A New or Improved Index Clinometer or Instrument for Measuring Vertical Angles.
Year: 1888

page_text: Date of Application, 14th May, 1888
Complete Specification Left, 12th Feb., 1889
Complete Specification Accepted, 16th Mar., 1889
A New or Improved Index Clinometer or Instrument for Measuring
Vertical Angles.
I, BURNETT GREIVE HALL of Abercromby Place, Fermoy in the County of Cork,
Major, in H.M. Royal Marine Artillery, do hereby declare the nature of this invention
to be as follows:-
The Invention consists in the application of a plumb weight, capable of adjustment,
-to an index arm, whereby vertical angles can be measured, and a simple and
inexpensive instrument constructed, suitable to the requirements of military
surveying.
The application of my invention to the purpose required is shown in the accompanying
Drawings of which the following is a description.
Figs. 1 & 2 are identical in principle, and only differ in form or shape.
In the Drawing the cover of the instrument is supposed to be removed.
An Index Arm "A" is attached to a shaft which pivots at "C." To the same sbaft
is attached a counter-balancing arm "P," bent as shown to give freedom of movement
to the weight "W," attached to its lower extremity, within the limits of the case.
The weight "W" can be moved along the lower part of the arm "P" for purposes
of adjustment.
The Index Arm "A" carries at its extremity a fine needle pointer
to the axis of the shaft on which the arm pivots.
66
a
set parallel
Through the rim of the case there is an eye-hole at "E," and an opening at "L."
Also the inner rim of the case, "be," is fitted with a scale reading degrees. A fine
wire across the opening at "L." indicates the centre of the instrument from the eye-
hole at "E."
The eye at "E" can see the distant object through the opening "L." and the Index
Pointer" a; "and the latter will indicate the vertical angle of elevation or depression,
above or below the horizontal, when the centre of the instrument is properly laid for
the distant object.

page_text: said
Having now particularly described and ascertained the nature of my
invention, and in what manner the same is to be performed, 1 declare that what I
claim is,
The application of a plumb weight with an index arm to instruments for measuring
vertical angles, substantially as herein shown and described.
Dated this Twolfth day of May 1888
COMPLETE SPECIFICATION.
A New or Improved Index Clinometer or Instrument for Measuring
Vertical Angles.
I, BURNETT GREIVE HALL of Abercromby Place, Fermoy, Co. Cork, Major, Royal
Marine Artillery, 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 improvement consists in the application of a counterbalanced index arm or
pointer to the measurement of vertical angles.
The application of my invention to this purpose is shown in the accompanying
Drawings, reference being had to the letters and figures marked thereon, of which
the following is a description.
.
In Figure 1. the cover is supposed to be removed; and Figure 2. shows the
instrument complete with its cover.
«
"
"
"
An index arm A" pivots at "C" and has attached to it a counterbalancing
arm "P," which is bent in such a manner as to admit of the free movement of the
plumb weight "W" within the limits of the case, and clear of the line of sight
between "E" and "L." The lower extremity of the arm "P." is fitted with a screw
thread whereby the weight "W can be adjusted so as to retain the index Arm "A,"
when the instrument is in use, in a horizontal position. The extremity of the arm A
. carries a fine pointer a," set at right angles to it, and parallel to the axis of the
pivot "C." The arm "P" is made of greater thickness than the arm "A" in order
to counterbalance the greater length of the latter, and to bring preponderance behind
the pivot "C," so that the centre of gravity of the weight W," when the
instrument is in adjustment, may rest in front of the vertical line through the centre
of the pivot "C." This is in order to reduce vibration. "b" "e" is a scale of
legrees calculated to the radius "C" "L.". "L" is an opening with a central line or
23
"

page_text: pointer, through which objects can be seen, by direct vision, by the eye placed
at "E." The eye at "E," also, sees directly the pointer
" and the scale of
degrees """
e.
a
To ascertain the angle of elevation or depression subtended by any object, bring the
centre line, or pointer, of the opening "L" opposite the object to be observed, and the
pointer "a "of the index arm will indicate on the scale the angle sought for.
1 do not confine myself to the dimensions given in the Drawings, as the instrument
can be made, within limits, of any size; but the shape of the case here set-forth is new
for instruments of this nature, and has the advantage of combining within minimum
limits as to dimensions the maximum radius for the scale of degrees "b" "e."
رو
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. The application of Counterbalanced Index arms to instruments for measuring
vertical angles, substantially as and for the purposes and advantages herein described,
in reference to and shown in the accompanying Drawings.