Two In- STRUMENTS WHEREBY THE LATITUDE, LONGITUDE, AND MAGNETIC VARIATION AT SEA OB ON SHORE MAY BE OBTAINED
Year: 1794

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PATRICK
ROONEY NUGENT, late Cheif Surveyor of Crown Lands in the Island of
Cape Breton, in North America, but now of Gray's Inn, in the County of
Middlesex, Esquire, send greeting.
WHEREAS His most Excellent Majesty King George did, by His Letters
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Eighteenth day of March, in the thirty-fourth year of His reign, givo
and grant unto me, the said Patrick Rooney Nugent, His special licence
that I,. the said Patrick Rooney Nugont, during the term of years therein
mentioned; should-and lawfully might use, exercise, and vend, within England,
Wales, and thic Town of Berwick-upon-Tweed, my Invention of "Two In-
STRUMENTS WHEREBY THE LATITUDE, LONGITUDE, AND MAGNETIC VARIATION AT SEA
OB ON SHORE MAY BE OBTAINED;" in which Letters Patent is contained a proviso
obliging me, the said Patrick Rooney Nugent, by an instrument in writing
under my hand and seal, to cause a particular description of the nature of
my said Invention, and in what manner the same is to be performed, to be
inrolled in His Majesty's High Court of Chancery within one calendar month
next after the date of the said recited Letters Patent, as in and by the same,
relation being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Patrick Rooney Nugent, do hereby declare that my said Invention is used in
manner following (that is to say) :-
The instruments as delineated on the margin hereof consist, first, of an
universal reflecting septant, sextant, oxtant, or quadrant of a glass tubb and

page_text: bubble, and of a pendulum for taking altitudes without an horizon; and,
secondly, of a steering or universal azimuth compass. The arch of the septant
contains two hundred reflected degrees, and is divided and numbered from
the centre, at which is placed 0 degrees; from thence to either extremity of
the circle it is marked or numbered regularly 5, 10, 15, 20, 25, 30, &c.,
to 100. This instrument hath an index with a vernier or nonices, which is
also divided and numbered from its middle or center, and so as to read either
way. The heads of the clamp screw and tangent screw, on the end of the
index, are both on top; the former being opposite the middle of the nonices,
and the head of the latter next the observer, in case there is an handle at the
back of the instrument as usual, otherwise they are better as they aro com-
mouly fixt and made. On the head of the index is a circular plate, confined
to the index by means of two scutcheons placed on or to the centre, the
lowermost of which is a squaro and the other a round scutcheon; or it may
be confined by any other method judged best. The head of the index, instead
of being cast or filed round, hath a small projection at the head thereof of about
half an inch, and of the width of about three fourths of an inch, which projec-
tion is a little distance before the center line or direction of the bar of the index.
Upon this projection is fixed an endless screw, by means of a clamp screwed
down to the former projection, which screw acts in a grove or sort of fine
rackwork, cut or made out of the upper edge of the circular plate already
mentioned, by a screw engine, to answer the threads of the endless screw
aforesaid, and by which endless screw the plate and the several matters thereon,
herein-after described, aro horizontally adjusted as need may require. The
head of the endless screw aforesaid is placed next the observer. On the plate
before described is fixed or fastened two speculums or glasses, the lower glass
of which is made fast at right angles to the plane of the instrument, as usual
in Hadley's sextants; but it will be more form to have this glass slide into a
dovetail frame or solid case, having a grove made in it for the glass to slido
upwards into, and a small slip of brass soldered or made fast with screws to
the head of the aforesaid solid frame or case, to confine and protect the upper
odge of the glass, and any method judged best to stendy it there. The upper
glass is confined in a clip or case open at the lower end, a slip of brass of
about equal size with the glass, and having four pius or points near the angles
of its ends, to prevent the silvering of the glass from being injured, and having
a case which projects therefrom upwards about the same height as the thick-
ness of the glass. This slip or piece of brass is introduced with the glass
thereon, or in front of it, up into the former case or clip, and both confined
therein by means of two small screws partly introduced through the back of

page_text: the aforesaid clip or case. This glass acts upon two centers made fast or
soldered to the sides of its frame or clip, and which centers pass through and
are confined in two pieces fastened with screws, or otherwise, to the sides of
the lower frame, and to a part of its back if found necessary. The middle
or center of these centers are to be opposite the horizontal line herein-aftei
mentioned to be drawn on the back of this glass. The uppermost of those
pieces (when the instrument is adjusted for taking altitudes or angles by
double reflection) hath a semicircular broad part at the upper part thereof,
(which projects backwards from the front of the glass), of at least eight
tenths of an inch radius, which must be divided into reflected degrees, so far
as to allow the observer, by assistance of the vernier belonging thereto, to read
of of about one hundred degrees. These degrees, as well as the vernier
divisions, are to be numbered from the observer when he looks at the facc
or front of the glass, and to commence together when the glass is adjusted
perpendicular to the plane of the instrument. The vernier or nonices just
mentioned is fixed by means of screws to the upper part of the frame of the
glass. The motion of this glass on its centers is made by means of a tangent
screw placed opposite to the center of the glass, the shank part or head of
which screw acts in a poppet fastened into the upper part of a small arm or
other contrivance made fast to the back part of the frame, or to the case of
the frame of the lower glass, by means of screws or soldering, no part of which
arm must extend higher than the upper edge of the frame of the lower glass.
The point parts of said screw is made fast or confined by means of another
small poppet, fastened into a picce made fast to the upper part of the frame
of the glass; or the tangent screw may be inverted, or its motion may be given
by an endless screw working in a rack, cut out of the upper edge of the semi-
circular piece aforesaid, or by any other of the various methods already suffi-
ciently well known. The horizon glass hath two silvered parts, and an open
parallel space to the plane of the instrument between them; the lower part
is used with the lower index glass in all respects as Hadley's horizon and
index glasses are, but the upper is to be used with the upper index glass.
This horizon glass hath need of no horizontal adjustment, but its vertical
adjustment may be by any of the methods already sufficiently known, or such
other found most convenient. The back surfaces of the lower and upper glass
are equally divided by a perpendicular line drawn on them. The back surface
of the upper glass is also equally divided by another line drawn horizontally
thereon; the reflexion of this latter line, when the glass is vertically adjusted,
defines the lower part of the upper silvering of the horizon glass, and the
reflexion of the upper edge of the lower index glass will define the upper edgo

page_text: of the lower silvered part of the horizon glass; the space between ought to lo
unsilvered, and the lower glass ought to be mado so small and the upper
glass so large as to admit this space to be sufficient for all observations to
be made with this instrument. The sizes of the glasses hereby described will
be therefore nearly as follows:-Cower index glass, one and three fourths
inches in width by one inch in heighth; upper index glass, one and three
fourths inches in width by eight & one half tenths of an inch in height;
hoight of the lower part of the silvering of the horizon glass, six tenths of an
inch height of the upper silvered part, four tenths of an inch, and the unsilvered
space between, threo tenths of an inch; as to the width of the horizon glass,
it should not exceed one inch and two tenths of an inch. The situation of
the horizon glass and telescope or plane sight are in a great manner discre
tionary, but the most convenient and useful in a twelve-inch instrument of
this kind will be nearly as follows: The telescope four inches and seven tenths
of an inch from the center, and the horizon glass five inches and six tenths
of an inch; they must be otherwise so placed as not to interrupt the motion
of the index to the reading off the divisions to the end of the arch. The
telescope and its adjustment are the same as is usual, save that there must
be two shades placed therein, to protect the eyes from the lustre of the sun
in taking its altitude without an. horizon or a back observation, and that it
should adjust so high as the upper part of the upper index glass. To tako
an altitude without an horizon by this instrument there are two methods, both
of or on the same principles, namely, that of gravitation. The first is by a
perfectly circular cylindrical concave glass tube, the most conveniant size of
which for the instrument and observer will be found about seven and an half
incles radius, one fifth of an inch concavity, and one fifth of an inch thick;
this tube, to be cased with brass, excepting about threo tenths of an inch of
the surface next the center, which should be a little more in length than a
quarter of a circle, is to be so placed when used, that the lower part or sur-
face of its concavity form a perfect portion of a circle in respect to the center
of the instrument, and the height of its upper surface be about an inch and
a quarter from the plane of the instrument; and when its inner surface or
concavity is perfectly clear, a bubble of thoroughly puro clear quicksilver or
mercury is put and used therein. When a pendulum is designed for this
instrumont, either the case of the frame of the lower index glass must be
made sufficiently thick, or another plate of little more than semicircular form
is placed over the circular plate already described, which plate must be about
one fifth of an inch in thickness; this plate, or tho caso aforesaid, must be
so hollowed out in front as to permit the free vibrations of the pendulum in

page_text: taking altitudes from the horizon up to the zenith; the center of the instru-
ment which before only extended even with the upper surface of the circular
plate already mentioned, must in this case extend through the base of the
frame of the lower index glass, or through the nearly semicircular plate just
described. This additional or increased length of center supports the pen-
dulum, which is best made in two parts, the shorter of which, of about three
inches in length, always to remain on the center, and the other part to bo
occasionally attached thereto by means of a finger screw and two steady pins.
This part last mentioned hath a semi-globular ball attached to its extreme under
end bejond the arch of the instrument, and on the flat upper face of which
slides off and on occasionally a vertical plane slide of about one and an half
inch in height and six tenths of an inch wide. On the middle of this slide is
drawn a line, which line, when the index is set to 0, and the instrument
adjusted for taking altitudes without au horizon, and the observer looks at the
horizon, he should by single reflection perceive in the under index glass level.
with the surface of the sea. Withinside or near the center of the instru-
ment than the semi-ball aforesaid, and on the under surface of the pen-
dulum, is fixed four friction rollers, in two small brass pieces; these are to
play freely on the further part from the center of the arch of the instrument,
two over and two under. The whole mounting herein already described,
brass and glasses, may be placed as already set forth on any arch whatever,
whether of a sextant or quadrant, but the most conveniant lesser size will be
that of the universal reflecting octant. This instrument contains an arch of
about one hundred and ten degrees, but it is not divided or figured from the
center as the septant already described is, but from a little distance before
the limbs backwards and forwards. Thus the first space of ten or more
degrees of divisions, on the lower line next the observer, must be marked
backwards 0, 5, 10, &c.; then the said lower line is to be regularly figured
forwards from the aforesaid 0, or the observer, 5, 10, 15, 20, &c., to 100, or as
far as the arch extends; over the 100 just mentioned is marked 10, then 5,
then 0, which 0 will fall over the 90' of the former, numbering them
5, 10, 15, 20, &c., to 100, or as far as the arch runs, which 100 will fall over
the 10 backward numbering of division first mentioned; by this means the
degrees within the two 90' are made the complements of each other; then, by
setting the beginning of the vernier divisions to 0 on either end of the arch,
the index glasses are adjusted to the horizon glass by means of the endless
screw and plate already described. But altitudes without an horizon cannot be
conveniently taken near the horizon by means of the glass tube and bubble

page_text: aforesaid, nor by means of the pendulum applied to this instrument, except so
far as the glass tubo extends over the face of the instrument, or that the
pendulum can freely vibrate or traverse. The method of taking altitudes
without an horizon by either, is as follows:-The glass tube or pendulum
being placed as before mentioned, set the beginning of the vernier divisions
to the near 90 on the septant, or to the nearest 0 on the octant; screw back
the upper glass so as to allow suflicient space for observation between it and
the upper edge of the lower glass, then direct the line of vision of the telescope
or plane right to the center line of the lower speculum, by means of the end-
less screw already described; adjust the lower speculum at right angles to the
line of vision; so is the instrument adjusted; look directly over the perpen
dicular line drawn in the under glass at any object; move the index until
such time as the bubble aforesaid or the line drawn in the vertical plane
slide by single reflection in the upper edge of the lower glass is exactly hori-
zontal with the center of such object seen by direct vision over the said glass,
and the index will then show the altitude on the septant, or its zenith dis-
tance on the lower numbering of division on the octant. It hath been before
observed, that the lower index glass on either of these instruments is used
in the same manner as Hadley's sextant; but there are other uses to which
it may be applied in these instruments; thus, to take a back observation, set
the beginning of the vernier divisions to 0 on the septant, or 90 on the lower
figuring of divisions of the octant, and adjust the lower speculum at right
angles to the line of vision of the telescope, as before described for taking au
altitude without an horizon. Let the observer turn his back to the sun, and
look directly over the perpendicular line drawn in the under glass to the
surface of the sea before him, then drawing the index gently to him, until by
single reflection he brings the image of the sun to the horizon, the index will
then shew its altitude, proper allowance being made for his semi-diameter and
refraction on the septant, or its zenith distance on the lower figuring of the
divisions of the octant. The great and universal use of the upper glass is,
to measure any sort of other distances at the pleasure of the observer, as no
fixed glass can possibly measure other than direct distances or angles; but its
uses being so manifold in measuring horizontal or other distances between
objects of unequal altitudes, in taking the transits of objects at sea, in finding
the variation of the compass, and the latitudo and longitude of places, that it
would require by far too much explanation to be confined in a Specification.
Here it must be carefully attended to, that if any person or persons who may
chuse to order an instrument of the aforesaid described Invention, but not

page_text: requiring to take altitudes without an horizon nor a back observation, that
in such case all that is necessary is, that these two index glasses (or one as
herein-after described) be placed on the same kind of index and plate and in
the same manner as is usually done in fixing one erect glass on Hadley's sex-
tant, and that the horizon glass have both an horizontal and vertical adjust-
ment. The index glass just alluded to is made after the same manner as tho
upper glass already described; it hath its motion on its center by a tangent
screw, the shank or part near the head of which acts in a poppet made
fast into the upper part of a small arm or other contrivance made fast to
its base by screws or soldering. The point of said screw is made fast or
confined by means of another small poppet affixed into a pieco made fast near
the upper part of the frame (or its motion may be given by any of the other
methods already set forth), it hath a semicircular pieco and a nonices, as the
aforesaid described upper glass hath; it hath morcover on the inner part of
the back of its nonices, if its motion is given by means of a tangent screw as
already described, a small spring and tightening screw to steady it the moro
perfectly in any position, by pressing the spring by means of the tightening
screw aforesaid to the inner surface or back of its semicircular piece. This
single universal reflecting index glass, with an horizon glass silvered in two
parts, or in one part only, will perform all that both the aforesaid index
glasses will; for, when it is adjusted perpendicular to the plane of the instru-
ment, it will perform as an Hadley's sextant glass, and when it is reclined
backwards or forwards it will perform as the upper glass already described.
The future different make therefore of these instruments doth entirely depend
upon the different dispositions or choice of different persons, whilst the Inven-
tion remains the same, to wit: two index glasses instead of one as is usual,
and the upper glass having a motion on its axis or centers, to these must
belong a double-silvered horizon glass, as already described, one index glass,
but not fixed as usual, having a motion on its axis or centers, and to which,
as being but one glass, an horizon glass silvered in one part only, will be
sufficient, a circular glass tube or a pendulum, such as herein already
described, and which, by single reflection, obtains altitudes without an horizon,
the size of the instruments, and manner of numbering the divisions on their
arches, with other particulars herein already set forth these are the subjects
of the Invention. And as to the method of giving the motions already stated,
the difference of opinion of different workmen is of little avail in point of
nautical ascertainments, for if the motion is any how given by steady means,
it is perfectly sufficient.

page_text: The steerling or universal azimuth compass is made thus:-The height
of the pan or kettle for a compass of eight inches diameter is about five
inches; an aperturo. of. forty-five degrees horizontal width, and about one
inch and an half in height, is made or cut out of the side of the kettle
aforesaid, directly opposite cach other, one half or one side and the other
half on the other side of each side of the shoulders or axis of the pan,
and immediately above them two plain sights of about one and an half inch
high, six tenths of an inch wide, and having an aperture in each of about
three tenths of an inch in width, and in the center of which is fixed a hair
or silk thread. These sights are to be firmly fixed by screws or dovetail, so
that the threads or hairs aforesaid will be exactly opposite to the north and
south points of the card or needle. The apertures of the kettle or pan already
described are to be glazed with glass or ising-glass, to prevent the wind and
weather disturbing the motion of the card.
To find the magnetic variation by this compass the method is as follows:-
Placo the. beginning of the vernier divisions to 0 on the septant, or to 0 on
ono end or other of the octant, as the case may require. See that the
horizon glass and the index revolving glass are well adjusted together; look
directly up at the sun, or moon, or star, through the unsilvered part of the
horizon glass,. by means of the tangent screw or endless screw, or other
method adopted for giving the glass its motion on its centers, being the
sun, moon, or star, down to the horizon; then case the tightening screw, and
.bring the sun, moon, or star from the right or left, as the caso may be, by
reflexion in the horizon glass to the line of coincidence of the threads scen
by direct vision through the unsilvered part of the horizon glass, and the
index will then shew the magnetic bearing or azimuth, which, when compared
to the true azimuth, will determine the variation.
In witness whereof, I have hereunto set my hand and seal, the Seventh
day of April, in the year of our Lord One thousand seven hundred
and ninety-four

page_text: AND BE IT REMEMBERED, that on the Ninth day of April, in the
year of our Lord 1794, the aforesaid Patrick Rooney Nugent came before
our said Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stampt according to
the tenor of the Statutes made for that purpose.

page_text: INUGENT'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PATRICK
ROONEY NUGENT, lato Cheif Surveyor of Crown Lands in the Island of
Cape Breton, in North America, but now of Gray's Inn, in the County of
Middlesex, Esquire, send greeting.
"
WHEREAS His most Excellent Majesty King George did, by His Letters
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Eighteenth day of March, in the thirty-fourth year of His reign, give
and grant unto me, the said Patrick Rooney Nugent, His special licence
that I, the said Patrick Rooney Nugent, during the term of years therein
mentioned; should and lawfully might use, exercise, and vend, within England,
Wales; and the Town of Berwick-upon-Tweed, my Invention of "Two. In-
STRUMENTS WHEREBY THE LATITUDE, LONGITUDE, AND MAGNETIC VARIATION AT SEA
OR ON SHORE MAY BE OBTAINED;" in which Letters Patent is contained a proviso
obliging me, the said Patrick Rooney Nugent, by an instrument in writing
under my hand and seal, to cause a particular description of the nature of
my said Invention, and in what manner the same is to be performed, to be
inrolled in His Majesty's High Court of Chancery within one calendar month
next after the date of the said recited Letters Patent, as in and by the same,
relation being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Patrick Rooney Nugent, do hereby declare that my said Invention is used in
manner following (that is to say) :-
The instruments as delineated on the margin hereof consist, first, of an
universal reflecting septant, sextant, oxtant, or quadrant of a glass tubb and

page_text: bubble, and of a pendulum for taking altitudes without an horizon; and,
secondly, of a steering or universal azimuth compass. The arch of the septant
contains two hundred reflected degrees, and is divided and numbered from
the centre, at which is placed 0 degrees; from thence to either extremity of
the circle it is marked or numbered regularly 5, 10, 15, 20, 25, 30, &c.,
to 100. This instrument hath an index with a vernier or nonices, which is
also divided and numbered from its middle or center, and so as to read either
way. The heads of the clamp screw and tangent screw, on the end of the
index, are both on top; the former being opposite the middle of the nonices,
and the head of the latter next the observer, in case there is an handle at the
back of the instrument as usual, otherwise they are better as they are com-
monly fixt and made. On the head of the index is a circular plate, confined
to the index by means of two scutcheons placed on or to the centre, the
lowermost of which is a square and the other a round scutchicon; or it may
be confined by any other method judged best. The head of the index, instead
of being cast or filed round, hath a small projection at the head thereof of about
half an inch, and of the width of about three fourths of an inch, which projec-
tion is a little distance before the center line or direction of the bar of the index.
Upon this projection is fixed an endless screw, by means of a clamp screwed
down to the former projection, which screw acts in a grove or sort of fino
rackwork, cut or made out of the upper edge of the circular plate already
mentioned, by a screw engine, to answer the threads of the endless screw
aforesaid, and by which endless screw the plate and the several matters thereon,
berein-after described, are horizontally adjusted as need may require. The
head of the endless screw aforesaid is placed next the observer. On the plate
before described is fixed or fastened two speculums or glasses, the lower glass
of which is made fast at right angles to the plane of the instrument, as usual
in Hadley's sextants; but it will be more form to have this glass slide into a
dovetail frame or solid case, having a grove made in it for the glass to slide
upwards into, and a small slip of brass soldered or made fast with screws to
the head of the aforesaid solid frame or case, to confine and protect the upper
edge of the glass, and any method judged best to steady it there. The upper
glass is confined in a clip or case open at the lower end, a slip of brass of
about equal size with the glass, and having four pins or points near the angles
of its ends, to prevent the silvering of the glass from being injured, and having
a case which projects therefrom upwards about the same height as the thick-
ness of the glass. This slip or piece of brass is introduced with the glass
thereon, or in front of it, up into the former case or clip, and both confined
therein by means of two small screws partly introduced through the back of

page_text: the aforesaid clip or case. This glass acts upon two centers made fast or
soldered to the sides of its frame or clip, and which centers pass through and
are confined in two pieces fastened with screws, or otherwise, to the sides of
the lower frame, and to a part of its back if found necessary. The middle
or center of these centers are to be opposite the horizontal line herein-after
mentioned to be drawn on the back of this glass. The uppermost of those
pieces (when the instrument is adjusted for taking altitudes or angles by
double reflection) hath a semicircular broad part at the upper part thereof,
(which projects backwards from the front of the glass), of at least eight
tenths of an inch radius, which must be divided into reflected degrees, so far
as to allow the observer, by assistance of the vernier belonging thereto, to read
of of about one hundred degrees. These degrees, as well as the vernier
divisions, are to be numbered from the observer when he looks at the face
or front of the glass, and to commence together when the glass is adjusted
perpendicular to the plane of the instrument. The vernier or nonices just
mentioned is fixed by means of screws to the upper part of the frame of the
glass. The motion of this glass on its centers is made by means of a tangent
screw placed opposite to the center of the glass, the shank part or head of
which scrow acts in a poppet fastened into the upper part of a small arm or
other contrivance made fast to the back part of the frame, or to the case of
the frame of the lower glass, by means of screws or soldering, no part of which
arm must extend higher than the upper edge of the frame of the lower glass.
The point parts of said screw is made fast or confined by means of another
small poppet, fastened into a piece made fast to the upper part of the frame
of the glass; or the tangent screw may be inverted, or its motion may be given
by an endless screw working in a rack, cut out of the upper edge of the semi-
circular piece aforesaid, or by any other of the various methods already suffi-
ciently well known. The horizon glass hath two silvered parts, and an open
parallel space to the plane of the instrument between them; the lower part
is used with the lower index glass in all respects as Hadley's horizon and
index glasses are, but the upper is to be used with the upper index glass.
This horizon glass hath need of no horizontal adjustment, but its vertical
adjustment may be by any of the methods already sufficiently known, or such
other found most convenient. The back surfaces of the lower and upper glass
are equally divided by a perpendicular line drawn on them. The back surface
of the upper glass is also equally divided by another line drawn horizontally
thereon; the reflexion of this latter line, when the glass is vertically adjusted,
defines the lower part of the upper silvering of the horizon glass, and the
reflexion of the upper edge of the lower index glass will define the upper edgo

page_text: of the lower silvered part of the horizon glass; the space between ought to be
unsilvered, and the lower glass ought to be made so small and the upper
glass so large as to admit this space to be sufficient for all observations to
be made with this instrument. The sizes of the glasses hereby described will
be therefore nearly as follows:-Cower index glass, one and three fourths
inches in width by one inch in heighth; upper index glass, one and three
fourths inches in width by eight & one half tenths of an inch in height;
height of the lower part of the silvering of the horizon glass, six tenths of an
inch: height of the upper silvered part, four tenths of an inch, and the unsilvered
space between, three tenths of an inch; as to the width of the horizon glass,
it should not exceed one inch and two tenths of an inch. The situation of
the horizon glass and telescope or plane sight are in a great manner discre-
tionary, but the most convenient and useful in a twelve-inch instrument of
this kind will be nearly as follows: The telescope four inches and seven tenths
of an inch from the center, and the horizon glass five inches and six tenths
of an inch; they must be otherwise so placed as not to interrupt the motion
of the index to the reading off the divisions to the end of the arch. The
telescope and its adjustment are the same as is usual, save that there must
bo two shades placed therein, to protect the eyes from the lustre of the sun
in taking its altitude without an horizon or a back observation, and that it
should adjust so high as the upper part of the upper index glass. To take
an altitude without an horizon by this instrument there are two methods, both
of or on the same principles, namely, that of gravitation. The first is by a
perfectly circular cylindrical concave glass tube, the most conveniant size of
which for the instrument and observer will be found about seven and an half
inches radius, one fifth of an inch concavity, and one fifth of an inch thick;
this tube, to be cased with brass, excepting about three tenths of an inch of
the surface next the center, which should be a little more in length than a
quarter of a circle, is to be so placed when used, that the lower part or sur-
face of its concavity form a perfect portion of a circle in respect to the center
of the instrument, and the height of its upper surface be about an inch and
a quarter fron the plane of the instrument; and when its inner surface or
concavity is perfectly clear, a bubble of thoroughly pure clear quicksilver or
mercury is put and used therein. When a pendulum is designed for this
instrument, either the case of the frame of the lower index glass must be
made sufficiently thick, or another plate of little more than semicircular form
is placed over the circular plate already described, which plate must be about
one fifth of an inch in thickness; this plate, or the case aforesaid, must be
to hollowed out in front as to permit the free vibrations of the pendulum in

page_text: aking altitudes from the horizon up to the zenith; the center of the instru-
nent which before only extended even with the upper surface of the circular
late already mentioned, must in this case extend through the base of the
rame of the lower index glass, or through the nearly semicircular plate just
lescribed. This additional or increased length of center supports the pen-
Bulum, which is best made in two parts, the shorter of which, of about three
inches in length, always to remain on the center, and the other part to bo
occasionally attached thereto by means of a finger screw and two steady pins.
This part last mentioned hath a semi-globular ball attached to its extreme under
end bejond the arch of the instrument, and on the flat upper face of which
slides off and on occasionally a vertical plane slide of about one and an half
inch in height and six tenths of an inch wide. On the middle of this slide is
drawn a line, which line, when the index is set to 0, and the instrument
adjusted for taking altitudes without an horizon, and the observer looks at the
horizon, he should by single reflection perceive in the under index glass level
with the surface of the sea. Withinside or near the center of the instru-
ment than the semi-ball aforesaid, and on the under surface of the pen-
dulum, is fixed four friction rollers, in two small brass pieces; these are to
play freely on the further part from the center of the arch of the instrument,
two over and two under. The whole mounting herein already described,
brass and glasses, may be placed as already set forth on any arch whatever,
whether of a sextant or quadrant, but the most conveniant lesser size will be
that of the universal reflecting octant. This instrument contains an arch of
about one hundred and ten degrees, but it is not divided or figured from the
center as the septant already described is, but from a littlo distance before
the limbs backwards and forwards. Thus the first space of ten or more
degrees of divisions, on the lower line next the observer, must be marked
backwards 0, 5, 10, &c.; then the said lower line is to be regularly figured
forwards from the aforesaid 0, or the observer, 5, 10, 15, 20, &c., to 100, or as
far as the arch extends; over the 100 just mentioned is marked 10, then 5,
then 0, which 0 will fall over the 90' of the former, numbering them
5, 10, 15, 20, &c., to 100, or as far as the arch runs, which 100 will fall over
the 10 backward numbering of division first mentioned; by this means the
degrees within the two 90' are made the complements of each other; then, by
5 setting the beginning of the vernier divisions to 0 on either end of the arch,
the index glasses are adjusted to the horizon glass by means of the endless
-screw and plate already described. But altitudes without an horizon cannot be
conveniently taken near the horizon by means of the glass tube and bubblo

page_text: aforesaid, nor by means of the pendulum applied to this instrument, except so
far as the glass tube extends over the face of the instrument, or that the
pendulum can freely vibrate or traverse. The method of taking altitudes
without an horizon by either, is as follows:-The glass tube or pendulum
being placed as before mentioned, set the beginning of the vernier divisions
to the near 90 on the septant, or to the nearest 0 on the octant; screw back
the upper glass so as to allow sufficient space for observation between it and
the upper edge of the lower glass, then direct the line of vision of the telescope
or plane right to the center line of the lower speculum, by means of the end-
less screw already described; adjust the lower speculum at right angles to the
line of vision; so is the instrument adjusted; look directly over the perpen-
dicular line drawn in the under glass at any object; move the index until
such time as the bubble aforesaid or the line drawn in the vertical plane
slide by single reflection in the upper edge of the lower glass is exactly hori-
zontal with the center of such object seen by direct vision over the said glass,
and the index will then shew the altitude on the septant, or its zenith dis-
tance on the lower numbering of division on the octant. It hath been before
observed, that the lower index glass on either of these instruments is used
in the same manner as Hadley's sextant; but there are other uses to which
it may be applied in these instruments; thus, to take a back observation, set
the beginning of the vernier divisions to 0 on the septant, or 90 on the lower
figuring of divisions of the octant, and adjust the lower speculum at right
angles to the line of vision of the telescope, as before described for taking an
altitude without an horizon. Let the observer turn his back to the sun, and
look directly over the perpendicular line drawn in the under glass to the
surface of the sea before him, then drawing the index gently to him, until by
single reflection he brings the image of the sun to the horizon, the index will
then shew its altitude, proper allowance being made for his semi-diameter and
refraction on the septant, or its zenith distance on the lower figuring of the
divisions of the octant. The great and universal use of the upper glass is
to measure any sort of other distances at the pleasure of the observer, as no
fixed glass can possibly measure other than direct distances or angles; but its
uses being so manifold in measuring horizontal or other distances between
objects of unequal altitudes, in taking the transits of objects at sea, in finding
the variation of the compass, and the latitude and longitude of places, that i
would require by far too much explanation to be confined in a Specification
Here it must be carefully attended to, that if any person or persons who may
chuse to order an instrument of the aforesaid described Invention, but no

page_text: requiring to take altitudes without an horizon nor a back observation, that
in such case all that is necessary is, that these two index glasses (or one as
herein-after described) be placed on the same kind of index and plate and in
the same manner as is usually done in fixing one erect glass on Hadley's sex-
tant, and that the horizon glass have both an horizontal and vertical adjust-
ment. The index glass just alluded to is made after the same manner as the
upper glass already described; it hath its motion on its center by a tangent
screw, the shank or part near the head of which acts in a poppet made
fast into the upper part of a small arm or other contrivance made fast to
its base by screws or soldering. The point of said screw is made fast or
confined by means of another small poppet affixed into a piece made fast near
the upper part of the frame (or its motion may be given by any of the other
methods already set forth), it hath a semicircular piece and a nonices, as the
aforesaid described upper glass hath; it hath morcover on the inner part of
the back of its nonices, if its motion is given by means of a tangent screw as
already described, a small spring and tightening screw to steady it the more.
perfectly in any position, by pressing the spring by means of the tightening
screw aforesaid to the inner surface or back of its semicircular piece. This
single universal reflecting index glass, with an horizon glass silvered in two
parts, or in one part only, will perform all that both the aforesaid index
glasses will; for, when it is adjusted perpendicular to the plane of the instru-
ment, it will perform as an Hadley's sextant glass, and when it is reclined
backwards or forwards it will perform as the upper glass already described.
The future different make therefore of these instruments doth entirely depend
upon the different dispositions or choice of different persons, whilst the Inven-
tion remains the same, to wit: two index glasses instead of one as is usual,
and the upper glass having a motion on its axis or centers, to these must
belong a double-silvered horizon glass, as already described, one index glass,
but not fixed as usual, having a motion on its axis or centers, and to which,
as being but one glass, an horizon glass silvered in one part only, will be
sufficient, a circular glass tube or a pendulum, such as herein already
described, and which, by single reflection, obtains altitudes without an horizon,
the size of the instruments, and manner of numbering the divisions on their
arches, with other particulars herein already set forth these are the subjects
of the Invention. And as to the method of giving the motions already stated,
the difference of opinion of different workmen is of little avail in point of
nautical ascertainments, for if the motion is any how given by steady means,
it is perfectly sufficient.
..

page_text: The steerling or universal azimuth compass is made thus:-The height
of the pan or kettle. for a compass of eight inches diameter is about live
inches; an aperture of forty-five degrees horizontal width, and about one
inch and an half in height, is made or cut out of the side of the kettle
aforesaid, directly opposite cach other, one half or one side and the other
half on the other side of each side of the shoulders or axis of the pan,
and immediately above them two plain sights of about one and an half inch
high, six tenths of an inch wide, and having an aperture in each of about
three tenths of an inch in width, and in the center of which is fixed a hair
or silk thread. These sights are to be firmly fixed by screws or dovetail, so
that the threads or hairs aforesaid will be exactly opposite to the north and
south points of the card or needle. The apertures of the kettle or pan already
described are to be glazed with glass or ising-glass, to prevent the wind and
weather disturbing the motion of the card.
...To find the magnetic variation by this compass the method is as follows:-
Place the beginning of the vernier divisions to 0 on the septant, or to 0 on
one end or other of the octant, as the case may require. See that the
horizon glass and the index revolving glass are well adjusted together; look
directly up at the sun, or moon, or star, through the unsilvered part of the
horizon glass, by means of the tangent screw or endless screw, or other
method adopted for giving the glass its motion on its centers, being the
sun, moon, or star, down to the horizon; then ease the tightening screw, and
.bring the sun, moon, or star from the right or left, as the case may be, by
reflexion in the horizon glass to the line of coincidence of the threads scen
by direct vision through the unsilvered part of the horizon glass, and the
index will then shew the magnetic bearing or azimuth, which, when compared
to the true azimuth, will determine the variation.
In witness whereof, I have hereunto set my hand and seal, the Sevent!
day of April, in the year of our Lord One thousand seven hundre
and ninety-four.

page_text: AND BE IT REMEMBERED, that on the Ninth day of April, in the
year of our Lord 1794, the aforesaid Patrick Rooney Nugent came before
our said Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, iu form
above written. And also the Specification aforesaid was stampt according to
the tenor of the Statutes made for that purpose.
Inrolled the Ninth day of April, in the year of our Lord One thousand
seven hundred and ninety-four.

page_text: NUGENT'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PATRICK
ROONEY NUGENT, lato Cheif Surveyor of Crown Lands in the Island of
Cape Breton, in North America, but now of Gray's Inn, in the County of
Middlesex, Esquire, send greeting.
WHEREAS His most Excellent Majesty King George did, by His Letters
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Eighteenth day of March, in the thirty-fourth year of His reign, give
and grant unto me, the said Patrick Rooney Nugent, His special licence
that I, the said Patrick Rooney Nugent, during the term of years therein
mentioned; should and lawfully might use, exercise, and vend, within England,
Wales; and the Town of Berwick-upon-Tweed, my Invention of "Two-In-
STRUMENTS WHEREBY THE LATITUDE, LONGITUDE, AND MAGNETIC VARIATION AT SEA
OB ON SHORE MAY BE OBTAINED;" in which Letters Patent is contained a proviso
obliging me, the said Patrick Rooney Nugent, by an instrument in writing
under my hand and seal, to cause a particular description of the nature of
my said Invention, and in what manner the same is to be performed, to bo
inrolled in His Majesty's High Court of Chancery within one calendar month
next after the date of the said recited Letters Patent, as in and by the same,
relation being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Patrick Rooney Nugent, do hereby declare that my said Invention is used in
manner following (that is to say) :—
The instruments as deliucated on the margin hereof consist, first, of an
universal reflecting septant, sextant, oxtant, or quadrant of a glass tubb and

page_text: bubble, and of a pendulum for taking altitudes without an horizon; and,
secondly, of a steering or universal azimuth compass. The arch of the septant
contains two hundred reflected degrees, and is divided and numbered from
the centre, at which is placed 0 degrees; from thence to either extremity of
the circle it is marked or numbered regularly 5, 10, 15, 20, 25, 30, &c.,
to 100. This instrument hath an index with a vernier or nonices, which is
also divided and numbered from its middle or center, and so as to read either
way. The heads of the clamp screw and tangent screw, on the end of the
index, are both on top; the former being opposite the middle of the nonices,
and the head of the latter next the observer, in case there is an handle at the
back of the instrument as usual, otherwise they are better as they are com-
monly fixt and made. On the head of the index is a circular plate, confined
to the index by means of two scutcheons placed on or to the centre, the
lowermost of which is a square and the other a round scutcheon; or it may
be confined by any other method judged best. The head of the index, instead
of being cast or filed round, bath a small projection at the head thereof of about
half an inch, and of the width of about three fourths of an inch, which projec-
tion is a little distance before the center line or direction of the bar of the index.
Upon this projection is fixed an endless screw, by means of a clamp screwed
down to the former projection, which screw acts in a grove or sort of fine
rackwork, cut or made out of the upper edge of the circular plate already
mentioned, by a screw engine, to answer the threads of the endless screw
aforesaid, and by which endless screw the plate and the several matters thereon,
herein-after described, are horizontally adjusted as need may require. The
head of the endless screw aforesaid is placed next the observer. On the plate
before described is fixed or fastened two speculums or glasses, the lower glass
of which is made fast at right angles to the plane of the instrument, as usual
in Hadley's sextants; but it will be more form to have this glass slide into a
dovetail frame or solid case, having a grove made in it for the glass to slide
upwards into, and a small slip of brass soldered or made fast with screws to
the head of the aforesaid solid frame or case, to confine and protect the upper
edge of the glass, and any method judged best to steady it there. The upper
glass is confined in a clip or case open at the lower end, a slip of brass of
about equal size with the glass, and having four pins or points near the angles
of its ends, to prevent the silvering of the glass from being injured, and having
a case which projects therefrom upwards about the same height as the thick-
ness of the glass. This slip or piece of brass is introduced with the glass
thereon, or in front of it, up into the former case or clip, and both confined
therein by means of two small screws partly introduced through the back of

page_text: the aforesaid clip or case. This glass acts upon two centers made fast or
soldered to the sides of its frame or clip, and which centers pass through and
are confined in two pieces fastened with screws, or otherwise, to the sides of
the lower frame, and to a part of its back if found necessary. The middle
or center of these centers are to be opposite the horizontal line herein-after
mentioned to be drawn on the back of this glass. The uppermost of those
pieces (when the instrument is adjusted for taking altitudes or angles by
double reflection) hath a semicircular broad part at the upper part thereof,
(which projects backwards from the front of the glass), of at least eight
tenths of an inch radius, which must be divided into reflected degrees, so far
as to allow the observer, by assistance of the vernier belonging thereto, to read
of of about one hundred degrees. These degrees, as well as the vernier
divisions, are to be numbered from the observer when he looks at the face
or front of the glass, and to commence together when the glass is adjusted
perpendicular to the plane of the instrument. The vernier or nonices just
mentioned is fixed by means of screws to the upper part of the frame of the
glass. The motion of this glass on its centers is made by means of a tangent
screw placed opposite to the center of the glass, the shank part or head of
which screw acts in a poppet fastened into the upper part of a small arm or
other contrivance made fast to the back part of the frame, or to the case of
the frame of the lower glass, by means of screws or soldering, no part of which
arm must extend higher than the upper edge of the frame of the lower glass.
The point parts of said screw is made fast or confined by means of another
small poppet, fastened into a piece made fast to the upper part of the frame
of the glass; or the tangent screw may be inverted, or its motion may be given
by an endless screw working in a rack, cut out of the upper edge of the semi-
circular piece aforesaid, or by any other of the various methods already suffi-
ciently well known. The horizon glass hath two silvered parts, and an open
parallel space to the plane of the instrument between them; the lower part
is used with the lower index glass in all respects as Hadley's horizon and
index glasses are, but the upper is to be used with the upper index glass.
This horizon glass hath need of no horizontal adjustment, but its vertical
adjustment may be by any of the methods already sufficiently known, or such
other found most convenient. The back surfaces of the lower and upper glass
are equally divided by a perpendicular line drawn on them. The back surface
of the upper glass is also equally divided by another line drawn horizontally
thereon; the reflexion of this latter line, when the glass is vertically adjusted,
defines the lower part of the upper silvering of the horizon glass, and the
reflexion of the upper edge of the lower index glass will define the upper edgo

page_text: of the lower silvered part of the horizon glass; the space between ought to be
unsilvered, and the lower glass ought to be made so small and the upper
glass so large as to admit this space to be sufficient for all observations to
be made with this instrument. The sizes of the glasses hereby described will
be therefore nearly as follows:-Cower index glass, one and three fourths
inches in width by one inch in heighth; upper index glass, one and three
fourths inches in width by eight & one half tenths of an inch in height;
height of the lower part of the silvering of the horizon glass, six tenths of an
inch height of the upper silvered part, four tenths of an inch, and the unsilvered
space between, three tenths of an inch; as to the width of the horizon glass,
it should not exceed one inch and two tenths of an inch. The situation of
the horizon glass and telescope or plane sight are in a great manner discre-
tionary, but the most convenient and useful in a twelve-inch instrument of
this kind will be nearly as follows: The telescope four inches and seven tenths
of an inch from the center, and the horizon glass five inches and six tenths
of an inch; they must be otherwise so placed as not to interrupt the motion
of the index to the reading off the divisions to the end of the arch. The
telescope and its adjustment are the same as is usual, save that there must
be two shades placed therein, to protect the eyes from the lustre of the sun
in taking its altitude without an horizon or a back observation, and that it
should adjust so high as the upper part of the upper index glass. To take
an altitude without an horizon by this instrument there are two methods, both
of or on the same principles, namely, that of gravitation. The first is by a
perfectly circular cylindrical concave glass tube, the most conveniant size of
which for the instrument and observer will be found about seven and an half
inches radius, one fifth of an inch concavity, and one fifth of an inch thick;
this tube, to be cased with brass, excepting about threo tenths of an inch of
the surface next the center, which should be a little more in length than a
quarter of a circle, is to be so placed when used, that the lower part or sur-
face of its concavity form a perfect portion of a circle in respect to the center
of the instrument, and the height of its upper surface be about an inch and
a quarter fron the plane of the instrument; and when its inner surface or
concavity is perfectly clear, a bubble of thoroughly pure clear quicksilver or
mercury is put and used therein. When a pendulum is designed for this
instrument, either the case of the frame of the lower index glass must be
made sufficiently thick, or another plate of little more than semicircular form
is placed over the circular plate already described, which plate must be about
one fifth of an inch in thickness; this plate, or the case aforesaid, must be
to hollowed out in front as to permit the free vibrations of the pendulum in

page_text: aking altitudes from the horizon up to the zenith; the center of the instru
nent which before only extended even with the upper surface of the circular
late already mentioned, must in this case extend through the base of tho
rame of the lower index glass, or through the nearly semicircular plate just
lescribed. This additional or increased length of center supports the pen-
Bulum, which is best made in two parts, the shorter of which, of about three
inches in length, always to remain on the center, and the other part to bo
occasionally attached thereto by means of a finger screw and two steady pins.
This part last mentioned hath a semi-globular ball attached to its extreme under
end bejond the arch of the instrument, and on the flat upper face of which
slides off and on occasionally a vertical plane slide of about one and an half
inch in height and six tenths of an inch wide. On the middle of this slide is
drawn a line, which line, when the index is set to 0, and the instrument
adjusted for taking altitudes without an horizon, and the observer looks at the
horizon, he should by single reflection perceive in the under index glass level
with the surface of the sea. Withinside or near the center of the instru-
ment than the semi-ball aforesaid, and on the under surface of the pen-
dulum, is fixed four friction rollers, in two small brass pieces; these are to
play freely on the further part from the center of the arch of the instrument,
two over and two under. The whole mounting herein already described,
brass and glasses, may be placed as already set forth on any arch whatever,
whether of a sextant or quadrant, but the most conveniant lesser size will be
that of the universal reflecting octant. This instrument contains an arch of
about one hundred and ten degrees, but it is not divided or figured from the
center as the septant already described is, but from a little distance before
the limbs backwards and forwards. Thus the first space of ten or more
degrees of divisions, on the lower line next the observer, must be marked
backwards 0, 5, 10, &c.; then the said lower line is to be regularly figured
forwards from the aforesaid 0, or the observer, 5, 10, 15, 20, &c., to 100, or as
far as the arch extends; over the 100 just mentioned is marked 10, then 5,
then 0, which 0 will fall over the 90s of the former, numbering them
5, 10, 15, 20, &c., to 100, or as far as the arch runs, which 100 will fall over
the 10 backward numbering of division first mentioned; by this means the
degrees within the two 90' are made the complements of each other; then, by
5 setting the beginning of the vernier divisions to 0 on either end of the arch,
the index glasses are adjusted to the horizon glass by means of the endless
screw and plate already described. But altitudes without an horizon cannot be
conveniently taken near the horizon by means of the glass tube and bubblo

page_text: aforesaid, nor by means of the pendulum applied to this instrument, except so
far as the glass tube extends over the face of the instrument, or that the
pendulum can freely vibrate or traverse. The method of taking altitudes
without an horizon by either, is as follows:-The glass tube or pendulum
being placed as before mentioned, set the beginning of the vernier divisions
to the near 90 on the septant, or to the nearest 0 on the octant; screw back
the upper glass so as to allow sufficient space for observation between it and
the upper edge of the lower glass, then direct the line of vision of the telescope
or plane right to the center line of the lower speculum, by means of the end-
less screw already described; adjust the lower speculum at right angles to the
lino of vision; so is the instrument adjusted; look directly over the perpen-
dicular line drawn in the under glass at any object; move the index until
such time as the bubble aforesaid or the line drawn in the vertical plane
slide by single reflection in the upper edge of the lower glass is exactly hori-
zontal with the center of such object seen by direct vision over the said glass,
and the index will then shew the altitude on the septant, or its zenith dis-
tance on the lower numbering of division on the octant. It hath been before
observed, that the lower index glass on either of these instruments is used
in the same manner as Hadley's sextant; but there are other uses to which
it may be applied in these instruments; thus, to take a back observation, set
the beginning of the vernier divisions to 0 on the septant, or 90 on the lower
figuring of divisions of the octant, and adjust the lower speculum at right
angles to the line of vision of the telescope, as before described for taking an
altitude without an horizon. Let the observer turn his back to the sun, and
look directly over the perpendicular line drawn in the under glass to the
surface of the sea before him, then drawing the index gently to him, until by
single reflection he brings the image of the sun to the horizon, the index will
then shew its altitude, proper allowance being made for his semi-diameter and
.refraction on the septant, or its zenith distance on the lower figuring of the
divisions of the octant. The great and universal use of the upper glass is
to measure any sort of other distances at the pleasure of the observer, as no
fixed glass can possibly measure other than direct distances or angles; but its
uses being so manifold in measuring horizontal or other distances between
objects of unequal altitudes, in taking the transits of objects at sea, in finding
the variation of the compass, and the latitude and longitude of places, that i
would require by far too much explanation to be confined in a Specification.
Here it must be carefully attended to, that if any person or persons who may
chuse to order an instrument of the aforesaid described Invention, but no

page_text: requiring to take altitudes without an horizon nor a back observation, that
in such case all that is necessary is, that these two index glasses (or one as
herein-after described) be placed on the same kind of index and plate and in
the same manner as is usually done in fixing one erect glass on Hadley's sex-
tant, and that the horizon glass have both an horizontal and vertical adjust-
ment. The index glass just alluded to is made after the same manner as the
upper glass already described; it hath its motion on its center by a tangent
screw, the shank or part near the head of which acts in a poppet made
fast into the upper part of a small arm or other contrivance made fast to
its base by screws or soldering. The point of said screw is made fast or
confined by means of another small poppet affixed into a piece made fast near
the upper part of the frame. (or its motion may be given by any of the other
methods already set forth), it hath a semicircular piece and a nonices, as tho
aforesaid described upper glass hath; it hath morcover on the inner part of
the back of its nonices, if its motion is given by means of a tangent screw as
already described, a small spring and tightening screw to steady it the more.
perfectly in any position, by pressing the spring by means of the tightening
screw aforesaid to the inner surface or back of its semicircular piece. This
single universal reflecting index glass, with an horizon glass silvered in two
parts, or in one part only, will perform all that both the aforesaid index
glasses will; for, when it is adjusted perpendicular to the plane of the instru-
ment, it will perform as an Hadley's sextant glass, and when it is reclined
backwards or forwards it will perform as the upper glass already described.
The future different make therefore of these instruments doth entirely depend
upon the different dispositions or choice of different persons, whilst the Inven-
tion remains the same, to wit: two index glasses instead of one as is usual,
and the upper glass having a motion on its axis or centers, to these must
belong a double-silvered horizon glass, as already described, one index glass,
but not fixed as usual, having a motion on its axis or centers, and to which,
as being but one glass, an horizon glass silvered in one part only, will be
sufficient, a circular glass tube or a pendulum, such as herein already
described, and which, by single reflection, obtains altitudes without an horizon,
the size of the instruments, and manner of numbering the divisions on their
arches, with other particulars herein already set forth: these are the subjects
of the Invention. And as to the method of giving the motions already stated,
the difference of opinion of different workmen is of little avail in point of
nautical ascertainments, for if the motion is any how given by steady means,
it is perfectly sufficient.

page_text: The steerling or universal azimuth compass is made thus:-The height
of the pan or kettle, for a compass of eight inches diameter is about five
inches; an aperture of forty-five degrees horizontal width, and about one
inch and an balf in height, is made or cut out of the side of the kettle
aforesaid, directly opposite cach other, one half or one side and the other
half on the other side of each side of the shoulders or axis of the pan,
and immediately above them two plain sights of about one and an half inch
high, six tenths of an inch wide, and having an aperture in each of about
three tenths of an inch in width, and in the center of which is fixed a hair
or silk thread. These sights are to be firmly fixed by screws or dovetail, so
that the threads or hairs aforesaid will be exactly opposite to the north and
south points of the card or needle. The apertures of the kettle or pan already
described are to be glazed with glass or ising-glass, to prevent the wind and
weather disturbing the motion of the card.
To find the magnetic variation by this compass the method is as follows:-
Place the beginning of the vernier divisions to 0 on the septant, or to 0 on
one end or other of the octant, as the case may require. See that the
horizon glass and the index revolving glass are well adjusted together; look
directly up at the sun, or moon, or star, through the unsilvered part of the
horizon glass, by means of the tangent screw or endless screw, or other
-method adopted for giving the glass its motion on its centers, being the
sun, moon, or star, down to the horizon; then ease the tightening screw, and
..bring the sun, moon, or star from the right or left, as the case may be, by
reflexion in the horizon glass to the line of coincidence of the threads seen
by direct vision through the unsilvered part of the horizon glass, and the
index will then shew the magnetic bearing or azimuth, which, when compared
to the true azimuth, will determine the variation.
In witness whereof, I have hereunto set my hand and seal, the Sevent
day of April, in the year of our Lord One thousand seven hundre
and ninety-four.

page_text: AND BE IT REMEMBERED, that on the Ninth day of April, in the
year of our Lord 1794, the aforesaid Patrick Rooney Nugent came before
our said Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stampt according to
the tenor of the Statutes made for that purpose.
Inrolled the Ninth day of April, in the year of our Lord One thousand
seven hundred and ninety-four.

page_text: NUGENT'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PATRICK
ROONEY NUGENT, late Cheif Surveyor of Crown Lands in the Island of
Cape Breton, in North America, but now of Gray's Inn, in the County of
Middlesex, Esquire, send greeting.
.. WHEREAS His most Excellent Majesty King George did, by His Letters
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Eighteenth day of March, in the thirty-fourth year of His reign, give
and grant unto me, the said Patrick Rooney Nugent, His special licence
that I, the said Patrick Rooney Nugent, during the term of years therein
mentioned; should and lawfully might use, exercise, and vend, within England,
Wales; and the Town of Berwick-upon-Tweed, my Invention of "Two IN-
STRUMENTS WHEREBY THE LATITUDE, LONGITUDE, AND MAGNETIC VARIATION AT SEA
OR ON SHORE MAY BE OBTAINED;" in which Letters Patent is contained a proviso
obliging me, the said Patrick Rooney Nugent, by an instrument in writing
under my hand and seal, to cause a particular description of the nature of
my said Invention, and in what manner the same is to be performed, to be
inrolled in His Majesty's High Court of Chancery within one calendar month
next after the date of the said recited Letters Patent, as in and by the same,
relation being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Patrick Rooney Nugent, do hereby declare that my said Invention is used in
manner following (that is to say) :-
The instruments as delineated on the margin hereof consist, first, of an
universal reflecting septant, sextant, oxtant, or quadrant of a glass tubb and

page_text: bubble, and of a pendulum for taking altitudes without an horizon; and,
secondly, of a steering or universal azimuth compass. The arch of the septant
contains two hundred reflected degrees, and is divided and numbered from
the centre, at which is placed 0 degrees; from thence to either extremity of
the circle it is marked or numbered regularly 5, 10, 15, 20, 25, 30, &c.,
to 100. This instrument hath an index with a vernier or nonices, which is
also divided and numbered from its middle or center, and so as to read either
way. The heads of the clamp screw and tangent screw, on the end of the
index, are both on top; the former being opposite the middle of the nonices,
and the head of the latter next the observer, in case there is an handle at the
back of the instrument as usual, otherwise they are better as they are com-
monly fixt and made. On the head of the index is a circular plate, confined
to the index by means of two scutcheons placed on or to the centre, the
lowermost of which is a square and the other a round scutcheon; or it may
be confined by any other method judged best. The head of the index, instead
of being cast or filed round, hath a small projection at the head thereof of about
half an inch, and of the width of about three fourths of an inch, which projec-
tion is a little distance before the center line or direction of the bar of the index.
Upon this projection is fixed an endless screw, by means of a clamp screwed
down to the former projection, which screw acts in a grove or sort of fine
rackwork, cut or made out of the upper edge of the circular plate already
mentioned, by a screw engine, to answer the threads of the endless screw
aforesaid, and by which endless screw the plate and the several matters thereon,
herein-after described, are horizontally adjusted as need may require. The
head of the endless screw aforesaid is placed next the observer. On the plate
before described is fixed or fastened two speculums or glasses, the lower glass
of which is made fast at right angles to the plane of the instrument, as usual
in Hadley's sextants; but it will be more form to have this glass slide into a
dovetail frame or solid case, having a grove made in it for the glass to slide
upwards into, and a small slip of brass soldered or made fast with screws to
the head of the aforesaid solid frame or case, to confine and protect the upper
odge of the glass, and any method judged best to steady it there. The upper
glass is confined in a clip or case open at the lower end, a slip of brass of
about equal size with the glass, and having four pins or points near the angles
of its ends, to prevent the silvering of the glass from being injured, and having
a case which projects therefrom upwards about the same height as the thick-
ness of the glass. This slip or piece of brass is introduced with the glass
thereon, or in front of it, up into the former case or clip, and both confined
therein by means of two small screws partly introduced through the back of

page_text: the aforesaid clip or case. This glass acts upon two centers made fast or
soldered to the sides of its frame or clip, and which centers pass through and
are confined in two pieces fastened with screws, or otherwise, to the sides of
the lower frame, and to a part of its back if found necessary. The middle
or center of these centers are to be opposite the horizontal line herein-after
mentioned to be drawn on the back of this glass. The uppermost of those
pieces (when the instrument is adjusted for taking altitudes or angles by
double reflection) hath a semicircular broad part at the upper part thereof,
(which projects backwards from the front of the glass), of at least eight
tenths of an inch radius, which must be divided into reflected degrees, so far
as to allow the observer, by assistance of the vernier belonging thereto, to read
of of about one hundred degrees. These degrees, as well as the vernier
divisions, are to be numbered from the observer when he looks at the face
or front of the glass, and to commence together when the glass is adjusted
perpendicular to the plane of the instrument. The vernier or nonices just
mentioned is fixed by means of screws to the upper part of the frame of the
glass. The motion of this glass on its centers is made by means of a tangent
screw placed opposite to the center of the glass, the shank part or head of
which screw acts in a poppet fastened into the upper part of a small arm or
other contrivance made fast to the back part of the frame, or to the case of
the frame of the lower glass, by means of screws or soldering, no part of which
arm must extend higher than the upper edge of the frame of the lower glass.
The point parts of said screw is made fast or confined by means of another
small poppet, fastened into a piece made fast to the upper part of the frame
of the glass; or the tangent screw may be inverted, or its motion may be given
by an endless screw working in a rack, cut out of the upper edge of the semi-
circular piece aforesaid, or by any other of the various methods already suffi-
ciently well known. The horizon glass hath two silvered parts, and an open
parallel space to the plane of the instrument between them; the lower part
is used with the lower index glass in all respects as Hadley's horizon and
index glasses are, but the upper is to be used with the upper index glass.
This horizon glass hath need of no horizontal adjustment, but its vertical
adjustment may be by any of the methods already sufficiently known, or such
other found most convenient. The back surfaces of the lower and upper glass
are equally divided by a perpendicular line drawn on them. The back surface
of the upper glass is also equally divided by another line drawn horizontally
thereon; the reflexion of this latter line, when the glass is vertically adjusted,
defines the lower part of the upper silvering of the horizon glass, and the
reflexion of the upper edge of the lower index glass will define the upper edgo

page_text: of the lower silvered part of the horizon glass; the space between ought to be
unsilvered, and the lower glass ought to be made so small and the upper
glass so large as to admit this space to be sufficient for all observations to
be made with this instrument. The sizes of the glasses hereby described will
be therefore nearly as follows:-Cower index glass, one and three fourths
inches in width by one inch in heighth; upper index glass, ono and three
fourths inches in width by eight & one half tenths of an inch in height;
height of the lower part of the silvering of the horizon glass, six tenths of an
inch: height of the upper silvered part, four tenths of an inch, and the unsilvered
space between, three tenths of an inch; as to the width of the horizon glass,
it should not exceed one inch and two tenths of an inch. The situation of
the horizon glass and telescope or plane sight are in a great manner discre-
tionary, but the most convenient and useful in a twelve-inch instrument of
this kind will be nearly as follows: The telescope four inches and seven tenths
of an inch from the center, and the horizon glass five inches and six tenths
of an inch; they must be otherwise so placed as not to interrupt the motion
of the index to the reading off the divisions to the end of the arch. The
telescope and its adjustment are the same as is usual, save that there must
be two shades placed therein, to protect the eyes from the lustre of the sun
in taking its altitude without an horizon or a back observation, and that it
should adjust so high as the upper part of the upper index glass. To take
an altitude without an horizon by this instrument there are two methods, both
of or on the same principles, namely, that of gravitation. The first is by a
perfectly circular cylindrical concave glass tube, the most conveniant size of
which for the instrument and observer will be found about seven and an half
inches radius, one fifth of an inch concavity, and one fifth of an inch thick;
this tube, to be cased with brass, excepting about threo tenths of an inch of
the surface next the center, which should be a little more in length than a
quarter of a circle, is to be so placed when used, that the lower part or sur-
face of its concavity form a perfect portion of a circle in respect to the center
of the instrument, and the height of its upper surface be about an inch and
a quarter fron the plane of the instrument; and when its inner surface or
concavity is perfectly clear, a bubble of thoroughly pure clear quicksilver or
mercury is put and used therein. When a pendulum is designed for this
instrument, either the case of the frame of the lower index glass must be
made sufficiently thick, or another plate of little more than semicircular form
is placed over the circular plate already described, which plate must be about
one fifth of an inch in thickness; this plate, or the case aforesaid, must be
to hollowed out in front as to permit the free vibrations of the pendulum in
.

page_text: aking altitudes from the horizon up to the zenith; the center of the instru-
nent which before only extended even with the upper surface of the circular
late already mentioned, must in this case extend through the base of the
rame of the lower index glass, or through the nearly semicircular plate just
described. This additional or increased length of center supports the pen-
Julum, which is best made in two parts, the shorter of which, of about three
inches in length, always to remain on the center, and the other part to bo
occasionally attached thereto by means of a finger screw and two steady pins.
This part last mentioned hath a semi-globular ball attached to its extreme under
end bejond the arch of the iustrument, and on the flat upper face of which
slides off and on occasionally a vertical plane slide of about one and an half
inch in height and six tenths of an inch wide. On the middle of this slide is
drawn a line, which line, when the index is set to 0, and the instrument
adjusted for taking altitudes without an horizon, and the observer looks at the
horizon, he should by single reflection perceive in the under index glass level
with the surface of the sca. Withinside or near the center of the instru-
ment than the semi-ball aforesaid, and on the under surface of the pen-
dulum, is fixed four friction rollers, in two small brass pieces; these are to
play freely on the further part from the center of the arch of the instrument,
two over and two under. The whole mounting herein already described,
brass and glasses, may be placed as already set forth on any arch whatever,
whether of a sextant or quadrant, but the most conveniant lesser size will be
that of the universal reflecting octant. This instrument contains an arch of
about one hundred and ten degrees, but it is not divided or figured from the
center as the septant already described is, but from a littlo distance before
the limbs backwards and forwards. Thus the first space of ten or more
degrees of divisions, on the lower line next the observer, must be marked
backwards 0, 5, 10, &c.; then the said lower line is to be regularly figured
forwards from the aforesaid 0, or the observer, 5, 10, 15, 20, &c., to 100, or as
far as the arch extends; over the 100 just mentioned is marked 10, then 5,
then 0, which 0 will fall over the 90' of the former, numbering them
5, 10, 15, 20, &c., to 100, or as far as the arch runs, which 100 will fall over
the 10 backward numbering of division first mentioned; by this means the
degrees within the two 90s are made the complements of each other; then, by
5 setting the beginning of the vernier divisions to 0 on either end of the arch,
the index glasses are adjusted to the horizon glass by means of the endless
screw and plate already described. But altitudes without an horizon cannot be
conveniently taken near the horizon by means of the glass tube and bubble

page_text: aforesaid, nor by micans of the pendulum applied to this instrument, except so
far as the glass tube extends over the face of the instrument, or that the
pendulum can freely vibrate or traverse. The method of taking altitudes
without an horizon by either, is as follows:-The glass tube or pendulum
being placed as before mentioned, set the beginning of the vernier divisions
to the near 90 on the septant, or to the nearest 0 on the octant; screw back
the upper glass so as to allow sufficient space for observation between it and
the upper edge of the lower glass, then direct the line of vision of the telescope
or plane right to the center line of the lower speculum, by means of the end-
less screw already described; adjust the lower speculum at right angles to the
lino of vision; so is the instrument adjusted; look directly over the perpen-
dicular line drawn in the under glass at any object; move the index until
such time as the bubble aforesaid or the line drawn in the vertical plane
slide by single reflection in the upper edge of the lower glass is exactly hori-
zontal with the center of such object seen by direct vision over the said glass,
and the index will then shew the altitude on the septant, or its zenith dis-
tance on the lower numbering of division on the octant. It hath been before
observed, that the lower index glass on either of these instruments is used
in the same manner as Hadley's sextant; but there are other uses to which
be applied in these instruments; thus, to take a back observation, set
the beginning of the vernier divisions to 0 on the septant, or 90 on the lower
figuring of divisions of the octant, and adjust the lower speculum at right
angles to the line of vision of the telescope, as before described for taking an
altitude without an horizon. Let the observer turn his back to the sun, and
look directly over the perpendicular line drawn in the under glass to the
surface of the sea before him, then drawing the index gently to him, until by
single reflection he brings the image of the sun to the horizon, the index will
then shew its altitude, proper allowance being made for his semi-diameter and
refraction on the septant, or its zenith distance on the lower figuring of the
divisions of the octant. The great and universal use of the upper glass is,
to measure any sort of other distances at the pleasure of the observer, as no
fixed glass can possibly measure other than direct distances or angles; but its
uses being so manifold in measuring horizontal or other distances between
objects of unequal altitudes, in taking the transits of objects at sea, in finding
the variation of the compass, and the latitude and longitude of places, that i
would require by far too much explanation to be confined in a Specification
Here it must be carefully attended to, that if any person or persons who may
chuse to order an instrument of the aforesaid described Invention, but no
it
may

page_text: requiring to take altitudes without an horizon nor a back observation, that
in such case all that is necessary is, that these two index glasses (or one as
herein-after described) be placed on the same kind of index and plate and in
the same manner as is usually done in fixing one crect glass on Hadley's sex-
tant, and that the horizon glass have both an horizontal and vertical adjust-
ment. The index glass just alluded to is made after the same manner as the
upper glass already described; it hath its motion on its center by a tangent
scrow, the shank or part near the head of which acts in a poppet made
fast into the upper part of a small arm or other contrivance made fast to
its base by screws or soldering. The point of said screw is made fast or
confined by means of another small poppet affixed into a piece made fast near
the upper part of the frame (or its motion may be given by any of the other
methods already set forth), it hath a semicircular piece and a nonices, as the
aforesaid described upper glass hath; it hath moreover on the inner part of
the back of its nonices, if its motion is given by means of a tangent screw as
already described, a small spring and tightening screw to steady it the more.
perfectly in any position, by pressing the spring by means of the tightening
screw aforesaid to the inner surface or back of its semicircular piece. This
single universal reflecting index glass, with an horizon glass silvered in two
parts, or in one part only, will perform all that both the aforesaid index
glasses will; for, when it is adjusted perpendicular to the plane of the instru-
ment, it will perform as an Hadley's sextant glass, and when it is reclined
backwards or forwards it will perform as the upper glass already described.
The future different make therefore of these instruments doth entirely depend
upon the different dispositions or choice of different persons, whilst the Inven-
tion remains the same, to wit: two index glasses instead of one as is usual,
and the upper glass having a motion on its axis or centers, to these must
belong a double-silvered horizon glass, as already described, one index glass,
but not fixed as usual, having a motion on its axis or centers, and to which,
as being but one glass, an horizon glass silvered in one part only, will be
sufficient, a circular glass tube cr a pendulum, such as herein already
described, and which, by single reflection, obtains altitudes without an horizon,
the size of the instruments, and manner of numbering the divisions on their
arches, with other particulars herein already set forth: these are the subjects
of the Invention. And as to the method of giving the motions already stated,
the difference of opinion of different workmen is of little avail in point of
nautical ascertainments, for if the motion is any how given by steady means,
it is perfectly sufficient.

page_text: The steerling or universal azimuth compass is made thus:-The height
of the pan or kettle for a compass of eight inches diameter is about five
inches; an aperture of forty-five degrees horizontal width, and about one
inch and an half in height, is made or cut out of the side of the kettle
aforesaid, directly opposite each other, one half or one side and the other 5
half on the other side of each side of the shoulders or axis of the pan,
and immediately above them two plain sights of about one and an half inch
high, six tenths of an inch wide, and having an aperture in each of about
three tenths of an inch in width, and in the center of which is fixed a hair
or silk thread. These sights are to be firmly fixed by screws or dovetail, so
that the threads or hairs aforesaid will be exactly opposite to the north and
south points of the card or needle. The apertures of the kettle or pan already
described are to be glazed with glass or ising-glass, to prevent the wind and
weather disturbing the motion of the card.
To find the magnetic variation by this compass the method is as follows:-
Place the beginning of the vernier divisions to 0 on the septant, or to 0 on
prio end or other of the octant, as the case may require.
See that the
horizon glass and the index revolving glass are well adjusted together; look
directly up at the sun, or moon, or star, through the unsilvered part of the
horizon glass, by means of the tangent screw or endless screw, or other
method adopted for giving the glass its motion on its centers, being the
sun, moon, or star, down to the horizon; then ease the tightening screw, and
.bring the sun, moon, or star from the right or left, as the case may be, by
reflexion in the horizon glass to the line of coincidence of the threads scen
by direct vision through the unsilvered part of the horizon glass, and the
index will then shew the magnetic bearing or azimuth, which, when compared
to the true azimuth, will determine the variation.
In witness whereof, I have hereunto set iny hand and seal, the Seventh
day of April, in the year of our Lord One thousand seven bundred

page_text: AND BE IT REMEMBERED, that on the Ninth day of April, in the
year of our Lord 1794, the aforesaid Patrick Rooney Nugent came before
our said Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stampt according to
the tenor of the Statutes made for that purpose.
Inrolled the Ninth day of April, in the year of our Lord One thousand
seven hundred and ninety-four.

page_text: I NUGENT'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PATRICK
ROONEY NUGENT, lato Cheif Surveyor of Crown Lands in the Island of
Cape Breton, in North America, but now of Gray's Inn, in the County of
Middlesex, Esquire, send greeting.
WHEREAS His most Excellent Majesty King George did, by His Lettors
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Eighteenth day of March, in the thirty-fourth year of His reign, give
and grant unto me, the said Patrick Rooney Nugent, His special licence
that I, the said Patrick Rooney Nugent, during the term of years therein
mentioned; should and lawfully might use, exercise, and vend, within England,
Wales; and the Town of Berwick-upon-Tweed, my Invention of "Two. IN-
STRUMENTS WHEREBY THE LATITUDE, LONGITUDE, AND MAGNETIC VARIATION AT SEA
OR ON SHORE MAY BE OBTAINED;" in which Letters Patent is contained a proviso
obliging me, the said Patrick Rooney Nugent, by an instrument in writing
under my hand and seal, to cause a particular description of the nature of
my said Invention, and in what manner the same is to be performed, to bo
inrolled in His Majesty's High Court of Chancery within one calendar month
next after the date of the said recited Letters Patent, as in and by the same,
relation being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Patrick Rooney Nugent, do hereby declare that my said Invention is used in
manner following (that is to say) :—
The instruments as delineated on the margin hereof consist, first, of an
universal reflecting septant, sextant, oxtant, or quadrant of a glass tubb and

page_text: bubble, and of a pendulum for taking altitudes without an horizon; and,
secondly, of a steering or universal azimuth compass. The arch of the septant
contains two hundred reflected degrees, and is divided and numbered from
the centre, at which is placed 0 degrees; from thence to either extremity of
the circle it is marked or nunibered regularly 5, 10, 15, 20, 25, 30, &c.,
to 100. This instrument hath an index with a vernier or nonices, which is
also divided and numbered from its middle or center, and so as to read either
way. The heads of the clamp screw and tangent screw, on the end of the
index, are both on top; the former being opposite the middle of the nonices,
and the head of the latter next the observer, in case there is an handle at the
back of the instruinent as usual, otherwise they are better as they are com-
monly fixt and made. On the head of the index is a circular plate, confined
to the index by means of two 'scutcheons placed on or to the centre, the
lowermost of which is a square and the other a round scutchicon; or it may
be confined by any other method judged best. The head of the index, instead
of being cast or filed round, hath a small projection at the head thereof of about
half an inch, and of the width of about three fourths of an inch, which projec-
tion is a little distance before the center line or direction of the bar of the index.
Upon this projection is fixed an endless screw, by means of a clamp screwed
down to the former projection, which screw acts in a grove or sort of fine
rackwork, cut or made out of the upper edge of the circular plate already
mentioned, by a screw engine, to answer the threads of the endless screw
aforesaid, and by which endless screw the plate and the several matters thereon,
herein-after described, are horizontally adjusted as need may require. The
head of the endless screw aforesaid is placed next the observer. On the plate
before described is fixed or fastened two speculums or glasses, the lower glass
of which is made fast at right angles to the plane of the instrument, as usual
in Hadley's sextants; but it will be more form to have this glass slide into a
dovetail frame or solid case, having a grove made in it for the glass to slide
upwards into, and a small slip of brass soldered or made fast with screws to
the head of the aforesaid solid frame or case, to confine and protect the upper
odge of the glass, and any method judged best to steady it there. The upper
glass is confined in a clip or case open at the lower end, a slip of brass of
about equal size with the glass, and having four pins or points near the angles
of its ends, to prevent the silvering of the glass from being injured, and having
a case which projects therefrom upwards about the same height as the thick-
ness of the glass. This slip or piece of brass is introduced with the glass
thereon, or in front of it, up into the former case or clip, and both confined
therein by means of two small screws partly introduced through the back of

page_text: the aforesaid clip or case. This glass acts upon two centers made fast or
soldered to the sides of its frame or clip, and which centers pass through and
are confined in two pieces fastened with screws, or otherwise, to the sides of
the lower frame, and to a part of its back if found necessary. The middle
or center of these centers are to be opposite the horizontal line herein-after
mentioned to be drawn on the back of this glass. The uppermost of those
pieces (when tho instrument is adjusted for taking altitudes or angles by
double reflection) hath a semicircular broad part at the upper part thereof,
(which projects backwards from the front of the glass), of at least eight
tenths of an inch radius, which must be divided into reflected degrees, so far
as to allow the observer, by assistance of the vernier belonging thereto, to read
of of about one hundred degrees. These degrees, as well as the vernier
divisions, are to be numbered from the observer when he looks at the face
or front of the glass, and to commence together when the glass is adjusted
perpendicular to the plane of the instrument. The vernier or nonices just
mentioned is fixed by means of screws to the upper part of the frame of the
glass. The motion of this glass on its centers is made by means of a tangent
screw placed opposite to the center of the glass, the shank part or head of
which screw acts in a poppet fastened into the upper part of a small arm or
other contrivance made fast to the back part of the frame, or to the case of
the frame of the lower glass, by means of screws or soldering, no part of which
arm must extend higher than the upper edge of the frame of the lower glass.
The point parts of said screw is made fast or confined by means of another
small poppet, fastened into a piece made fast to the upper part of the frame
of the glass; or the tangent screw may be inverted, or its motion may be given
by an endless screw working in a rack, cut out of the upper edge of the semi-
circular piece aforesaid, or by any other of the various methods already suffi-
ciently well known. The horizon glass hath two silvered parts, and an open
parallel space to the plane of the instrument between them; the lower part
is used with the lower index glass in all respects as Hadley's horizon and
index glasses are, but the upper is to be used with the upper index glass.
This horizon glass hath need of no horizontal adjustment, but its vertical
adjustment may be by any of the methods already sufficiently known, or such
other found most convenient. The back surfaces of the lower and upper glass
are equally divided by a perpendicular line drawn on them. The back surface
of the upper glass is also equally divided by another line drawn horizontally
thereon; the reflexion of this latter line, when the glass is vertically adjusted,
defines the lower part of the upper silvering of the horizon glass, and the
reflexion of the upper edge of the lower index glass will define the upper edgo

page_text: of the lower silvered part of the horizon glass; the space between ought to be
unsilvered, and the lower glass ought to be made so small and the upper
glass so large as to admit this space to be sufficient for all observations to
be made with this instrument. The sizes of the glasses hereby described will
be therefore nearly as follows:-Cower index glass, one and three fourths
inches in width by one inch in heighth; upper index glass, one and three
fourths inches in width by eight & one half tenths of an inch in height;
height of the lower part of the silvering of the horizon glass, six tenths of an
inch height of the upper silvered part, four tenths of an inch, and the unsilvered
space between, three tenths of an inch; as to the width of the horizon glass,
it should not exceed one inch and two tenths of an inch. The situation of
the horizon glass and telescope or plane sight are in a great manner discre-
tionary, but the most convenient and useful in a twelve-inch instrument of
this kind will be nearly as follows: The telescope four inches and seven tenths
of an inch from the center, and the horizon glass five inches and six tenths
of an inch; they must be otherwise so placed as not to interrupt the motion
of the index to the reading off the divisions to the end of the arch. The
telescope and its adjustment are the same as is usual, save that there must
bo two shades placed therein, to protect the eyes from the lustre of the sun
in taking its altitude without an horizon or a back observation, and that it
should adjust so high as the upper part of the upper index glass. To take
an altitude without an horizon by this instrument there are two methods, both
of or on the same principles, namely, that of gravitation. The first is by a
perfectly circular cylindrical concave glass tube, the most conveniant size of
which for the instrument and observer will be found about seven and an half
inches radius, one fifth of an inch concavity, and one fifth of an inch thick;
this tube, to be eased with brass, excepting about three tenths of an inch of
the surface next the center, which should be a little more in length than a
quarter of a circle, is to be so placed when used, that the lower part or sur-
face of its concavity form a perfect portion of a circle in respect to the center
of the instrument, and the height of its upper surface be about an inch and
a quarter fron the plane of the instrument; and when its inner surface or
concavity is perfectly clear, a bubble of thoroughly puro clear quicksilver or
mercury is put and used therein. When a pendulum is designed for this
instrument, either the case of the frame of the lower index glass must be
made sufficiently thick, or another plate of little more than semicircular form
is placed over the circular plate already described, which plate must be about
one fifth of an inch in thickness; this plate, or the case aforesaid, must bo
to hollowed out in front as to permit the free vibrations of the pendulum in

page_text: aking altitudes from the horizon up to the zenith; the center of the instru
ment which before only extended even with the upper surface of the circular
late already mentioned, must in this case extend through the base of the
rame of the lower index glass, or through the nearly semicircular plate just
described. This additional or increased length of center supports the pen-
dulum, which is best made in two parts, the shorter of which, of about three
inches in length, always to remain on the center, and the other part to bo
occasionally attached thereto by means of a finger screw and two steady pins.
This part last mentioned hath a semi-globular ball attached to its extreme under
end bejond the arch of the instrument, and on the flat upper face of which
slides off and on occasionally a vertical plane slide of about one and an half
inch in height and six tenths of an inch wide. On the middle of this slide is
drawn a line, which line, when the index is set to 0, and the instrument
adjusted for taking altitudes without an horizon, and the observer looks at the
horizon, he should by single reflection perceive in the under index glass level
with the surface of the sea. Withinside or near the center of the instru-
ment than the semi-ball aforesaid, and on the under surface of the pen-
dulum, is fixed four friction rollers, in two small brass pieces; these are to
play freely on the further part from the center of the arch of the instrument,
two over and two under. The whole mounting herein already described,
brass and glasses, may be placed as already set forth on any arch whatever,
whether of a sextant or quadrant, but the most conveniant lesser size will be
that of the universal reflecting octant. This instrument contains an arch of
about one hundred and ten degrees, but it is not divided or figured from the
center as the septant already described is, but from a little distance before
the limbs backwards and forwards. Thus the first space of ten or more
degrees of divisions, on the lower line next the observer, must be marked
backwards 0, 5, 10, &c.; then the said lower line is to be regularly figured
forwards from the aforesaid 0, or the observer, 5, 10, 15, 20, &c., to 100, or as
far as the arch extends; over the 100 just mentioned is marked 10, then 5,
then 0, which 0 will fall over the 90% of the former, numbering them
5, 10, 15, 20, &c., to 100, or as far as the arch runs, which 100 will fall over
the 10 backward numbering of division first mentioned by this means the
degrees within the two 90' are made the complements of each other; then, by
5 setting the beginning of the vernier divisions to 0 on either end of the arch,
the index glasses are adjusted to the horizon glass by means of the endless
screw and plate already described. But altitudes without an horizon cannot be
conveniently taken near the horizon by means of the glass tube and bubblo

page_text: aforesaid, nor by means of the pendulum applied to this instrument, except so
far as the glass tube extends over the face of the instrument, or that the
pendulum can freely vibrate or traverse. The method of taking altitudes
without an borizon by either, is as follows:-The glass tube or pendulum
being placed as before mentioned, set the beginning of the vernier divisions
to the near 90 on the septant, or to the nearest 0 on the octant; screw back
the upper glass so as to allow sufficient space for observation between it and
the upper edge of the lower glass, then direct the line of vision of the telescope
or plane right to the center line of the lower speculum, by means of the end-
less screw already described; adjust the lower speculum at right angles to the
line of vision; so is the instrument adjusted; look directly over the perpen-
dicular line drawn in the under glass at any object; move the index until
such time as the bubble aforesaid or the line drawn in the vertical plane
slide by single reflection in the upper edge of the lower glass is exactly hori-
zontal with the center of such object seen by direct vision over the said glass,
and the index will then shew the altitude on the septant, or its zenith dis-
tance on the lower numbering of division on the octant. It hath been before
observed, that the lower index glass on either of these instruments is used
in the same manner as Hadley's sextant; but there are other uses to which
it may be applied in these instruments; thus, to take a back observation, set
the beginning of the vernier divisions to 0 on the septant, or 90 on the lower
figuring of divisions of the octant, and adjust the lower speculum at right
angles to the line of vision of the telescope, as before described for taking an
altitude without an horizon. Let the observer turn his back to the sun, and
look directly over the perpendicular line drawn in the under glass to the
surface of the sea before him, then drawing the index gently to him, until by
single reflection he brings the image of the sun to the horizon, the index will
then shew its altitude, proper allowance being made for his semi-diameter and
refraction on the septant, or its zenith distance on the lower figuring of the
divisions of the octant. The great and universal use of the upper glass is
to measure any sort of other distances at the pleasure of the observer, as no
fixed glass can possibly measure other than direct distances or angles; but its
uses being so manifold in measuring horizontal or other distances between
objects of unequal altitudes, in taking the transits of objects at sea, in finding
the variation of the compass, and the latitude and longitude of places, that i
would require by far too much explanation to be confined in a Specification
Here it must be carefully attended to, that if any person or persons who may
chuse to order an instrument of the aforesaid described Invention, but no

page_text: requiring to take altitudes without an horizon nor a back observation, that
in such case all that is necessary is, that these two index glasses (or one as
herein-after described) be placed on the same kind of index and plate and in
the same manner as is usually done in fixing one erect glass on Hadiey's sex-
tant, and that the horizon glass have both an horizontal and vertical adjust-
ment. The index glass just alluded to is made after the same manner as the
upper glass already described; it hath its motion on its center by a tangent
screw, the shank or part near the head of which acts in a poppet made
fast into the upper part of a small arm or other contrivance made fast to
its base by screws or soldering. The point of said screw is made fast or
confined by means of another small poppet affixed into a piece made fast near
the upper part of the frame (or its motion may be given by any of the other
methods already set forth), it hath a semicircular piece and a nonices, as the
aforesaid described upper glass hath; it hath moreover on the inner part of
the back of its nonices, if its motion is given by means of a tangent screw as
already described, a small spring and tightening screw to steady it the more.
perfectly in any position, by pressing the spring by means of the tightening
screw aforesaid to the inner surface or back of its semicircular piece. This
single universal reflecting index glass, with an horizon glass silvered in two
parts, or in one part only, will perform all that both the aforesaid index
glasses will; for, when it is adjusted perpendicular to the plane of the instru-
ment, it will perform as an Hadley's sextant glass, and when it is reclined
backwards or forwards it will perform as the upper glass already described.
The future different make therefore of these instruments doth entirely depend
upon the different dispositions or choice of different persons, whilst the Inven-
tion remains the same, to wit: two index glasses instead of one as is usual,
and the upper glass having a motion on its axis or centers, to these must "
belong a double-silvered horizon glass, as already described, one index glass,
but not fixed as usual, having a motion on its axis or centers, and to which,
as being but one glass, an horizon glass silvered in one part only, will be
sufficient, a circular glass tube or a pendulum, such as herein already
described, and which, by single reflection, obtains altitudes without an horizon,
the size of the instruments, and manner of numbering the divisions on their
arches, with other particulars herein already set forth: these are the subjects
of the Invention. And as to the method of giving the motions already stated,
the difference of opinion of different workmen is of little avail in point of
nautical ascertainments, for if the motion is any how given by steady means,
it is perfectly sufficient.

page_text: The steerling or universal azimuth compass is made thus:-The height
of the pan or kettle, for a compass of eight inches diameter is about live
inches; an aperture of forty-five degrees horizontal width, and about one
inch and an half in height, is made or cut out of the side of the kettle
aforesaid, directly opposite cach other, one half or one side and the other
half on the other side of each side of the shoulders or axis of the pan,
and immediately above them two plain sights of about one and an half inch
high, six tenths of an inch wide, and having an aperture in cach of about
three tenths of an inch in width, and in the center of which is fixed a hair
or silk thread. These sights are to be firmly fixed by screws or dovetail, so
that the threads or hairs aforesaid will be exactly opposite to the north and
south points of the card or needle. The apertures of the kettle or pan already
described are to be glazed with glass or ising-glass, to prevent the wind and
weather disturbing the motion of the card.
To find the magnetic variation by this compass the method is as follows:-
Place the beginning of the vernier divisions to 0 on the septant, or to 0 on
oric end or other of the octant, as the case may require. See that the
horizon glass and the index revolving glass are well adjusted together; look
directly up at the sun, or moon, or star, through the unsilvered part of the
horizon glass, by means of the tangent screw or endless screw, or other
-method adopted for giving the glass its motion on its centers, being the
sun, moon, or star, down to the horizon; then ease the tightening screw, and
.bring the sun, moon, or star from the right or left, as the case may be, by
reflexion in the horizon glass to the line of coincidence of the threads seen
by direct vision through the unsilvered part of the horizon glass, and the
index will then shew the magnetic bearing or azimuth, which, when compared
to the true azimuth, will determine the variation.
In witness whereof, I have hereunto set my hand and seal, the Sevent!
day of April, in the year of our Lord One thousand seven hundre
and ninety-four.

page_text: AND BE IT REMEMBERED, that on the Ninth day of April, in the
year of our Lord 1794, the aforesaid Patrick Rooney Nugent came before
our said Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stampt according to
the tenor of the Statutes made for that purpose.
Inrolled the Ninth day of April, in the year of our Lord One thousand
seven hundred and ninety-four.

page_text: NUGENT'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PATRICK
ROONEY NUGENT, late Cheif Surveyor of Crown Lands in the Island of
Cape Breton, in North America, but now of Gray's Inn, in the County of
Middlesex, Esquire, send greeting.
WHEREAS His most Excellent Majesty King George did, by His Letters
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Eighteenth day of March, in the thirty-fourth year of His reign, give
and grant unto me, the said Patrick Rooney Nugent, His special licence
that I, the said Patrick Rooney Nugent, during the term of years therein
mentioned; should and lawfully might use, exercise, and vend, within England,
Wales; and the Town of Berwick-upon-Tweed, my Invention of "Two-In-
STRUMENTS WHEREBY THE LATITUDE, LONGITUDE, AND MAGNETIC VARIATION AT SEA
OR ON SHORE MAY BE OBTAINED;" in which Letters Patent is contained a proviso
obliging me, the said Patrick Rooney Nugent, by an instrument in. writing
under my hand and seal, to cause a particular description of the nature of
my said Invention, and in what manner the same is to be performed, to be
inrolled in His Majesty's High Court of Chancery within one calendar month
next after the date of the said recited Letters Patent, as in and by the same,
relation being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Patrick Rooney Nugent, do hereby declare that my said Invention is used in
manner following (that is to say) :-
The instruments as delineated on the margin hereof consist, first, of an
universal reflecting septant, sextant, oxtant, or quadrant of a glass tubb and

page_text: bubble, and of a pendulum for taking altitudes without an horizon; and,
secondly, of a steering or universal azimuth compass. The arch of the septant
contains two hundred reflected degrees, and is divided and numbered from
the centre, at which is placed 0 degrees; from thence to either extremity of
the circle it is marked or numbered regularly 5, 10, 15, 20, 25, 30, &c.,
to 100. This instrument hath an index with a vernier or nonices, which is
also divided and numbered from its middle or center, and so as to read either
way. The heads of the clamp screw and tangent screw, on the end of tho
index, are both on top; the former being opposite the middle of the nonices,
and the head of the latter next the observer, in case there is an handle at the
back of the instrument as usual, otherwise they are better as they are com-
monly fixt and made. On the head of the index is a circular plate, confined
to the index by means of two scutcheons placed on or to the centre, the
lowermost of which is a square and the other a round scutcheon; or it may
be confined by any other method judged best. The head of the index, instead
of being cast or filed round, bath a small projection at the head thereof of about
half an inch, and of the width of about three fourths of an inch, which projec-
tion is a little distance before the center line or direction of the bar of the index.
Upon this projection is fixed an endless screw, by means of a clamp screwed
down to the former projection, which screw acts in a grove or sort of fine
rackwork, cut or made out of the upper edge of the circular plato already
mentioned, by a screw engine, to answer the threads of the endless screw
aforesaid, and by which endless screw the plate and the several matters thereon,
herein-after described, are horizontally adjusted as need may require. The
head of the endless screw aforesaid is placed next the observer. On the plate
before described is fixed or fastened two speculums or glasses, the lower glass
of which is made fast at right angles to the plane of the instrument, as usual
in Hadley's sextants; but it will be more form to have this glass slide into a
dovetail frame or solid case, having a grove made in it for the glass to slide
upwards into, and a small slip of brass soldered or made fast with screws to
the head of the aforesaid solid frame or case, to confine and protect the upper
edge of the glass, and any method judged best to steady it there. The upper
glass is confined in a clip or case open at the lower end, a slip of brass of
about equal size with the glass, and having four pius or points near the angles
of its ends, to prevent the silvering of the glass from being injured, and having
a case which projects therefrom upwards about the same height as the thick-
ness of the glass. This slip or piece of brass is introduced with the glass
thereon, or in front of it, up into the former case or clip, and both confined
therein by means of two small screws partly introduced through the back of

page_text: the aforesaid clip or case. This glass acts upon two centers made fast or
soldered to the sides of its frame or clip, and which centers pass through and
are confined in two pieces fastened with screws, or otherwise, to the sides of
the lower frame, and to a part of its back if found necessary. The middle
or center of these centers are to be opposite the horizontal line herein-after
mentioned to be drawn on the back of this glass. The uppermost of those
pieces (when the instrument is adjusted for taking altitudes or angles by
double reflection) hath a semicircular broad part at the upper part thereof,
(which projects backwards from the front of the glass), of at least eight
tenths of an inch radius, which must be divided into reflected degrees, so far
as to allow the observer, by assistance of the vernier belonging thereto, to read
of of about one hundred degrees. These degrees, as well as the vernier
divisions, are to be numbered from the observer when he looks at the face
or front of the glass, and to commenco together when the glass is adjusted
perpendicular to the plane of the instrument. The vernier or nonices just
mentioned is fixed by means of screws to the upper part of the frame of the
glass. The motion of this glass on its centers is made by means of a tangent
screw placed opposite to the center of the glass, the shank part or head of
which screw acts in a poppet fastened into the upper part of a small arm or
other contrivance mado fast to the back part of the frame, or to the case of
the frame of the lower glass, by means of screws or soldering, no part of which
arm must extend higher than the upper edge of the frame of the lower glass.
The point parts of said screw is made fast or confined by means of another
small poppet, fastened into a picce made fast to the upper part of the frame
of the glass; or the tangent screw may be inverted, or its motion may be given
by an endless screw working in a rack, cut out of the upper edge of the semi-
circular piece aforesaid, or by any other of the various methods already suffi-
ciently well known. The horizon glass hath two silvered parts, and an open
parallel space to the plane of the instrument between them; the lower part
is used with the lower index glass in all respects as Hadley's horizon and
index glasses are, but the upper is to be used with the upper index glass.
This horizon glass hath need of no horizontal adjustment, but its vertical
adjustment may be by any of the methods already sufficiently known, or such
other found most convenient. The back surfaces of the lower and upper glass
are equally divided by a perpendicular line drawn on them. The back surface
of the upper glass is also equally divided by another line drawn horizontally
thereon; the reflexion of this latter line, when the glass is vertically adjusted,
defines the lower part of the upper silvering of the horizon glass, and the
reflexion of the upper edge of the lower index glass will define the upper edgo

page_text: of the lower silvered part of the horizon glass; the space between ought to be
unsilvered, and the lower glass ought to be made so small and the upper
glass so large as to admit this space to be sufficient for all observations to
be made with this instrument. The sizes of the glasses hereby described will
be therefore nearly as follows:-Cower index glass, one and three fourths
inches in width by one inch in heighth; upper indox glass, one and three
fourths inches in width by eight & one half tenths of an inch in height;
height of the lower part of the silvering of the horizon glass, six tenths of an
inch height of the upper silvered part, four tenths of an inch, and the unsilvered
space between, three tenths of an inch; as to the width of the horizon glass,
it should not exceed one inch and two tenths of an inch. The situation of
the horizon glass and telescope or plane sight are in a great manner discre-
tionary, but the most convenient and useful in a twelve-inch instrument of
this kind will be nearly as follows: The telescope four inches and seven tenths
of an inch from the center, and the horizon glass five inches and six tenths
of an inch; they must be otherwise so placed as not to interrupt the motion
of the index to the reading off the divisions to the end of the arch. The
telescope and its adjustment are the same as is usual, save that there must
be two shades placed therein, to protect the eyes from the lustre of the sun
in taking its altitude without an horizon or a back observation, and that it
should adjust so high as the upper part of the upper index glass. To take
an altitude without an horizon by this instrument there are two methods, both
of or on the same principles, namely, that of gravitation. The first is by a
perfectly circular cylindrical concave glass tube, the most conveniant size of
which for the instrument and observer will be found about seven and an half
inches radius, one fifth of an inch concavity, and one fifth of an inch thick;
this tube, to be eased with brass, excepting about three tenths of an inch of
the surface next the center, which should be a little more in length than a
quarter of a circle, is to be so placed when used, that the lower part or sur-
face of its concavity form a perfect portion of a circle in respect to the center
of the instrument, and the height of its upper surface be about an inch and
a quarter fron the plane of the instrument; and when its inner surface or
concavity is perfectly clear, a bubble of thoroughly pure clear quicksilver or
mercury is put and used therein. When a pendulum is designed for this
instrument, either the case of the frame of the lower index glass must be
made sufficiently thick, or another plate of little more than semicircular form
is placed over the circular plate already described, which plate must be about
one fifth of an inch in thickness; this plate, or the case aforesaid, must be
so hollowed out in front as to permit the free vibrations of the pendulum in

page_text: aking altitudes from the horizon up to the zenith; the center of the instru-
nent which before only extended even with the upper surface of the circular
late already mentioned, must in this case extend through the base of the
rame of the lower index glass, or through the nearly semicircular plate just
lescribed. This additional or increased length of center supports the pen-
Julum, which is best made in two parts, the shorter of which, of about three
inches in length, always to remain on the center, and the other part to be
occasionally attached thereto by means of a finger screw and two steady pins.
This part last mentioned hath a semi-globular ball attached to its extreme under
end bejond the arch of the instrument, and on the flat upper face of which
slides off and on occasionally a vertical plane slide of about one and an half
inch in height and six tenths of an inch wide. On the middle of this slide is
drawn a line, which line, when the index is set to 0, and the instruinent
adjusted for taking altitudes without an horizon, and the observer looks at the
horizon, he should by single reflection perceive in the under index glass level
with the surface of the sea. Withinside or near the center of the instru-
ment than the semi-ball aforesaid, and on the under surface of the pen-
dulum, is fixed four friction rollers, in two small brass pieces; these are to
play freely on the further part from the center of the arch of the instrument,
two over and two under. The whole mounting herein already described,
brass and glasses, may be placed as already set forth on any arch whatever,
whether of a sextant or quadrant, but the most conveniant lesser size will be
that of the universal reflecting octant. This instrument contains an arch of
about one hundred and ten degrees, but it is not divided or figured from the
center as the septant already described is, but from a littlo distance before
the limbs backwards and forwards. Thus the first space of ten or more
degrees of divisions, on the lower line next the observer, must be marked
backwards 0, 5, 10, &c.; then the said lower line is to be regularly figured
forwards from the aforesaid 0, or the observer, 5, 10, 15, 20, &c., to 100, or as
far as the arch extends; over the 100 just mentioned is marked 10, then 5,
then 0, which 0 will fall over the 90s of the former, numbering them
5, 10, 15, 20, &c., to 100, or as far as the arch runs, which 100 will fall over
the 10 backward numbering of division first mentioned; by this means the
degrees within the two 90' are made the complements of each other; then, by
5 setting the beginning of the vernier divisions to 0 on either end of the arch,
the index glasses are adjusted to the horizon glass by means of the endless
screw and plate already described. But altitudes without an horizon cannot be
conveniently taken near the horizon by means of the glass tube and bubble

page_text: aforesaid, nor by means of the pendulum applied to this instrument, except so
far as the glass tube extends over the face of the instrument, or that the
pendulum can freely vibrate or traverse. The method of taking altitudes
without an horizon by either, is as follows:-The glass tube or pendulum
being placed as before mentioned, set the beginning of the vernier divisions
to the near 90 on the septant, or to the nearest 0 on the octant; screw back
the upper glass so as to allow sufficient space for observation between it and
the upper edge of the lower glass, then direct the line of vision of the telescope
or plane right to the center line of the lower speculum, by means of the end-
less screw already described; adjust the lower speculum at right angles to the
line of vision; so is the instrument adjusted; look directly over the perpen-
dicular line drawn in the under glass at any object; move the index until
such time as the bubble aforesaid or the line drawn in the vertical plane
slido by single reflection in the upper edge of the lower glass is exactly hori-
zontal with the center of such object seen by direct vision over the said glass,
and tho index will then shew the altitude on the septant, or its zenith dis-
tance on the lower numbering of division on the octant. It hath been before
observed, that the lower index glass on either of these instruments is used
in the same manner as Hadley's sextant; but there are other uses to which
it may be applied in these instruments; thus, to take a back observation, set
the beginning of the vernier divisions to 0 on the septant, or 90 on the lower
figuring of divisions of the octant, and adjust the lower speculum at right
angles to the line of vision of the telescope, as before described for taking an
altitude without an horizon. Let the observer turn his back to the sun, and
look directly over the perpendicular line drawn in the under glass to the
surface of the sea before him, then drawing the index gently to him, until by
single reflection he brings the image of the sun to the horizon, the index will
then shew its altitude, proper allowance being made for his semi-diameter and
refraction on the septant, or its zenith distance on the lower figuring of the
divisions of the octant. The great and universal use of the upper glass is,
to measure any sort of other distances at the pleasure of the observer, as no
fixed glass can possibly measure other than direct distances or angles; but its
uses being so manifold in measuring horizontal or other distances between
objects of unequal altitudes, in taking the transits of objects at sea, in finding
the variation of the compass, and the latitude and longitude of places, that it
would require by far too much explanation to be confined in a Specification.
Here it must be carefully attended to, that if any person or persons who may
chuse to order an instrument of the aforesaid described Invention, but not

page_text: requiring to take altitudes without an horizon nor a back observation, that
in such case all that is necessary is, that these two index glasses (or one as
berein-after described) be placed on the same kind of index and plate and in
the same manner as is usually done in fixing one erect glass on Hadley's sex-
tant, and that the horizon glass have both an horizontal and vertical adjust-
ment. The index glass just alluded to is made after the same manner as the
upper glass already described; it hath its motion on its center by a tangent
scrow, the shank or part near the head of which acts in a poppet made
fast into the upper part of a small arm or other contrivance made fast to
its base by screws or soldering. The point of said screw is made fast or
confined by means of another small poppet affixed into a piece made fast near
the upper part of the frame (or its motion may be given by any of the other
methods already set forth), it hath a semicircular piece and a nonices, as the
aforesaid described upper glass hath; it hath morcover on the inner part of
the back of its nonices, if its motion is given by means of a tangent screw as
already described, a small spring and tightening screw to steady it the more
perfectly in any position, by pressing the spring by means of the tightening
screw aforesaid to the inner surface or back of its semicircular piece. This
single universal reflecting index glass, with an horizon glass silvered in two
parts, or in one part only, will perform all that both the aforesaid index
glasses will; for, when it is adjusted perpendicular to the plane of the instru-
ment, it will perform as an Hadley's sextant glass, and when it is reclined
backwards or forwards it will perform as the upper glass already described.
The future different make therefore of these instruments doth entirely depend
upon the different dispositions or choice of different persons, whilst the Inven-
tion remains the same, to wit: two index glasses instead of one as is usual,
and the upper glass having a motion on its axis or centers, to these must'
belong a double-silvered horizon glass, as already described, one index glass,
but not fixed as usual, having a motion on its axis or centers, and to which,
as being but one glass, an horizon glass silvered in one part only, will be
sufficient, a circular glass tube or a pendulum, such as herein already
described, and which, by single reflection, obtains altitudes without an horizon,
the size of the instruments, and manner of numbering the divisions on their
arches, with other particulars herein already set forth: these are the subjects
of the Invention. And as to the method of giving the motions already stated,
the difference of opinion of different workmen is of little avail in point of
nautical ascertainments, for if the motion is any how given by steady means,
it is perfectly sufficient.

page_text: The steerling or universal azimuth compass is made thus:-The height
of the pan or kettle, for a compass of eight inches diameter is about five
inches; an aperture of forty-five degrees horizontal width, and about one
inch and an half in height, is made or cut out of the side of the kettle
aforesaid, directly opposite each other, one half or one side and the other
half on the other side of each side of the shoulders or axis of the pan,
and immediately above them two plain sights of about one and an half inch
high, six tenths of an inch wide, and having an aperture in each of about
three tenths of an inch in width, and in the center of which is fixed a hair
or silk thread. These sights are to be firmly fixed by screws or dovetail, so 1
that the threads or hairs aforesaid will be exactly opposite to the north and
south points of the card or needle. The apertures of the kettle or pan already
described are to be glazed with glass or ising-glass, to prevent the wind and
weather disturbing the motion of the card.
To find the magnetic variation by this compass the method is as follows :—
.Place the beginning of the vernier divisions to 0 on the septant, or to 0 on
prie end or other of the octant, as the case may require. See that the
horizon glass and the index revolving glass are well adjusted together; look
directly up at the sun, or moon, or star, through the unsilvered part of the
horizon glass, by means of the tangent screw or endless screw, or other
-method adopted for giving the glass its motion on its centers, being the
sun, moon, or star, down to the horizon; then ease the tightening screw, and
.bring the sun, moon, or star from the right or left, as the case may be, by
reflexion in the horizon glass to the line of coincidence of the threads seen
by direct vision through the unsilvered part of the horizon glass, and the
index will then shew the magnetic bearing or azimuth, which, when compared
to the true azimuth, will determine the variation.
In witness whereof, I have hereunto set my hand and seal, the Seventh
day of April, in the year of our Lord One thousand seven hundred
and ninety-four.

page_text: AND BE IT REMEMBERED, that on the Ninth day of April, in the
year of our Lord 1794, the aforesaid Patrick Rooney Nugent came before
our said Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stampt according to
the tenor of the Statutes made for that purpose.
Inrolled the Ninth day of April, in the year of our Lord One thousand
seven hundred and ninety-four.

page_text: I NUGENT'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PATRICK
ROONEY NUGENT, late Cheif Surveyor of Crown Lands in the Island of
Cape Breton, in North America, but now of Gray's Inn, in the County of
Middlesex, Esquire, send greeting.
WHEREAS His most Excellent Majesty King George did, by His Letters
Patent under the Great Seal of Great Britain, bearing dato at Westminster,
the Eighteenth day of March, in the thirty-fourth year of His reign, give
and grant unto me, the said Patrick Rooney Nugent, His special licence
that I, the said Patrick Rooney Nugent, during the term of years therein
mentioned; should and lawfully might use, exercise, and vend, within England,
Wales; and the Town of Berwick-upon-Tweed, my Invention of "Two. IN-
STRUMENTS WHEREBY THE LATITUDE, LONGITUDE, AND MAGNETIC VARIATION AT SEA
OR ON SHORE MAY BE OBTAINED;" in which Letters Patent is contained a proviso
obliging me, the said Patrick Rooney Nugent, by an instrument in writing
under my hand and seal, to cause a particular description of the nature of
my said Invention, and in what manner the same is to be performed, to bo
inrolled in His Majesty's High Court of Chancery within one calendar month
next after the date of the said recited Letters Patent, as in and by the same,
relation being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Patrick Rooney Nugent, do hereby declare that my said Invention is used in
manner following (that is to say) :-
The instruments as delineated on the margin hereof consist, first, of an
universal reflecting septant, sextant, oxtant, or quadrant of a glass tubb and

page_text: bubble, and of a pendulum for taking altitudes without an horizon; and,
secondly, of a steering or universal azimuth compass. The arch of the septant
contains two hundred reflected degrees, and is divided and numbered from
the centre, at which is placed 0 degrees; from thence to either extremity of
the circle it is marked or numbered regularly 5, 10, 15, 20, 25, 30, &c.,
to 100. This instrument hath an index with a vernier or nonices, which is
also divided and numbered from its middle or center, and so as to read either
way. The heads of the clamp screw and tangent screw, on the end of the
index, are both on top; the former being opposite the middle of the nonices,
and the head of the latter next the observer, in case there is an handle at the
back of the instruinent as usual, otherwise they are better as they are com-
monly fixt and made. On the head of the index is a circular plate, confined
to the index by means of two scutcheons placed on or to the centre, the
lowermost of which is a square and the other a round scutcheon; or it may
be confined by any other method judged best. The head of the index, instead
of being cast or filed round, hath a small projection at the head thereof of about
balf an inch, and of the width of about three fourths of an inch, which projec-
tion is a little distance before the center line or direction of the bar of the index.
..Upon this projection is fixed an endless screw, by.means of a clamp screwed
down to the former projection, which screw acts in a grove or sort of fine
rackwork, cut or made out of the upper edge of the circular plate already
mentioned, by a screw engine, to answer the threads of the endless screw
aforesaid, and by which endless screw the plate and the several matters thereon,
herein-after described, are horizontally adjusted as need may require. The
head of the endless screw aforesaid is placed next the observer. On the plate
before described is fixed or fastened two speculums or glasses, the lower glass
of which is made fast at right angles to the plane of the instrument, as usual
in Hadley's sextants; but it will be more form to have this glass slide into a
dovetail frame or solid case, having a grove made in it for the glass to slide
upwards into, and a small slip of brass soldered or made fast with screws to
the head of the aforesaid solid frame or case, to confine and protect the upper
odge of the glass, and any method judged best to steady it there. The upper
glass is confined in a clip or case open at the lower end, a slip of brass of
about equal size with the glass, and having four pius or points near the angles
of its ends, to prevent the silvering of the glass from being injured, and having
a case which projects therefrom upwards about the same height as the thick-
ness of the glass. This slip or piece of brass is introduced with the glass
thereon, or in front of it, up into the former case or clip, and both confined
therein by means of two small screws partly introduced through the back of

page_text: the aforesaid clip or case. This glass acts upon two centers made fast or
soldered to the sides of its frame or clip, and which centers pass through and
are confined in two pieces fastened with screws, or otherwise, to the sides of
the lower frame, and to a part of its back if found necessary. The middle
or center of these centers are to be opposite the horizontal line herein-after
mentioned to be drawn on the back of this glass. The uppermost of those
pieces (when the instrument is adjusted for taking altitudes or angles by
double reflection) hath a semicircular broad part at the upper part thereof,
(which projects backwards from the front of the glass), of at least eight
tenths of an inch radius, which must be divided into reflected degrees, so far
as to allow the observer, by assistance of the vernier belonging thereto, to read
of of about one hundred degrees. These degrees, as well as the vernier
divisions, are to be numbered from the observer when he looks at the face
or front of the glass, and to commence together when the glass is adjusted
perpendicular to the plane of the instrument. The vernier or nonices just
mentioned is fixed by means of screws to the upper part of the frame of the
glass. The motion of this glass on its centers is made by means of a tangent
screw placed opposite to the center of the glass, the shank part or head of
which screw acts in a poppet fastened into the upper part of a small arm or
other contrivance made fast to the back part of the frame, or to the case of
the frame of the lower glass, by means of screws or soldering, no part of which
arm must extend higher than the upper edge of the frame of the lower glass.
The point parts of said screw is made fast or confined by means of another
small poppet, fastened into a piece made fast to the upper part of the frame
of the glass; or the tangent screw may be inverted, or its motion may be given
by an endless screw working in a rack, cut out of the upper edge of the semi-
circular piece aforesaid, or by any other of the various methods already suffi-
ciently well known. The horizon glass hath two silvered parts, and an open
parallel space to the plane of the instrument between them; the lower part
is used with the lower index glass in all respects as Hadley's horizon and
index glasses are, but the upper is to be used with the upper index glass.
This horizon glass hath need of no horizontal adjustment, but its vertical
adjustment may be by any of the methods already sufficiently known, or such
other found most convenient. The back surfaces of the lower and upper glass
are equally divided by a perpendicular line drawn on them. The back surface
of the upper glass is also equally divided by another line drawn horizontally
thereon; the reflexion of this latter line, when the glass is vertically adjusted,
defines the lower part of the upper silvering of the horizon glass, and the
reflexion of the upper edge of the lower index glass will define the upper edgo

page_text: of tho lower silvered part of the horizon glass; the space between ought to be
unsilvered, and the lower glass ought to be made so small and the upper
glass so large as to admit this space to be sufficient for all observations to
be made with this instrument. The sizes of the glasses hereby described will
bo therefore nearly as follows:-Cower index glass, one and three fourths
inches in width by one inch in heighth; upper index glass, one and three
fourths inches in width by cight & one half tenths of an inch in height;
height of the lower part of the silvering of the horizon glass, six tenths of an
inch: height of the upper silvered part, four tenths of an inch, and the unsilvered
space between, three tenths of an inch; as to the width of the horizon glass,
it should not exceed one inch and two tenths of an inch. The situation of
the horizon glass and telescope or plane sight are in a great manner discre-
tionary, but the most convenient and useful in a twelve-inch instrument of
this kind will be nearly as follows: The telescope four inches and seven tenths
of an inch from the center, and the horizon glass five inches and six tenths
of an inch; they must be otherwise so placed as not to interrupt the motion
of the index to the reading off the divisions to the end of the arch. The
telescope and its adjustment are the same as is usual, save that there must
be two shades placed therein, to protect the eyes from the lustre of the sun
in taking its altitude without an horizon or a back observation, and that it
should adjust so high as the upper part of the upper index glass. To take
an altitude without an horizon by this instrument there are two methods, both
of or on the same principles, namely, that of gravitation. The first is by a
perfectly circular cylindrical concave glass tube, the most conveniant size of
which for the instrument and observer will be found about seven and an half
inches radius, one fifth of an inch concavity, and one fifth of an inch thick;
this tube, to be cased with brass, excepting about three tenths of an inch of
the surface next the center, which should be a little more in length than a
quarter of a circle, is to be so placed when used, that the lower part or sur-
face of its concavity form a perfect portion of a circle in respect to the center
of the instrument, and the height of its upper surface be about an inch and
a quarter from the plane of the instrument; and when its inner surface or
concavity is perfectly clear, a bubble of thoroughly pure clear quicksilver or
mercury is put and used therein. When a pendulum is designed for this
instrument, either the case of the frame of the lower index glass must be
made sufficiently thick, or another plate of little more than semicircular form
is placed over tho circular plate already described, which plate must be about
one fifth of an inch in thickness; this plate, or the case aforesaid, must be
so hollowed out in front as to permit the free vibrations of the pendulum in

page_text: aking altitudes from the horizon up to the zenith; the center of the instru-
nent which before only extended even with the upper surface of the circular
plate already mentioned, must in this case extend through the base of the
rame of the lower index glass, or through the nearly semicircular plate just
described. This additional or increased length of center supports the pen-
dulum, which is best made in two parts, the shorter of which, of about threo
inches in length, always to remain on the center, and the other part to bo
occasionally attached thereto by means of a finger screw and two steady pins.
This part last mentioned liath a semi-globular ball attached to its extreme under
end bejond the arch of the instrument, and on the flat upper face of which
slides off and on occasionally a vertical plane slide of about one and an half
inch in height and six tenths of an inch wide. On the middle of this slide is
drawn a line, which line, when the index is set to 0, and the instrument
adjusted for taking altitudes without an horizon, and the observer looks at the
horizon, he should by single reflection perceive in the under index glass level
with the surface of the sea. Withinside or near the center of the instru-
ment than the semi-ball aforesaid, and on the under surface of the pen-
dulum, is fixed four friction rollers, in two small brass pieces; these are to
play freely on the further part from the center of the arch of the instrument,
two over and two under. The whole mounting herein already described,
brass and glasses, may be placed as already set forth on any arch whatever,
whether of a sextant or quadrant, but the most conveniant lesser size will be
that of the universal reflecting octant. This instrument contains an arch of
about one hundred and ten degrees, but it is not divided or figured from the
center as the septant already described is, but from a little distance before
the limbs backwards and forwards. Thus the first space of ten or more
degrees of divisions, on the lower line next the observer, must be marked
backwards 0, 5, 10, &c.; then the said lower line is to be regularly figured
forwards from the aforesaid 0, or the observer, 5, 10, 15, 20, &c., to 100, or as
far as the arch extends; over the 100 just mentioned is marked 10, then 5,
then 0, which 0 will fall over the 90' of the former, numbering them
5, 10, 15, 20, &c., to 100, or as far as the arch runs, which 100 will fall over
the 10 backward numbering of division first mentioned; by this means the
degrees within the two 90s are made the complements of each other; then, by
5 setting the beginning of the vernier divisions to 0 on either end of the arch,
the index glasses are adjusted to the horizon glass by means of the endless
.screw and plate already described. But altitudes without an horizon cannot be
conveniently taken near the horizon by means of the glass tube and bubble

page_text: aforesaid, nor by means of the pendulum applied to this instrument, except so
far as the glass tube extends over the face of the instrument, or that the
pendulum can freely vibrate or traverse. The method of taking altitudes
without an horizon by either, is as follows:-The glass tube or pendulum
being placed as before mentioned, set the beginning of the vernier divisions
to the near 90 on the septant, or to the nearest 0 on the octant; screw back
the upper glass so as to allow sufficient space for observation between it and
the upper edge of the lower glass, then direct the line of vision of the telescope
or plane right to the center line of the lower speculum, by means of the end-
less screw already described; adjust the lower speculum at right angles to the
line of vision; so is the instrument adjusted; look directly over the perpen-
dicular line drawn in the under glass at any object; move the index until
such time as the bubble aforesaid or the line drawn in the vertical plane
slide by single reflection in the upper edge of the lower glass is exactly hori-
zontal with the center of such object seen by direct vision over the said glass,
and the index will then show the altitude on the septant, or its zenith dis-
tance on the lower numbering of division on the octant. It hath been before
observed, that the lower index glass on either of these instruments is used
in the same manner as Hadley's sextant; but there are other uses to which
it may be applied in these instruments; thus, to take a back observation, set
the beginning of the vernier divisions to 0 on the septant, or 90 on the lower
figuring of divisions of the octant, and adjust the lower speculum at right
angles to the line of vision of the telescope, as before described for taking an
altitude without an horizon. Let the observer turn his back to the sun, and
look directly over the perpendicular line drawn in the under glass to the
surface of the sea before him, then drawing the index gently to him, until by
single reflection he brings the image of the sun to the horizon, the index will
then shew its altitude, proper allowance being made for his semi-diameter and
refraction on the septant, or its zenith distance on the lower figuring of the
divisions of the octant. The great and universal use of the upper glass is
to measure any sort of other distances at the pleasure of the observer, as no
fixed glass can possibly measure other than direct distances or angles; but its
uses being so manifold in measuring horizontal or other distances between
objects of unequal altitudes, in taking the transits of objects at sea, in finding
the variation of the compass, and the latitude and longitude of places, that i
would require by far too much explanation to be confined in a Specification
Here it must be carefully attended to, that if any person or persons who may
chuse to order an instrument of the aforesaid described Invention, but no

page_text: requiring to take altitudes without an horizon nor a back observation, that
in such case all that is necessary is, that these two index glasses (or one as
herein-after described) be placed on the same kind of index and plate and in
the same manner as is usually done in fixing one erect glass on Hadley's sex-
tant, and that the horizon glass have both an horizontal and vertical adjust-
ament. The index glass just alluded to is made after the same manner as the
upper glass already described; it hath its motion on its center by a tangent
screw, the shank or part near the head of which acts in a poppet made
fast into the upper part of a small arm or other contrivance made fast to
its base by screws or soldering. The point of said screw is made fast or
confined by means of another small poppet affixed into a piece made fast near
the upper part of the frame (or its motion may be given by any of the other
methods already set forth), it hath a semicircular piece and a nonices, as the
aforesaid described upper glass hath; it hath morcover on the inner part of
the back of its nonices, if its motion is given by means of a tangent screw as
already described, a small spring and tightening screw to steady it the more.
perfectly in any position, by pressing the spring by means of the tightening
screw aforesaid to the inner surface or back of its semicircular piece. This
single universal reflecting index glass, with an horizon glass silvered in two
parts, or in one part only, will perform all that both the aforesaid index
glasses will; for, when it is adjusted perpendicular to the plane of the instru-
ment, it will perform as an Hadley's sextant glass, and when it is reclined
backwards or forwards it will perform as the upper glass already described.
The future different make therefore of these instruments doth entirely depend
upon the different dispositions or choice of different persons, whilst the Inven-
tion remains the same, to wit: two index glasses instead of one as is usual,
and the upper glass having a motion on its axis or centers, to these must
belong a double-silvered horizon glass, as already described, one index glass,
but not fixed as usual, having a motion on its axis or centers, and to which,
as being but one glass, an horizon glass silvered in one part only, will be
sufficient, a circular glass tube or a pendulum, such as herein already
described, and which, by single reflection, obtains altitudes without an horizon,
the size of the instruments, and manner of numbering the divisions on their
arches, with other particulars herein already set forth: these are the subjects
of the Invention. And as to the method of giving the motions already stated,
the difference of opinion of different workmen is of little avail in point of
nautical ascertainments, for if the motion is any how given by steady means,
it is perfectly sufficient.
..

page_text: The steerling or universal azimuth compass is made thus:-The height
of the pan or kettle, for a compass of eight inches diameter is about five
inches; an aperture. of forty-five degrees horizontal width, and about one
-inch and an half in height, is made or cut out of the side of the kettle
aforesaid, directly opposite cach other, one half or one side and the other
half on the other side of each side of the shoulders or axis of the pan,
.and immediately above them two plain sights of about one and an half inch
high, six tenths of an inch wide, and having an aperture in each of about
three tenths of an inch in width, and in the center of which is fixed a liair
or silk thread. These sights are to be firmly fixed by screws or dovetail, so
that the threads or hairs aforesaid will be exactly opposite to the north and
south points of the card or needle. The apertures of the kettle or pan already
described are to be glazed with glass or ising-glass, to prevent the wind and
weather disturbing the motion of the card.
To find the magnetic variation by this compass the method is as follows:-
Place the beginning of the vernier divisions to 0 on the septant, or to 0 on
prie end or other of the octant, as the case may require. See that the
horizon glass and the index revolving glass are well adjusted together; look
directly up at the sun, or moon, or star, through the unsilvered part of the
horizon glass, by means of the tangent screw or endless screw, or other
-method adopted for giving the glass its motion on its centers, being the
sun, moon, or star, down to the horizon; then ease the tightening screw, and
bring the sun, moon, or star from the right or left, as the case may be, by
reflexion in the horizon glass to the line of coincidence of the threads seen
by direct vision through the unsilvered part of the horizon glass, and the
index will then shew the magnetic bearing or azimuth, which, when compared
to the true azimuth, will determine the variation.
In witness whereof, I have hereunto set my hand and seal, the Sevent!
day of April, in the year of our Lord One thousand seven hundre

page_text: AND BE IT REMEMBERED, that on the Ninth day of April, in the
year of our Lord 1794, the aforesaid Patrick Rooney Nugent came before
our said Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stampt according to
the tenor of the Statutes made for that purpose.
Inrolled the Ninth day of April, in the year of our Lord One thousand
seven hundred and ninety-four.