Improvements in Surveying Instruments.
Year: 1890

page_text: Date of Application, 6th Dec., 1890
Complete Specification Left, 29th July, 1891-Accepted, 19th Sept., 1891
PROVISIONAL SPECIFICATION.
Improvements in Surveying Instruments.
I, THOMAS WILLIAM GOAD of Shanklin House, Bonchurch Road, North
Kensington, London, W., Civil and Mining Engineer, do hereby declare the nature
of this invention to be as follows:-
This invention relates to an improved surveying instrument adapted for use as a
hand instrument in reconnaissance or exploring work when great precision is not
required and also for surveys requiring great precision either on the surface or in
underground, mine, or other workings.
The invention consists of an improved altazimuth usable alone as above
mentioned for exploring work and in the combination thereof with the horizontal
limb or circle of a theodolite whereby to ensure the precision of the readings
necessary for more accurate work.
The ordinary pocket altazimuth comprises a combined telescope, clinometer, and
azimuth compass for ascertaining angles in altitude and in azimuth, the clinometer
and compass being contained within the opposite sides of a box or drum traversed
diametrically by the telescope.
In using this instrument, the drum must be in a vertical plane for ascertaining
angles in altitude and in a horizontal plane for ascertaining angles in azimuth and
it is necessary after sighting the station to turn the instrument from the one to the
other position in order to ascertain the combined angle or true bearing when the
station sighted is not on the same plane with the telescope.
This alteration of position of the instrument is apt to cause considerable error in
the observation and the object of this invention is, whilst retaining the portable
form of the ordinary altazimuth, to enable the compass to be accurately adjusted,
by reference to the clinometer or otherwise, to the horizontal position necessary
for the swinging of the compass card whilst the telescope is held at any angle of
elevation or depression so that both vertical and horizontal angles may be ascer-
tained without altering the position of the instrument.
For this purpose the compass box is so connected to the clinometer drum that it
can either be folded flat against the end of the same or turned to a position in
which the axis of the compass is perpendicular to that of the clinometer and the
compass is so mounted that it may be rotated about the axis of the clinometer, a
circle graduated to correspond to the clinometer scale being provided to enable the
compass to be adjusted to a horizontal position by reference to the reading of
the clinometer.
The clinometer drum is provided with the usual foot for application to a straight-
edge and adapted (when an instrument of precision is required) to be clamped to a
cradle carried by a horizontal axis mounted on the alidade movable about a vertical
axis over a graduated horizontal circle resembling the lower limb of a transit
theodolite. Any suitable form of connection may be adopted which permits of the
The axis of the cradle
easy and secure attachment and removal of the instrument.
is provided with a micrometer screw for fine adjustment in altitude. Upon the
base of the alidade are mounted two levels, and for fine adjustment in azimuth a
clamp is adapted to grip the edge of the graduated plate at any point and carries
a micrometer screw, working in a nut carried by an arm fixed to the base of the
alidade.
The instrument may thus be used as a portable hand instrument or as a transiț
'

page_text: or instrument of precision for reading the courses stadia distances and angles of
elevation or depression at the same time.
Dated this 6th day of December 1800.
T. W. GOAD.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
COMPLETE SPECIFICATION.
Improvements in Surveying Instruments.
I, THOMAS WILLIAM GOAD of Shanklin House, Bonchurch Road, North
Kensington, London, W., Civil and Mining 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 :-
"This invention relates to an improved surveying instrument adapted for use as a
hand instrument in reconnaissance or exploring work when great precision is not
required and also for surveys requiring great precision either on the surface or in
underground, mine, or other workings.
The invention consists of an improved altazimuth usable alone as above
mentioned for exploring work and in the combination thereof with the horizontal
limb or circle of a theodolite whereby to ensure the precision of the readings
necessary for more accurate work.
The ordinary pocket altazimuth comprises a combined telescope, clinometer, and
azimuth compass, for ascertaining angles in altitude and in azimuth, the clinometer
and compass being contained within the opposite sides of a box or drum traversed
diametrically by the telescope.
In using such an instrument the drum must be in a vertical plane for ascertaining
angles in altitude and in a horizontal plane for ascertaining angles in azimuth and
it is necessary after sighting the station to turn the instrument from the one to the
other position in order to ascertained the combined angle or true bearing when the
station sighted is not on the same plane with the telescope.
This alteration of position of the instrument is apt to cause considerable error in
the observation, and the object of this invention is whilst retaining the portable
form of the ordinary altazimuth to enable the compass to be accurately adjusted
by reference to the clinometer or otherwise to the horizontal position necessary for
the swinging of the compass card whilst the telescope is held at any angle of
elevation or depression so that both vertical and horizontal angles may be ascer-
tained without altering the position of the instrument.
-
For this purpose the compass box is so connected to the clinometer drum that it
can either be folded flat against the end of the same or turned to a position in
which the axis of the compass is perpendicular to that of the clinometer, and
further the compass is so mounted that it may be rotated about the axis of the
clinometer, a circle graduated to correspond to the clinometer scale being provided
to enable the compass to be adjusted to a horizontal position by référence to-the
reading of the clinometer.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein
Figure 1 is an elevation of the altazimuth combined with the theodolite limb and
stand, the compass being swung into position for use.
Figures 2 and 3 are side and end elevations of the altazimuth alone, and
Figure 4 a plan with the compass in position to be used.
Figure 5 is a detail.
The same letters of reference denote like parts in all the figures.
A is the telescope and B the clinometer, both constructed and combined in the
ordinary way. C is the compass hinged at c to a ring d so connected (as shewn in
detail section in Figure 5) to the drum D as to be revolvable stiffly thereon about

page_text: its axis and provided with an index d¹ moving upon a scale upon the periphery of
the drum D divided to correspond to the divisions of the clinometer. Thus by the
conjoint or universal pivotal motion of the compass about the hinge centre c and
about the axis of the clinometer, the compass may be quickly brought to a truly
horizontal position whatever may be the inclination of the telescope A. in viewing
the distant station (as shewn for instance in Figure 1) the horizontal adjustment of
the compass being effected by shifting the ring d until the index d' coincides on the
adjacent scale with the reading of the clinometer which indicates the inclination of
the telescope. The compass box when turned down on its hinge e closes snugly
against the ring d and so occupies no more room than in the ordinary altazimuth.
The clinometer drum is provided with the usual foot D¹ for application to a straight
edge and adapted (when an instrument of precision is required) to be clamped to a
cradle E carried by a horizontal axis e mounted on the alidade F movable about a
central vertical axis over a graduated horizontal circle G resembling the lower
limb of a transit theodolite. Any suitable form of connection may be adopted
which permits of the easy and secure attachment and removal of the instrument.
In the example a simple binding screw el is used, as shewn in dotted lines Figure 2.
The axis e of the cradle is provided with an arm 2 adapted to be clamped to it by
a screw and provided with a micrometer screw e¹ for fine adjustment in altitude.
Upon the base of the alidade F are mounted two levels H and for fine adjustment
in azimuth a clamp f¹ is adapted by means of a screw 2 to grip the edge of the
graduated plate G at any point and carries a micrometer screw f³ working in a nut
carried by an arm f fixed to the base of the alidade F. A similar clamp and
micrometer screw connects the axis of the plate G with the levelling frame K in
which it is mounted and provided with adjusting screws and means of attachment to
a tripod stand all as usual.
The instrument may thus be used as a portable hand instrument or as a transit
or instrument of precision for reading the courses, stadia, distances, and angles of
elevation or depression at the same time.
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. A pocket altazimuth in which the compass is so hinged and mounted on the
clinometer drum that its axis may either coincide with the clinometer axis or be
placed perpendicular thereto and be rotated about the latter, as and for the purpose
specified.
2. A pocket altazimuth in which the compass is hinged to a ring connected to
and revolvable upon the clinometer drum and provided with a scale graduated
to correspond to that of the clinometer, substantially as specified.
3. The combination of the herein-described altazimuth having the compass
hinged to a ring revolvable upon the clinometer drum, with the lower or horizontal
limb and stand of a theodolite, the connection of the altazimuth with the mounting
being such as to admit of its being readily detached for separate use as a hand
instrument, substantially as specified.
Unter th19 24th day of JMV 1891
Unted the 4th day of
1891
THOS. W. GOAD.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents