A NEW INSTRUMENT FOR DETERMINING THE POSITION AND BEARING
Year: 1856

page_text: LETTERS PATENT to Charles Frederick Stansbury, of the American and
European Patent Offices, 67, Gracechurch Street, London, for the Inven-
tion of "A NEW INSTRUMENT FOR DETERMINING THE POSITION AND BEARING
"
Sealed the 17th October 1856, and dated the 19th April 1856.
PROVISIONAL SPECIFICATION left by he said Charles Frederick Stans-
bury at the Office of the Commissioners of Patents, with his Petition, on
the 19th April 1856.
I, CHARLES FREDERICK STANSBURY, of the American & European Patent
Offices, 67, Gracechurch Street, London, do hereby declare the nature of the
said Invention for "A NEW INSTRUMENT FOR DETERMINING THE POSITION AND
BEARING OP SHIPS AT SEA," a communication from a foreigner resident abroad,
to be as follows:-
This Invention consists in the production of a new instrument, which I call
the equatorial sextant, adapted to the determination of latitude, time, azimuth,
altitude, and declination. Such an instrument I form by combining with the
principles of construction of the common sextant equatorial and horizontal
movements, by which latitude, time, azimuth, altitude, and declination are
read directly from the graduated arcs of the instrument without computation.
The mechanical details of my Invention will be fully set forth & illustrated in
my final Specification & Drawings.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Frederick Stansbury in the Great Seal Patent Office
on the 18th October 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
FREDERICK STANSBURY, of the American and European Patent Offices,
67, Gracechurch Street, London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent bearing date the Nineteenth day of April, in the year of our Lord One
thousand eight hundred and fifty-six, in the nineteenth year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said Charles
Frederick Stansbury, Her special licence that I, the said Charles Frederick
Stansbury, my executors, administrators, and assigns, or such others as I, the
said Charles Frederick Stansbury, 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 INSTRUMENT FOR DETERMINING THE POSITION AND BEARING OF SHIPS AT
SEA," a communication from a foreigner resident abroad, upon the condition
(amongst others) that I, the said Charles Frederick Stansbury, my executors
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 Charles Frederick Stansbury, do hereby
declare the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement:-
My Invention consists in the construction of a new instrument for determin-
ing the position and bearing of ships at sea, which I denominate the equatorial
sextant, said instrument being adapted to determining latitude, time, azimuth,
and altitude, and also declination by the means herein-after described.
In the accompanying Drawings A represents the meridian circle; B, the,
latitude circle, moving inside of the meridian circle, together with its tangent
screw C, the face side of which is divided to read and set off the declination of
the celestial object, and also the latitude; D, the hour circle reading to
minutes of arc by the vernier at the end of the revolving limb E, on which

page_text: is a slotted arc F; G is the azimuth circle, at the centre of which is a conical
spindles, on which a revolving sextant I, J, K, x, is placed. I is the index
glass; J, the horizontal glass; K, the altitude arc; and L, limb and vernier
of this are to which the index glass is attached. On the back of the altitude
arc there is a small arc a and limb 6 leading from the attachment of the
horizon glass J with a vernier and tangent screw c for the purpose of adjusting
the horizon glass to the necessary correction for dip, refraction, semi-diameter,
and parallax as the observation may require. M is the declination limb, and
is set and clamped to the declination of the celestial object by its attachment
to the arc F; thus when the revolving limb E is moved over hour circle D, it
will give motion to revolving sextant I, J, K, L, a, whose index mirror will
reflect the image of the celestial object on the horizon glass, and when moved
to the local apparent time of day it will be seen in the horizon. The meridian
circle A resting on a stand S forms the main frame of the instrument, all the
other parts being connected with this circle either directly or indirectly. The
Jatitude circle B moves concentrically with and in contact with the inner
periphery of circle A, and is guided by clamps c. When properly set, it can
be clamped fast by clamp screw f and then finally adjusted by tangent screw
c, through the medium of the nut f and piece f connected with the latitude
circle. The hour circle D is firmly screwed to the arms g, g', g, projecting
from the latitude circle. The limb F with its vernier v in contact with the
divided face of circle D revolves around the centre of said circle D, the arm g'
serving as the centre bearing for its revolutions, and at the same time as a
means of adjusting the circle D to its proper place by means of the set screws
m², m². ¿ is a clamp screw to fasten the limb to the circle when properly set,
and the tangent screw h serves for its final adjustment through the medium of
nut m³ on limb E. The slotted arc F is screwed to the limb E; the piece K
moves over the slot of arc F, and can be clamped by screw d passing through
the slot. The piece K serves as a bearing for the pivot m' at the outer end
of arm n, which arm n turns about the horizontal axis of spindle 9 projecting
from the tubular standard or centre t, which latter fits over and turns about
spindle s fastened to the lower part of circle A. The azimuth circle G (con-
centric with spindle s) is fastened to circle A by clamps c mentioned above.
The centre of the circles A and B is the point where the prolonged centre line
m, m, of arm g³, the centre line l, l, of spindle q, and centre line p, p, of spindle
s intersect each other. This point of intersection is at the same time the
centre of the slotted arc F. The altitude arc K is fastened to the projection
p on the tube t, and is concentric with the central line of the horizontal
spindler, which latter is the centre of motion of limb L, which limb

page_text: carries the vernier of arc K, and has also the index glass I attached to it. The
horizon reflector J is attached to disc n', which disc is attached to disc n² on
arm by means of adjusting screws, the adjustment being for the purpose of
fixing the parallelism between the horizon and index reflectors. The disc n
turns on a centre disc projecting from the inner face of piece n³, said centre
disc being conical, so as to hold the disc n² to its bearings, it being a common
mode of construction in such cases, and others may be substituted if desired.
The piece n³ projects from the vernier a³ of the azimuth circle. The arm b
bearing at one end the vernier a', and turning upon the centre disc just
mentioned, is adjusted by set screw c attached to arc K; attached to arc K is
-the sight.a. The vernier a¹ of the azimuth circle is attached to arc K in rear
of the horizon glass. The small arc a, together with arm band set screw c,
serves for adjusting the horizon glass to the necessary correction for dip, refrac-
tion, semi-diameter, and parallax, as the observations may require. It will be
seen from the above that the parts I, J, K, L, and x form a common sextant
which revolves upon a spindle. The revolution of this sextant is produced in
the following manner :-An arm L² projects from limb L, which arm has a flat
surface e, which lies in the same plane with the centre line of spindle r. A
small block fastened to arm (which arm projects from arm n above
described), slides on and is kept in contact with said flat surface e¹ by a spring
arm e extending also from limb L. The bearing K being clamped to arc F,
extending from limb E; this bearing, and consequently the arm n, will move
about spindle q, and block e will act upon surface e¹, and cause the limb L to
move about spindle r. As the distance from spindler to spindle 7, and the
centre bearing or pivot of block are equal, the angles read off on altitude
arc K. will be exactly one half of the angles read off on the circles A and B,
thus reading as in the common sextant. y represents dark glasses; and u is the
vernier of latitude circle; and H is the vernier of the declination arc; and e, e³,
are magnifying lenses for reading the divisions of the verniers e and are K,
and verniers a¹ and arc a respectively.
DIRECTIONS FOR TAKING AN OBSERVATION.
Having set the latitude circle to a given latitude, and the declination
having been set off on the declination are by the vernier H on limb M, remove
the limb M from its attachment to limb by removing the set screw e³, and
the limb E being moved over the face of the hour circle will give motion to
the revolving sextant and azimuth vernier a¹ and altitude vernier e, and when
the celestial object is seen in the horizon, the azimuth, altitude, and time may
be read from the instrument. It will be seen that the latitude circle B serves

page_text: also as declination are when limb M is attached. L' is the zero point for
latitude, and D¹ the zero point for declination. It is obvious that this
instrument may be used as a machine for computing from altitudes taken with
the common sextant or other instruments, and when it is used for this purpose
only, the sextant attachments may be dispensed with and detached from the
instrument and the supplementary altitude arc K' substituted therefor. This
arc K¹ must be attached to spindle q, and will give the readings in whole
degrees instead of the half readings of arc K attached to spindle r.
9
Having thus fully described my equatorial sextant, what I claim under the
above in part recited Letters Patent is combining with the principles of
the common sextant equatorial and horizontal movements, substantially as
herein above set forth, for the purpose of obtaining latitude, time, azimuth,
altitude, and declination, which are read from the instrument without computa-
tion. And particularly I claim combining with the vertical spindle s the
centres q and r, and limbs L' and n, as set forth. I also claim combining
the centres 9 and r and limbs L' and n with the arc F by means of the
movable bearing e³, or its equivalent, and pivoted bearing k, as set forth. I
also claim combining the limb E, which moves over the face of the hour circle,
with the limb n, by means of the slotted arc, or its equivalent, and movable
bearing K. I also claim combining the latitude circle with the limb n by
means of the limb E, having its centre of motion in the line m, m, arc F, and
bearing k, as set forth. I also claim the supplementary arc K¹ to be attached
to spindle 9, as set forth.
In witness whereof, I, the said Charles Frederick Stansbury, have hereunto
set my hand and seal, this Eighteenth day of October, in the year of
our Lord One thousand eight hundred and fifty-six.
CHAS F. STANSBURY. (L.S.)