A NEW OR IMPROVED POCKET THEODOLITE WITH PROTRACTOR AND PLOTTING SCALES COMBINED, ALSO AN IMPROVED TRIPOD STAND FOR THE SAME.
Year: 1874

page_text: LETTERS PATENT to George Francis, of Carnarvon, in the County
of Carnarvon, Civil Engineer and Surveyor, for the Invention of
"A NEW OR IMPROVED POCKET THEODOLITE WITH PROTRACTOR AND PLOTTING
SCALES COMBINED, ALSO AN IMPROVED TRIPOD STAND FOR THE SAME.
"
Scaled the 3rd February 1875, and dated the 21st October 1874.
PROVISIONAL SPECIFICATION left by the said George Francis at the
Office of the Commissioners of Patents, with his Petition, on the
21st October 1874.
I, GEORGE FRANCIS, of Carnarvon, in the County of Carnarvon, Civil
Engineer and Surveyor, do hereby declare the nature of the said Inven-
tion for "A NEW OR IMPROVED POCKET THEODOLITE WITH PROTRACTOR AND
PLOTTING SCALES COMBINED, ALSO AN IMPROVED TRIPOD STAND FOR THE SAME," to
be as follows:—
The object of this Invention is to produce a light, handy, and useful
pocket theodolite and tripod stand at a moderate cost, and to combine
with the theodolite a protractor and scales for plotting or laying down

page_text: For taking horizontal angles the instrument must rest on the stand
directly under the moveable limb, and the fixed limb (carrying the
sights) put in line with one of the objects subtending the required
angle (both limbs being close together), the fixed limb is then moved
into line with the second object, and the angle subtended by the said
two objects will be shown by the distance between the opened limbs.
In the stand below the said revolving table is a joint by means of which
the instrument can be turned "on edge" for the purpose of taking
vertical angles, which are shewn, as before stated, for horizontal angles;
also on the back of the instrument the angles will be shewn in inches to
the fathom by a circular scale.
In taking the angle of what is termed the "underlie of a heading,"
or the dip of strata, or of an incline or gradient, the theodolite is
simply placed thercon on its lower edge, the moveable limb is then
raised to the horizontal level, which is indicated by the spirit level fixed
thereon. The angle and the inches to the fathom thereof are read off as
before stated.
For magnetic surveying, or what is termed "dialing," the instrument
after being properly adjusted on its stand is used exactly as the ordinary
dials, the north point of the compass being by preferonce directly in
front.
The instrument can also be used for ordinary levelling by first setting
it perfectly horizontal by the aid by the aid of the spirit levels thercon
and the ball-and-socket joint in the stand; a forward or first observation
is then taken through perforations formed in the upper part of the sights
for that purpose, the instrument is then reversed, having first loosened
the clamping screw of the said revolving table, when a back or second
sight is taken as usual.
When not in use the instrument can be carried in the pocket, and the
tripod, which is proportionally light, when closed is round and forms a
convenient walking stick, the upper part being covered with a metal
can
·

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said. George Francis in the Great Seal Patent Offico
on the 20th April 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
FRANCIS, of Carnarvon, in the County of Carnarvon, Civil Engineer and
Surveyor, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-first day of October, in the
year of our Lord One thousand eight hundred and seventy-four, in
the thirty-eighth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said George Francis, Her
special license that I, the said George Francis, my executors, admi-
nistrators, and assigns, or such others as I, the said George Francis,
my executors, administrators, and assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for
"A NEW OR IMPROVED POCKET THEODOLITE WITH PROTRACTOR AND PLOTTING
SCALES COMBINED, ALSO AN IMPROVED TRIPOD STAND FOR THE SAME," upon the
condition (amongst others) that I, the said George Francis, my execu-
tors or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and ascertain
the nature of the said Invention, and in what manner the same was to
be performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said George Francis, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :—
The object of this Invention is to produce a light, handy, and useful
pocket theodolite and tripod stand at a moderate cost, and to combine
with the theodolite a protractor and other scales for plotting or laying
down on paper the angles and other details taken, measured, or surveyed
by the instrument, and for general purposes.

page_text: for taking horizontal angles, and (c¹) on the edge of one of the said arms
for taking vertical angles either of altitude or depression, see Figures 1
and 4; a spirit level d, d, is fixed on the upper surface of each arm A, B,
at right angles to each other, and also one d² on the side or edge of cach
arm A, B, for the purpose of setting the instrument to the true hori-
zontal level and to secure general accuracy. In the upper part of the
circular end of the arm A is a sunk recess e, in the centre of which a
magnetic needle e¹ is pivotted or balanced, in which recess e the cardinal
points of the compass are marked and are divided into degrees (see
Figure 1) for the purpose of underground surveying, or what is technically
termed dialling.
.
1
To facilitate the adjustment of the instrument when placed on its
stand the latter is provided with a ball-and-socket joint or movement g,
which joint can be tightened or fixed at will by screwing the upper
part of the said socket on the lower part ×¹ thereof; the said upper
part can be detached by unscrewing it, when the ball can be removed
if required, see Figure 6; or the said ball-and-socket joint may be
tightened by a clamping screw in the usual way, the socket being
made in two divisions vertically instead of horizontally, as in Figure 6;
under the ball-and-socket joint at i there is a rotary horizontal move-
ment for the purpose of taking the "underlie" (herein-after described)
direction from one stand point.
in any
On the upper surface of the arms A, B, is a scale of from 1 to 60 feet
to the inch, and a scale of equal parts for reference and general purposes,
see Fig. 1. Also on the outer side or edge of the fixed arm A, and on
both the square ends and the round end of the instrument, is a pro-
tractor scale for plotting angles; or the said scale may be formed on the
inner half of the circular end and be used when the arms are fully open,
see Figure 3.
When using the instrument it is fixed on a tripod stand by means of
a bevilled projection j¹ on the top thereof attached to the upper plate of
a revolving table j formed of two parallel plates, see Figure 6, fitting
and sliding in a similarly shaped groove cut or formed in the under side
of the theodolite and across it, making together what is termed a dovetail
joint; or the theodolite may be screwed to the neck f of the ball of the
ball-and-socket joint, a groove or opening f' in the side of the said socket
being cut or formed to allow the said neck f to be turned down hori-

page_text: zontally, as shewn in red in Figure 7. By either of these means the
theodolite can be turned on edge for the purpose of taking vertical
angles either of altitude or depression, for which purpose the instru-
ment is turned on edge or placed vertically, as before described, the
fixed arm A is brought to the horizontal level in the usual way, the
moveable arm B is then raised until the two sights c', Figures 1 and 4,
are in line with the object above or below, as the case may be, the angle
thus taken being shewn, as herein-after stated, for horizontal angles;
also on the back of the instrument such angles will be shewn in inches
to the fathom by a semicircular graduated scale ; also the length of
the base of such angle is shown by the scale in inches to the fathom,
see Figure 2.
On each arm A, B, of the instrument is fitted parallel to the sides of .
the said arms a pair of folding sights c for the purpose of taking hori
zontal angles. To do this the fixed arm A is put in line with one of the
objects subtending the required angle, the moveable arm B is then
brought or moved into line with the second object and the angle sub-
tended by the said two objects will be shown by the distance between
the open arms recorded or shown on the scale a and vernier b to the one-
twentieth (") part of a degree.
In taking what is termed the "underlic of a heading," or the dip of
strata, or of an incline, or gradient, the theodolite is simply placed
thereon on its lower edge, the moveable arm B is then raised to tho
horizontal level, which is indicated by the spirit level & fixed thercon,
see Figure ; the angle in degrees and in inches to the fathom are
shown, as herein-before stated.
For magnetic surveying, or what is termed "dialling" the arms of
the instrument are opened to form a straight line (180°); the outer
sight c on each arm is then raised and the requisite observations made
or taken precisely as is donc with the ordinary dial, the north point of
the compass being directly in front.
My improved theodolite can also be used for ordinary levelling by
first setting it perfectly horizontal by the aid of the spirit levels a, d²,
and the ball-and-socket joint; the usual back and fore sights or
observations are made or taken through perforations m formed in the
upper part of the said sights for that purpose, see Figure 1.

page_text: When not in use the instrument can be carried in the pocket, and the
tripod, which is proportionally light, when closed is round and forms a
convenient walking stick, the upper part being covered with a metal
cap.
Having thus fully described and ascertained the nature of my said
Invention, and the method of performing the same, I wish it to be
understood that I do not claim any of the parts per se of my said instru-
ment as new, neither do I confine myself to the dimensions of the instru-
ment now illustrated, nor of the details thereof; but I claim as my
Invention, and desire to secure by the herein-before mentioned in part
recited Letters Patent, the combination and arrangement of the several
parts forming my said improved theodolite, substantially as hercin
described and shown in the Drawing.
In witness whereof, I, the said George Francis, have hereunto
set my hand and seal, this Nineteenth day of April, in the year
of our Lord One thousand eight hundred and seventy-five.