used in every particular case.
Such a correction, however need not be effected for military purposes until the angle
between the telescope and angle-telescope is more than 4 to 5º.
The supports for the fixture of the instrument can at option consist of a couple of
carriages, trees, etc. to which suitable fixtures have been fastened either beforehand
or for the occasion.
To make the telemeter or Distance-measurer more suitable for military purposes
two portable supports or stands, exactly like each other are specially constructed.
A (figures 7 and 8) is an upright adjustable pivot connected by a ball, which by
friction is kept in the position desired for the pivot to the head of the stand H which
is supported by three legs breast high fixed to the head by hinges. Each leg has a
joint L about half way up.
The upper part of the legs is double so that the lower part can be let down into the
upper when it is turned round the pivot of the joint. By the stoppers R or other
similar arrangement, the legs are kept straight when resting on the ground.
The head of the stand is so constructed that after being doubled up, the legs. can be
turned upwards as seen in fig. 7, and thus form a protection surrounding the pivot
and its fastenings like a case.
The Distance Measurer or Telemeter is used in the following manner.
The instrument for observation is set upon a stand at station No. 1 and the tablet
on another stand at station No. 2. The upper edge of the tablet, as also the instru-
ment, receives according to eye-measure a horizontal position by the movability of the
pivot. The place of the stand No. 2 ought to be chosen in such a manner that the
connecting line between No. 1 and No. 2 is as nearly at right angles to the line of
direction from No. 1. to the distant object as the ground allows of, so that no correction
for "oblique position" need be made after measurement.
For this purpose the stand No. 2 is placed on that line which the diopter-plane d" "1
of the instrument (figs. 1-2) points out after the telescope of the instrument from
No. 1. has been directed to the distant object. The diopter of the basis-scale or of the
tablet is directed to stand No. 1 and the angle-telescope with the aid of the diopter
plane d¹¹ to stand No. 2, when the basis-scale will be visible in the angle-telescope.
With the assistance of the adjusting screw the whole instrument is so directed that
the zero-line o-o of the scale of angle.intersects the directing point S (fig. 10).
The point of intersection of the basis-line B-B with the basis-scale denotes the
basis-factor of which a note is made.
The nut n is now loosened and the telescope a turned so that the distant object or
mark becomes visible in the telescope. The nut n is then screwed home and by means
of the screw the vertical line of the hair-cross of the telescope is now directed to
cover the mark.
The image of the directing point being thus covered by the zero-line of the angle-
telescope as also that of the mark by the hair-cross of the telescope
The instrument is now moved to stand No. 2 and the tablet to No. 1 where the
tablet by means of its diopter is directed to stand No. 2. The angle-telescope is turned
round its longitudinal axis about 180° so that the tablet on stand No. 1 becomes
visible, after which the whole instrument is revolved round the stand-pivot so that the
mark is seen in the telescope a. By the aid of the adjusting-screw of the instrument
the telescope is afterwards carefully directed so that the vertical line of the hair-cross
falls on the mark in the same manner as when directed from stand No. 1. This being
done, observations are made by the angle-telescope, as to where the image of the line
of angle intersects the scale of angle; the division of the scale read then forms the
angle-factor.
The basis- and angle-factors are then multiplied when the product gives the

page_text: This multiplication is best done by the help of a so called sliding or calculating rule
graduated according to the logarithuns of the factors.
Should it be considered necessary to take any notion of the fault that arises from
oblique position the per cent. number at the slot 1, fig. 2, must be observed, and the
distance calculated be lessened by the given per cent number.
To ascertain the distance between two distant points, visible from the place of
observation, that apparatus is used which is shown in figs. 11 and 12. It consists of
two arms, each separately movable round a common axis, and can be applied to the
instrument in such a manner that the axis of rotation of the arms coincides with the
axis of revolution of the frame of the instrument.
For this purpose the one arm C is fixed to a cylindrical socket D, which by friction
can be pushed down into a hole A', bored in the middle of the stand-pivot A. The
second arm C is provided with a pivot E. stuck into the socket D and loosely fastened
to it by the nut T so that it can easily be turned in the socket. The inner sides of the
arms are bounded by straight lines, which when drawn out intersect the common axis.
In the projecting part d' of the frame of the instrument a pin is fixed, and the
arms CC have each a part G G¹ going downwards and so situated that when the arms
are laid together so that the parts G G are on each side of the pivot and touch it,
the inner sides of the arms are on the same vertical plane above and close to each
other. The inner edges of the arms are divided into equal parts from their axis of
motion, each answering, for instance to 100 metres.
When the distance between two objects or marks that are visible but at a distance from
the station of observation, is to be measured, the distance from the station to the two
marks must first be ascertained, for instance with the Telemeter or Distance Measurer
as before described.
Afterwards the socket D of the arms is placed in the pivot hole A¹ so that the
parts G G are on each side of the pin d, the whole frame of the instrument is then
revolved, so that the hair-cross of the telescope a falls on the mark to the right, or on
that one of the marks, which is so situated that the pin d moves with it the arm C
fixed to the socket D when the arm C also turns. After taking the arm it must be
ascertained that the part G lies against the pin d. The whole frame of the instru-
ment is then revolved in the other direction until the hair-cross of the telescope a
is on the second mark, without however, using the micrometer screw w. In consequence
of the friction of the socket D in the hole A, the arm C is retained and the arm C is
moved by the pin d.
After having aimed at the second mark it is necessary to ascertain whether the
part G of the arm Clics close against the pin d. By taking these directions the
inner sides of the arms form an angle to each other which is as large as the angle
between the directions from the station of observation to the distant marks. If the
known distances to the marks are now marked on the respective arms counting from
the point of revolution and these points of the arms are connected, a triangle is
obtained having angles equal to that which is formed by the point of observation and
the two distant marks, and it is only necessary to measure this connecting line with
the same measure as that with which the arms are divided to know the distance sought
between the two distant marks in as nice a manner as is necessary for military purposes.
The measurement of the distance between the points of the arms can be taken in
many ways for instance with a compass which can afterwards be placed on the scale of
either of the arms where the readings are taken.
The distance can also be read direct by a loose scale, divided in the same manner,
which is placed between the points mentioned.
For instance if the distance to the one distant object be 3650 metres and to the
other 2075 metres, the corresponding points of the graduated arms are connected as
shown in fig. 12, and the length of this line of connection, in the scale used, gives the
distance sought between the distant objects or marks.
This way of bringing about the parallel placing of an instrument which has been
described, after moving it from one place of observation to another, can of course be
used for other surveying instruments than the Distance-Measurer.

page_text: The telescope a can also be replaced by a diopter or other such instrument of
observation.
Instead of using what has in the preceding description been called the basis-scale,
and an angle-telescope with a basis-line, if preferred the distance between the stations
of observation can be measured in any other way in the scale necessary for the
instrument.
W. LLOYD WISE,
Per C. E. Brougham,
46, Lincoln's Inn Fields, London, W.C
Agent for the Applicant.

page_text: I, WILHELM THEODOR UNGE, of No. 7 Stureparken, Stockholni, Sweden, Staff
Captain, 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 refers to an instrument for determining and measuring distances
and is particularly designed for military purposes.
The measurements are taken by observations, made with the same instrument from
two stations situated comparatively close to cach other.
The method of measurement is. founded on the supposition that for an object at a
great distance, the distance sought can be considered equal to the length of the
hypothenuse, or else to the larger side of the right angled triangle which is supposed
to be constructed on the connecting line drawn between the points of observation as
a base, and with the opposite angle as large as the acute angle (a) which is formed
between lines drawn from the two stations to the mark or object.
This condition is assumed to be true provided the object does not lie far from a line
drawn from either of the points of observation at right angles to their connecting
line. The distance of a place or mark thus situated is thus determined either to be
equal to the product of the length of the base and the inverted or reciprocal value of
D-B-
the sine for the above mentioned acute angle (D
sin
or
or else the product of the
length of the base and the cotangent of the same angle (D B cotangent a).
The construction of the instrument is however such that when measuring it is not
necessary to measure exactly or even know the absolute length of the distance between
the stations-the so called basis-line-nor need this line be perpendicular to the
imaginary line joining the distant mark with either of the stations. The stations may be
chosen at will, though they should be selected so that the so called basis-line is
as nearly at right angles to a line joining one of its ends with the distant object as
the ground allows of.
The measurement is taken by first placing the instrument on the one station and
a graduated tablet on the other station, and observing the distant object and the tablet.
The relative positions of the instrument and the tablet are then changed and again
the object and the tablet are observed. These observations give two numbers or
factors by direct readings, of which the one the so called basis-factor-is proportional
to the arbitrarily chosen distance between the stations, and the other-the so called
angle factor-is proportional to the inverted value of the sine of the angle or if
preferred to the cotangent of the same angle between the imaginary lines drawn from
the points of observation to the mark, the product of these factors gives the distance
sought.
In the event of the space separating two objects at a distance being required to be

page_text: dertermined the distance measurer or telemeter is provided with a complementary
apparatus consisting of two graduated arms movable round a common axis to be
connected with the telemeter in such a way that this axis coincides with the centre of
the pivot round which the frame of the telemeter revolves, and that the arms can be
pointed at the two distant objects respectively and left in those positions. After
having determined the distances to the two objects from the station and these distances
being measured out on the two arms respectively, the distance between the two points
thus marked out on the arms gives the distance sought.
Referring to the drawings filed with my Provisional Specification Fig. 1 shews the
instrument in elevation partly in section, fig. 2 the same in plan, the telescope however
being turned to the side, and fig. 3 gives a front end view. Fig. 4 is a section of the
telescope along the line 4-4 in fig. 1. Fig. 5 shows one side of the tablet ; fig. 6
the same from the end. Fig. 7 shows a stand partly closed and fig. 8 the upper part
of the stand seen from above, (Figs. 5, 6, 7 and 8 being drawn on a reduced scale).
Fig. 9 is a diagrammatic representation of the manner in which, the angle telescope
is set up, and fig. 10 represents the visual field of the angle telescope when directed
to a tablet. Figs. 11 and 12 show in side elevation and plan the contrivance to be
fastened to the instrument when it is necessary to ascertain the space between two
points at a distance from the places from whence the observations are taken.
The instrument consists of a telescope a and an angle-telescope b, which can be
turned round its longitudinal axis the former capable of being displaced in relation
to the latter, and placed one above the other in a common frame, which can be turned
round a vertical support. As a suitable support a conical pivot A is used adjustably
fixed to a stand, on which pivot the above mentioned tablet can also be set up.
The frame of the instrument consists of two end pieces c and d, connected by a
tubular piece e.
The hinder end piece d has a projecting part d', which is furnished
with conical holes, inside which there is a conical socket f, round which it can be
turned. The socket is itself made to fit on to the stand-pivot A, or to some
corresponding support. An arm p is fixed to the socket fabove the projecting part d'
of the end piece d. This arm p which passes through openings in the end pieces c
and d carries at its end a nut q for a screw r which by a ball and socket joint s is
connected with two pieces t¹ fixed on the foremost end piece c. By turning this
screw r, the whole frame can thus be made to revolve round the socket f.
The telescope a is supported by a plate i movable round a pivot k, fixed in the front
end piece c of the frame. At the other end of this plate i there is a slot in the form
of an arc in which a screw m projects firmly fixed in the hinder end piece d. By
means of the nut n of this screw, the plate i and at the same time, the telescope a can
be firmly fastened to the frame of the instrument in the desired position in relation to
the angle telescope. The telescope is provided with an ordinary hair-cross. This
hair-cross can be fixed in the telescope, but in order to make the nice adjustment
more easy, it is attached to a frame which can be moved to either side by turning a
screw (vide figure 4).
Inside the tubular part is the angle telescope 6 which consists of a common
telescope and a glass placed before the objective, or if preferred a prism. This
angle-telescope can be revolved round its longitudinal axis in conical holes made in
the end-pieces c and d and is kept in its place by a spring y, which lies against the
hinder end-piece d, pressing the head of a stud fastened to the telescope. The
tubular piece e has two diametrically placed openings e¹ e¹ in front of the reflecting
surface of the angle-telescope.
The tablet (figs. 5 and 6) is also provided with a conical socket y, which fits the
stand pivot A, as also with a diopter y¹ y¹ so that the tablet may be placed at right
angles to the connecting line between the stations. On this tablet there is a point S
the so called directing point marked at a distance from the central line of the socket y,
as great as the distance between the central line of the socket f of the instrument and
the point of intersection T (vide figs. 1 and 9) between the reflecting surface and the
axis of revolution of the angle-telescope b. Right above this directing point S.there
is a vertical line S¹ the so called line of angles and at the side of the directing point

page_text: a scale the so called basis-scale of which more will be said hereafter. The tablet
is made alike on both sides, so that it may be used at either station. It is always
mounted in such a way that the directing point is at the same side of the central line
of the stand as the point T in the instrument at the other station.
In the focus of the angle-telescope there is a plate of glass (fig. 1) on which a
vertical line o-o is drawn (figures 9 and 10) the so called zero-line. This line need
not intersect the axis of revolution of the angle-telescope; but one makes himself
independent of its position as also of the position of the axis of revolution of the
angle-telescope in relation to the optical axis, by adjusting the reflecting surface in
such a manner as the particular telescope taken & mounted in the frame renders
necessary. The procedure is as follows:-Three stands are set up Nos. 1, 2 and 3
in figure 9, with the pivots vertical and in a straight line; the instrument is then
placed on the middle stand (No. 2) in such a manner that the axis of revolution of
the angle-telescope is at right angles to the line of the stands; two tablets are then
set up, turned in the same direction as the instrument on the two other stands, care
being taken that these are also at right angles to the line of the stands. By this
arrangement the directing points S of the tablets and the point of intersection T
between the axis of revolution of the angle-telescope and the reflecting surface are
thus on one and the same straight line which is rectangular to the axis of revolution
of the angle-telescope. This being completed the angle-telescope is rotated on its
longitudinal axis until the directing point of the one tablet, for instance S in No. 1,
becomes visible in the telescope. Then the reflecting surface is turned so far that
the image of the point S¹ falls on the zero-line o of the plate of glass in the focus of
the angle-telescope and when in this position the reflecting surface is fastened once
for all. From this adjustment it follows that if the angle-telescope 6 is turned
180 degrees round its axis of revolution the image of the second directing point S
in No. 3 will also fall on the zero-line of the angle-telescope, which after being turned
round has a symmetrical position in relation to the axis of revolution (o' in fig 9).
If the instrument is now moved, for instance to stand No. 1, the tablet of which has
been removed and the angle telescope is revolved on its axis of revolution 180 degrees
and directed so that the image of the directing point on the tablet of No. 3 falls on
the zero-line of the angle-telescopo, it is a natural consequence that the angle-
telescope when in this position is parallel to its first position on stand No. 2 when
directed thence to the directing point in No. 1 and that the point of reflection T has
taken the same place as the directing point in No. 1.
From what has just been mentioned it is plain that if now, when the instrument is
in this position, a tablet is set up on stand No. 2, at right angles to the line of the
stands, the image of its directing point must fall on the zero-line of the angle-
telescope.
From the fact just mentioned it is obvious that if but two stands are set up, and a
tablet is- placed on the one, at right angles to the line of the stands, the instrument
being put on the other, and the angle-telescope of the instrument is directed so that
the image of the directing point of the tablet falls on the zero-line of the angle-
telescope, afterwards changing the respective places of the instrument and the tablet,
directing the tablet rectangularly to the line of the stands, revolving the angle-
telescope 180 degrees and then directing it so that the image of the directing point
falls on the zero-line, the result will be that the axis of revolution of the angle-
telescope now has a position which is parallel to the position it had on the former
stand:
If while the instrument is set up at the first station and while the directing point of
the tablet on the second station is covered by the zero-line in the angle-telescope (b)
the hair-cross of the telescope (a) is directed to a distant mark and the telescope a
fixed in this position to the common frame, and the whole instrument afterwards, the
angle-telescope being revolved 180 degrees round its longitudinal axis, moved to the
stand of the second station and a tablet placed on the stand at station No. 1, and then
the whole instrument is turned round on the pivot of the stand, until the image of
the directing point of the tablet at the first station falls on the zero-line of the angle-

page_text: telescope, then the position of the telescope a is parallel to the position which was
held by the telescope a when the instrument was at the first station. If from this
position the whole instrument is now turned on the pivot of the stand, until the
image of the mark again falls on the hair-cross in the telescope a, this last revolution
of the instrument embraces as large an angle (a) as the angle between the lines of
direction from the two stations to the mark. The value of this angle can be obtained
in many ways.
In my instrument there is a scale, the so called scale of angles on
the glass plate in the focus of the angle telescope the divisional lines of which are
parallel to the zero-line o of the angle-telescope which also passes through the point of
zero of the scale.
During the last mentioned revolution of the instrument in order to direct the hair-
cross of the telescope to the object chosen for aim, the image of the directing point
of the tablet previously coinciding with the zero-line of the angle-telescope-moves,
together with the line of angles, from the zero-line along the scale, and stops at a
certain point where the image of the line of angles then intersects it. By reading
the point last mentioned (where the scale is intersected by the image of the line of
angles) a value is obtained from which a can be calculated."
As however the distance is to be calculated from a formula in which
1
sin a
15
included, it is an advantage to use a scale which directly gives this value. This
however can not be done unless the unit of length of the scale is in a certain relation
to the focal distance of the angle telescope. But as practical difficulties are met with
in obtaining an object-glass with accurately determined focal distance, an arbitrarily
chosen scale is used in this instrument, which thus gives K when K designates
a constant dependent of the focal distance of the angle-telescope and the unit of
length of the scale.
1
sin a
In order to obtain the necessary proportional value to the real length of the basis-
line, a line B-B (vide fig. 10) parallel to the zero-line has been inscribed on the
plate of glass in the focal plane of the angle-telescope.
This line the so-called basis-line has its place on the other side of the zero line
comparatively to the scale of angles and at an arbitrary distance from the zero-line.
If the zero-line of the angle-telescope is directed to the directing point of the tablet
on the other station, the basis-line will fall somewhere on the scale - we have
before mentioned, as on the aforesaid tablet, and by dividing this scale experimentally
into equal parts, the real value of the distance between the stations can be read on
the scale. The length of the parts of this scale then depends on the arbitrarily chosen
distance between the zero-line and the basis-line on the plate of glass in the angle-
telescope and on the focal distance of the angle-telescope.
As, however, the so called scale of angle does not give the real value of
but
sin a'
this value multiplied by a constant, which depends on the construction of the angle-
telescope it is an advantage if the basis-scale does not give the real distance between
the stations viz. B in the formula D= B but such a value as multiplied by the
1
sin a'
value of K. observed at the time gives the value sought of the distance to the
sin a
remote object or aim, thus-
B
K'
B
K
This value which is the reading of the basis-scale of the tablet aimed at, is called
the "basis-factor" and the value K
1
Sin a
which is the reading of the scale of angle in
the angle-telescope is called the "angle-factor." By multiplying these two factors the
1
B
K
sin a
value sought D=K
B1
is obtained.
sin a

page_text: Such a basis-scale as described is graduated in the following manner.
A mark is decided upon and a stand (No. 1) is placed at a certain known distance
from it, for instance 2100 meters, another stand (No. 2) being placed at an arbitrary
distance from the first but on a line forming a right angle to the direction from No. 1
to the mark.
Having placed the instrument on stand No. 1 and duly directed it to a tablet at
No. 2 and to the mark, and afterwards having removed it to No. 2 and then again
directed it to the mark, the point where the image of the line of angles of the tablet
moved to No. 1 intersects the scale of angles is noted. Assuming that the scale now
gives the so called angle-factor to be 70, the basis-factor for this position will
2100
be = 30. The instrument is now turned in the opposite direction so that the
70
image of the directing point falls on the zero-line of the anglo-telescope, vide fig. 10,
which shows the visual field of the angle-telescope with the zero-line o-o, the basis-
line B-B, the scale of angles and also the image of a tablet.
=
That point of the future scale on the tablet where the basis-line of the angle-
telescope now intersects the line - is marked out and denoted by 30. By afterwards
dividing the distance between the directing point and the last mentioned point on the
tablet into 30 parts and marking out parts just as large in the opposite direction the
basis-scale which corresponds to the instrument is obtained. For such distances
between the points of observation, when it is necessary to move the object glass so as
to see clearly, a correction is made of the length of the corresponding scale-parts of
the basis-scale.
B
K
From what has just been said it is apparent that the constant K, which is contained
both in the basis-factor and in the angle-factor K is dependant on the
sin a
arbitrarily chosen size of the scale of angle and the arbitrarily chosen focal distance
of the object glass in the angle-telescope, but by the manner in which the basis-scale
has been graduated, as we have seen, the value of this constant need not be known
for taking measurements.
As the basis-scale gives a value, which is proportional to the distance between the
points of observation, the basis-factor, and with it the distance sought, will be too
large if the basis-line be not at right angles to the direction from either of the points
of observation to the object. In order to correct the fault which thus arises by the
so-called oblique position of the stands, a graduated scale, found experimentally, is
placed at the edge of the curved slot in the plate i (vide fig. 2) by which the distance
found must be diminished. The middle of the nut n shows that number which is to
be used in every particular case. Such a correction however need not be effected for
military purposes until the angle between the telescope and angle-telescope is more
than 4 to 5º.
The supports for the fixture of the instrument and tablet can at option consist of a
couple of carriages, trees, etc. to which suitable fixtures have been fastened either
before-hand or for the occasion. To make the Telemeter or Distance-Measurer more
suitable for military purposes two portable supports or stands, exactly like each other
are specially constructed.
A (figures 7 and 8) is an upright adjustable pivot connected by a ball and socket
joint, which by friction is kept in the position desired for the pivot, to the head of the
stand H which is supported by three legs breast high fixed to the head by hinges.
Each leg has a joint L about half way up.
The upper part of the legs is double so that the lower part can be let down into the
upper when it is turned round the pivot of the joint. By the stoppers R or other
similar arrangement, the legs are kept straight when resting on the ground.
The head of the stand is so constructed that after being doubled up, the legs can be
turned upwards as seen in fig. 7, and thus form a protection surrounding the pivot and
its fastenings like a case.
The Distance-Measurer or Telemeter is used in the following manner.
The instrument for observation is set up on a stand at station No. 1 and the tablet

page_text: on another stand at station No. 2. The upper edge of the tablet, as also the instru-
ment, receives according to eye-measure a horizontal position by the movability of the
pivot. The place of the stand No. 2 ought to be chosen in such a manner that the
connecting line between No. 1 and No. 2 is as nearly at right angles to the line of
direction from No. 1 to the distant object as the ground allows of, so that no correction
for "oblique position" need be made after measurement.
For this purpose the stand No. 2 is placed on that line which the diopter-plane d" d
of the instrument (figs. 1-2) points out after the telescope of the instrument from
No. 1 has been directed to the distant object.
The diopter of the basis-scale or of the tablet is directed to stand No. 1 and the
angle-telescope with the aid of the diopter plane ¹¹d to stand No. 2, when the basis-
scale will be visible in the angle-telescope. With the assistance of the adjusting
screw the whole instrument is so directed that the zero-line oo of the scale of angle
intersects the directing point S (fig. 10).
The point of intersection of the basis-line B-B with the basis-scale denotes the
basis-factor of which a note is made.
The nut n is now loosened and the telescope a turned so that the distant object or
mark becomes visible in the telescope.
The nut n is then screwed home and by means of the screw u the vertical line of
the air-cross of the telescope is now directed to cover the mark.
The image of the directing point being thus covered by the zero-line of the angle-
telescope as also that of the mark by the hair-cross of the telescope.
The instrument is now moved to stand No. and the tablet to No. 1 where the
tablet by means of its diopter is directed to stand No. 2. The angle-telescope is
turned round its longitudinal axis about 180° so that the tablet on stand No. 1
becomes visible, after which the whole instrument is revolved round the stand-pivot
so that the mark is seen in the telescope a.
By the aid of the adjusting-screw r of the instrument the telescope is afterwards
carefully directed so that the vertical line of the air-cross falls on the mark in the
same manner as when directed from stand No. 1.
This being done, observations are made by the angle-telescope, as to where the
image of the line of angle intersects the scale of angle; the division of the scale read
then forms the angle factor.
The basis- and angle-factors are then multiplied when the product gives the
distance.
This multiplication is best done by the help of a so called sliding or calculating
rule graduated according to the logarithms of the factors.
Should it be considered necessary to take any notice of the fault that arises from
oblique position the per cent. number at the slot l, in front of the middle of the nut n
fig. 2, must be observed, and the distance calculated be lessened by the given per cent.
number.
To ascertain the distance between two distant points, visible from the place of
observation, that apparatus is used which is shewn in figs. 11 and 12. It consists of
two arms, each separately moveable round a common axis, and can be applied to the
instrument in such a manner that the axis of rotation of the arms coincides with the
axis of revolution of the frame of the instrument. For this purpose the one arm C is
fixed to a cylindrical socket D, which by friction can be pushed down into a hole A,
bored in the middle of the stand-pivot A. The second arm C₁ is provided with a
pivot E. stuck into the socket D and loosely fastened to it by the nut F so that it can
easily be turned in the socket. The inner sides of the arms are bounded by straight
lines, which when drawn out intersect the common axis. In the projecting part d of
the frame of the instrument a pin is fixed, and the arms CC have each a
part G. G¹ going downwards and so situated that when the arms are laid together so
that the parts G G are on each side of the pivot d¹ and touch it, the inner sides of
the arms are on the same vertical plane above and close to each other. The inner
edges of the arms are divided into equal parts from their axis of motion, each answering,
for instance to 100 metres.

page_text: When the distance between two objects or marks that are visible but at a distance
from the station of observation, is to be measured, the distance from the station to the
two marks must first be ascertained, for instance with the Telemeter or Distance
Measurer as before described and afterwards the socket D of the arms is placed in the
pivot hole A so that the parts G G' are on each side of the pin d, the whole frame
of the instrument is then revolved; so that the hair-cross of the telescope a falls on the
mark to the right, or on that one of the marks, which is so situated that the pin d
moves with it the arm C fixed to the socket D. when the arm C¹ also turns.
taking the arm it must be ascertained that the part G lies against the pin d. The
whole frame of the instrument is then revolved in the other direction until the hair
cross of the telescope a is on the second mark, without, however, using the micrometer
screw u.
In consequence of the friction of the socket D in the hole A', the arm b is
retained and the arm C is moved by the pin 111.
After
After having aimed at the second mark it is necessary to ascertain whether the
part Gof the arm C³ lies close against the pin d. By taking these directions the
inner sides of the arms form an angle to each other which is as large as the angle
between the directions from the station of observation to the distant marks. If the
known distances to the marks are now marked on the respective arms counting from
the point of revolution and these points of the arms are connected a triangle is
obtained having angles equal to that which is formed by the point of observation and
the two distant marks, and it is only necessary to measure this connecting line with the
same measure as that with which the arms are divided to know the distance sought
between the two distant marks in as nice a manner as is necessary for military
purposes. The measurement of the distance between the points of the arms can be
taken in many ways for instance with a compass which can afterwards be placed on
the scale of either of the arins, where the readings are taken. The distance can also
be read direct by a loose scale divided in the same manner, which is placed between
the points mentioned. For instance if the distance to the one distant object be
3650 metres and to the other 2075 metres, the corresponding points of the graduated
arms are connected as shown in fig. 12, and the length of this line of connection,
in the scale used, gives the distance sought between the distant objects or
marks.
This way of bringing about the parallel placing of an instrument which has been
described, after moving it from one place of observation to another, can of course be
used for other surveying instruments than the Distance-Measurer. The telescope a can
also be replaced by a diopter or other such instrument of observation.
Instead of using what has in the preceding description been called the basis-scale,
and an angle-telescope with a basis-line, if preferred the distance between the stations
of observation can be measured in any other way in the scale necessary for the
instrument.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. The combination with the telescope of a surveying instrument, of a horizontal
telescope capable of being revolved on its longitudinal axis, and provided with a
reflecting surface, and a zero line, substantially as described and for the purpose
specified.
2. The use in combination with a surveying instrument fitted with a longitudinal
telescope provided with a reflecting surface and capable of being revolved, as referred
to in the previous claim, of a tablet or other object mounted on a support, similar
to the support of the surveying instrument, and carrying a mark, or marks, to serve as
the point of observation for the revolving telescope substantially as described and for
the purposes specified.
3. In combination with the telescope of a surveying instrument and a horizontal
telescope provided with a reflecting surface and capable of being revolved on its
longitudinal axis, a scale in the focal plane of the latter telescope, the said scale being

page_text: divided according to increasing angles or according to some function of such angles,
the use of the said scale being to determine the angle between the lines joining two
stations of observation to a distant object or mark substantially as described and in the
manner specified.
4. The hereinbefore described method or process of measuring distances by the use
of two combined telescopes, of which one is provided with a reflecting surface, a zero
line, a basis line and a scale of angles as described and is capable of being revolved on.
its longitudinal axis, and a tablet with a directing point, a line of angles and a basis
scale the distance being found by multiplying the reading of the basis scale by the
reading of the scale of angles.
5. A surveying instrument, constructed arranged and operating substantially as
described with reference to Figs. 1 to 6 of the drawings.
6. An angle measuring instrument consisting of two straight edges hinged
together on a suitable support and adaptable to the frame or stand of the instrument
mentioned in claim 5 as described and illustrated in figs. 11 and 12 of the drawings
substantially for the purpose set forth.
7. In combination with a surveying instrument of the kind referred to in claim 1
a tripod stand constructed substantially as described with reference to Figs. 7 and 8
of the drawings.
Dated this 15th day of December 1887.
WILHELM THEODOR UNGE.