An Improved Instrument for Measuring Angles, suitable for Judging Distances and other purposes.
Year: 1890

page_text: Date of Application, 20th Nov., 1890
Complete Specification Left, 19th Aug.. 1891-Accepted, 7th Nov., 1891
PROVISIONAL SPECIFICATION.
An Improved Instrument for Measuring Angles, suitable for Judging
Distances and other purposes.
I, JAMES PALMER CAMPBELL of Wyndham Street, in the City of Auckland,
in the Colony of New Zealand, Barrister, now residing at Wood's Hotel, Furnivals
Jun, London, (a communication to me from abroad by Thomas William Mayson of
Ponsonby in the City of Auckland, New Zealand, Draughtsman,) do hereby
declare the nature of this invention to be as follows:-
This invention relates to a convenient form of micrometer for measuring small
angles. In the focus of the eye piece of a telescope there is a fixed and also a
moving cross wire. The moving cross wire is connected to a lever pivotted to the
telescope, so that, as the lever is turned about its pivot the distance between the
two cross wires is varied. There is a slide upon the telescope which when moved
along it varies the inclination of the lever to it and thus alters the distance between
the two cross wires. The lever is graduated and the slide acts as an index. If
the graduations are suitably adjusted the angle may be read off without calculation,
or the distance of any object of known height may be read in yards &c. the object
being apparently inclosed by the two wires.
For use at sea the instrument (being provided with a level parallel to the line of
sight) is raised or lowered by means of an adjusting screw until the fi.:ed wire is
on a line with the water level of the object vessel or fort then the slide is moved
until the level is seen by the aid of a reflector to be level the distance of the object
being then indicated on the lever or beam.
Further by the addition of a level the clevation as well as the distance of an
object of known height may be read thus saving much time in surveying.
The instrument can also be adapted for the sighting of guns. In this case there
are two moving wires the additional wire being used as a sight and two levers, the
second being curved according to the trajectory of the gun. Both levers are moved
by the same slide and the act of adjusting the instrument to read the angle
subtended by an object of known height raises or lowers the additional cross wire
to the correct elevation for hitting the object.
Dated this 20th day of November 1890.
J. P. CAMPBELL.
COMPLETE SPECIFICATION.
An Improved Instrument for Measuring Angles, suitable for Judging
Distances and other purposes.
1, JAMES PALMER CAMPBELL, of Wyndham Street, in the City of Auckland,
in the Colony of New Zealand, Barrister, now residing at 1 Montague Street,
Russell Square, W.C., London, (a communication to me from abroad by Thomas
William Mayson, of Ponsonby, in the City of Auckland, New Zealand,
Draughtsman,) 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 relates to a convenient form of micrometer for measuring small
angles. In the focus of the eye piece of a telescope there is a fixed and also a
moving cross wire. The moving cross wire is connected to a lever pivotted to the
télescope, so that, as the lever is turned about its pivot the distance between the
two cross wires is varied. There is a slide upon the telescope which when moved

page_text: such bearing the cross wires of the telescope W being placed so as to fall upon the
base line the object is then again observed through the measuring telescope. The
object whose distance is to be measured will be seen at some distance apparently to
the right of its former position, next by means of the clevating and depressing
screw K the instrument is raised until the object touches the diagonal wire V.
Finally the movable wire Q is raised until it cuts the object on the diagonal
wire and the distance will then be shown on the indicator.
The instrument can also be adapted as a sight for guns. In this case there are
two moving wires the additional wire being used as a sight and two levers, the
second being curved according to the trajectory of the gun. Both levers are moved
by the same slide and the act of adjusting the instrument to read the angle
subtended by an object of known height raises or lowers the additional cross wire
to the correct elevation for hitting the object. The two cross wires are first set on
the top and bottom of the object of known height and then the gun is clevated,
until the additional wire is upon the object.
This arrangement is shown in side elevation at Figure 6. X is the additional
beam which is curved according to the trajectory of the gun. This beam is
supported in a fork at the bottom of the screw F¹ and actuates a slide Y which
carries a cross wire forming the sight. In all these cases the graduations may be
along the telescope instead of on the beam.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed 1 would state that I do
not claim generally the use of a moving and a fixed cross wire in a telescope as |
am aware that this has already been proposed but what I claim is :-
1. The combination of a telescope having a cross wire fixed in it, a pivotted
beam actuating a movable cross wire in the telescope and appliances for measuring
the angle between the axis of the telescope and the beam substantially as
described.
2. The combination of a telescope having a cross wire fixed in it, a pivotted
beam actuating a moveable cross wire in the telescope and a slide moving along the
telescope and supporting the beam there being graduations either on the beam or
along the telescope substantially as described.
3. In combination with apparatus such as is referred to in the preceding claims
a longitudinal level and a mirror for reading it substantially as described.
4. In combination with apparatus such as is referred to in the preceding claims
a curved beam actuating a second moveable cross wire in the telescope substantially
as described.
5. Instruments for measuring angles substantially as described and shown in the
drawings.
Da hot f
1001