Improvements in Angle-measuring Instruments.
Year: 1894

page_text: Date of Application; 2nd Oct., 1894
Complete Specification Left, 1st Juy, 1895-Accepted, 2nd Oct., 1895
PROVISIONAL SPECIFICATION.
Improvements in Angle-measuring Instruments.
I, GEORG ADOLPH RUNG of St. Kongemgade 85, Copenhagen, in the Kingdom
of Denmark, Captain and Sub-director at the Meteorological Institute, Copenhagen
aforesaid, do hereby declare the nature of this invention to be as follows:-
This invention has reference to an instrument, which is intended, without the
reading off of any division of a circle by a nonius, vernier, or similar delicate
means for reading off, to determine accurately the angle between lines joining a
given point with two other points of which only one is visible from the said given
point, whilst from a point in the vicinity it is possible to see both the points.
An instrument according to this invention is shown in plan in Figure 1 of the
accompanying drawings and in vertical section in Figure 2, Figure 3 showing its
lower part, the arc. B, hereinafter mentioned, in plan.
The instrument consists of three principal parts: first, a sextant or other
suitable augle-measuring instrument based on double roffection (octant, semicircle,
pistor-circle or the like); secondly, a diopter or other apparatus for taking sights;
and, thirdly, a slide, capable of being moved along a divided circular arc.
The sextant or other angle-measuring instrument is as usual provided with two
mirrors, of which ones, is unsilvered on a part of its surface and is fixed in position
and so placed that it is possible through a sight hole H, or throngh a telescope, to
see directly one of the objects through the silvered part of the mirror, whilst it is
possible at the same time in the silvered part and by double reflection to see the
other object by suitably turning on its axis the other movable mirror S. The
latter mirror is by means of toothed wheels T and t or in any other suitable
manner so connected with an axle a that when the mirror S is turned, the angular
movements of the axle a will be exactly twice as large as those of the mirror S.
The diopter with its diametrically placed stands o and ol for taking sights, (or
any other sighting-apparatus that may be used) is in rigid connection with the
axle 0, and moves on a circular are which may be provided or not with graduations
the centre of which is at the axis of the axle a. The centre is, for practical
considerations, placed in the same vertical plane as the line between II and the
middle of the mirrors, but such an arrangement is not essential. The sighting-
apparatus may, as indicated in Figure 2, be constructed in such a manner, that
sighting can be effected either from o or from 01, i.e. in opposite directions.
The angle-measuring instrument and the sighting-apparatus are carried by a
slide L with which they may be jointed by means of a bolt b. This slide may, by
means of a pinion D, or in any other convenient way, be moved along the divided
arc B. The radius of this are may be made very long, so that a movement of
the slide from mark to mark along the arc B may cause a very slight angular
movement of the vertical sighting-plane of the diopter or other sighting apparatus
mployed.
Dated this 2nd day of October 1894.

page_text: R
COMPLETE. SPECIFICATION.
Improvements in Angle-measuring Instruments.
1, GEORG ADOLPH RUNG, of St. Kongemgade 85, Copenhagen, in the Kingdom
of Denmark, Captain and Sub-director at the Meteorological Institute, Copenhagen
aforesaid, 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 reference to an instrument, which is intended, without the
reading off of any division of a circle by a nonius;, vernier, or similar delicate
means for reading off, to determine or set off accurately the angle between lines
joining a given point with two other points of which only one is visible from the
enid, given point,, whilst from a point in the vicinity thereof it is possible to see
both the points..
: 1.
An instrument according to this invention is shown in the accompanying
drawings, Figure 1 being a plan, and Figure 2 a vertical section. Figure 3 shows
in plan, the lower part of the instrument, viz., an arc B hereinafter more particularly
described.
The instrument consists of three principal parts: first, a sextant, or other
suitable angle-measuring instrument based on double reflection (octant, semi-circle,
pistor-circle, or the like); secondly, a diopter or other apparatus for taking sights;
and, thirdly, a slide, capable of being, moved along a divided circular arc.
The sextant or other angle-measuring instrument is, as usual, provided with two
mirrors, of which one, s, is unsilvered on a part of its surface and is fixed in
position and so placed that it is possible through a sight-hole H, or through a
telescope, to see directly one of the objects through the unsilvered part of the
mirror, whilst it is possible at the same time in, the silvered part, and by double
reflection, to see the other object by suitably turning on its axis, the other or
movable mirror S. This latter mirror is, by means of toothed' wheels T and, t, or
in any other suitable manner,. connected with an axle a so that when the mirror S
is turned, the angular movement of the axle.a will be exactly twice as large as
that of the mirror S.
In consequence thereof a point outside the axle and in rigid conuection therewith,
will, at the moment when both objects are seen simultaneously, have moved through
an, angular distance from the initial position-that is the position. wherein the
directly seen object is visible and the mirrors sand S are parallel with each
other exactly equal to the visual angle between the objects.
The diopter with its diametrically placed stands o and o' for taking sights (or
any other sighting-apparatus that may be used), is in rigid connection with the
axle a, and moved on a circular are the centre of which is at the axis of the axle a,
and which may be provided or not with graduations. The centre a is, for practical
considerations, placed in the same vertical plane as the line between. H and the
middle of the mirrors, but such an arrangement is not essential. The sighting-
apparatus may, as indicated in Figure 2, be constructed in such a manner, that
sighting can be effected either from o, or from o, i.e. in opposite directions.
The angle-measuring instrument and the sighting-apparatus are carried by a
slide with which they may be jointed by means of a. bolt b. This slide may,, by
means of a piniou D, or in any other convenient way, be moved along the, divided
arc B. The radius of this are may be made very long, so that a movement of the
slide from mark to mark along the arc B, may canse a very slight angular
movement of the vertical sighting-plane of the diopter or other sighting-apparatus
employed.
1
In order that the mode of operating with the instrument may be clearly
understood I will now describe its use for pointing a cannon towards a mark that

page_text: cannot be seen from the cannon itself on account of some obstacle situate between
the cannon and the mark. Two cases may be considered :-
(1.) The mark can be seen by occupying a position-say, on the seat of the
carriage of the cannon-slightly higher than the cannon but in immediate
proximity thereto. The operator in this higher position directs his eye through
the holo H and the middle of the unsilvered part of the mirrors towards an
auxiliary point, which can be seen from the cannon also; and he then rotates the
mirror S from its initial position in which it is parallel with the mirror s, until the
mark to be aimed at is seen by double reflection in the silvered part of the mirror s
and in line with the said auxiliary point. If the diopter oo, and the angle-
measuring part of the instrument be kept in the relative positions they have now
assumed and the whole apparatus be rigidly attached to the cannon with the
vertical plane containing the line joining the hole H and the middle of the mirror s
coincident with, or parallel to, the axis of the cannon, the cannon can be directed
towards the mark by turning it until the auxiliary point aforesaid be sighted
through the diopter oo. Alterations in the lateral direction of the cannou can be
made by moving the instrument along the arc B and then turning the cannon until
the auxiliary point can be again seen through the diopter.
(2.) The mark can be seen from an auxiliary point which is a little on one side
of the cannon and from which the cannon also can be seen. The operator, placing
himself at the aforesaid auxiliary point, first directs his eye through the hole H
and the middle of the unsilvered part of the mirrors towards the part of the cannon
over which the axle a of the instrument will be subsequently situate; and he then
turns the mirror S until he sees, by double reflection and in the middle of the
silvered portion of the mirror s, the mark to be aimed at. The instrument is now
transferred to its proper place on the cannon, the diopter and the angle-measuring
portion being retained in the relative positions they have assumed, and the cannon
is turned until the diopter is directed towards the aforesaid auxiliary point.
To be perfectly accurate, parallax should be calculated and the correction made
therefor by moving the instrument along the arc B.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. An apparatus for measuring or setting off the angle between lines joining a
given point with two other points of which only one is visible from the said given
point whilst both are visible from another point in the vicinity thereof, comprising
a sextant, or other similar angle-measuring instrument based on double reflection
in combination with a sighting-apparatus (diopter, telescope, or the like), whose
vertical plane can be turned about an axis in such a manner that its angular
movement will be equal to the angle between the lines that is being measured by
the sextant, as set forth.
2. The combination of the apparatus specified in the preceding claim, or the
part constituting the sighting-apparatus thereof, with an arc of long radius, along
which the said apparatus, or part, can be moved by suitable means for the purpose
of measuring or setting off very small angular movements.
3. The improved angle measuring instrument constructed and operating
substantially as described and shown for the purpose specified.
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.