A. NEW IMPROVEMENT OF THE HADLEY'S QUADRANT AND SEXTANT, BEING AN APPARATUS OR INSTRUMENT TO BE AFFIXED THERETO AT PLEASURE, WHEREBY A TRUE, JUST, OR EFFECTUAL HORIZON CAN BE ARTI- FICIALLY OBTAINED, NOTWITHSTANDING THE REAL OR NATURAL HORIZON SHOULD BE PREVENTED FROM BEING SEEN BY THE INTERPOSITION OF LAND FOGS OR THICK WEATHER
Year: 1791

page_text: TO, ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY OULD,
of Dartmouth, in the County of Devon, Mathematical Instrument Maker, send
greeting.
WHEREAS His present Majesty, King George the Third, has been
graciously pleased to grant unto me His Royal Letters Patent under the Great
Seal of Great Britain, bearing date at Westminster, the Seventeenth day of
December last, for the using, exercising,, and vending of an Invention and
Discovery made by me, that is to say, "A. NEW IMPROVEMENT OF THE HADLEY'S
QUADRANT AND SEXTANT, BEING AN APPARATUS OR INSTRUMENT TO BE AFFIXED
THERETO AT PLEASURE, WHEREBY A TRUE, JUST, OR EFFECTUAL HORIZON CAN BE ARTI-
FICIALLY OBTAINED, NOTWITHSTANDING THE REAL OR NATURAL HORIZON SHOULD BE
PREVENTED FROM BEING SEEN BY THE INTERPOSITION OF LAND FOGS OR THICK WEATHER;"
and in which said Royal Letters Patent is contained a provisoe that if I, the
said Henry Ould, should not particularly describe and ascertain the nature of
my said Invention, and in what manner the same is to be performed, by an
instrument in writing under my hand and seal, and cause the same to be
inrolled in His Majesty's High Court of Chancery within one calender month
next and immediately after the date of those His said Majesty's Letters Patent,
that then those the said Majesty's Letters Patent, and all liberties and advan-
tages whatsoever thereby granted, should utterly cease, determine, and become
void.
NOW THEREFORE I, the said Henry Ould, in pursuance of such provisoc
contained in the said Royal Letters Patent, do hereby declare and certify

page_text: that what is hereafter set forth doth particularly describe and ascertain the
nature of the said Invention, and in what manner the same is to be performed,
that is to sny:-
A pendulum, marked in the Plan A, with its axis, marked B, both ends of
which axis plays in a center; or such axis may be made to play in collars, from
which axis is fixed a round plate, marked D, whereon is fixed an index, marked
at bottom and top of it with Letter E, to move centrically on such round plate
by means of an adjusting screw, marked F; which index hath two vanes, cach
marked G, made to slide in dovetails thereon, the uppermost of which vanes
bas a piece of ivory riveted or screwed on it, thro' the middle of which ivory
longways is drawn a fine line, made black, and the lowermost of which vanes
is open, and has a hair or fine wire liue fixed longways in the middle of it, and
which two vanes are so malo to slide in dovetails on the index, in order occn-
sionally, to move their distance from each other. This apparatus or instrument
is supported by a frame, marked H, in three places, which is fastned by a
finger-screw, marked I, and two steady pins to a cock, marked K, which cock
is fixed in the head of a quadrant or sextant, behind the index glass, to receive
such apparatus or instrument. The pendulum, for conveience, is made to lock
on at pleasure by two studs, marked L, L, and vibrates at the back of the
quadrant or sextant, where it is protected from being injured by superfluous
motions by a guard fastued across the back of such quadrant or sextant,
marked M. The whole of this apparatus is made in brass, or can be made in
other metal. The horizon glass to the quadrant or sextant must have three
divisions, two of them that are marked N and O are to be silvered, and
the other, marked P, to be transparent, which transparent part is to be between
the two silvered parts, as represented in the Plan; the outer silver parts must
not have any line drawn thro' it, but the transparant and the inner silver part
must have a line drawn thro' the middle of them, as represented in the
Plan.
To adjust the above instrument :-
The above instrument being screwed to the head of a Hadley's quadrant or
sextant just behind the index glass, by means of the finger screw, adjust it to a
good natural horizon; thus, having set the vanes on the index, which move in
dovetails, at equal distances from the middle of the index, let the pendulum
swing at pleasure, then look through the sight hole of the quadrant or sextant,
and bring the line that runs through the transparent division of the horizon
glass truly on such good natural horizou, and then, by means of the adjusting
Screw, move the index wherein the two vanes slide, backwards or forwards, til
you see the line that runs thro' the middle of each vaue reflect themselves and

page_text: appear as one line only in the outer quicksilver part of the horizon glass; and
when they so therein appear in one line, observe that the line in the horizon
glass must also be on the real or natural horizon.
This index with the two vanes thereon being once thus well and truly adjusted
by means of and to a good natural horizon, will, at all times hereafter,
when you chose to screw the aparatus or instrument on to the quadrant or
sextant, shew or serve as a truc, just, or effectual horison, whether the natural
horizon be seen, or whether the same cannot be seen by the interposition of
land fogs or thick whether, unless the index or adjusting screw should be
accidentally or otherwise altered to ascertain which, and to prevent the trouble
of a new adjustment, after it has been once well and truly adjusted with a
certain good horizon, draw a line with a sharp-pointed instrument on the round
plate close to the bottom of either edge of the index that turns on the round
plate, which will show if it has been altered, and also enable you, if it has,
to set the index in its true position again.
This apparatus being once thus truly adjusted, the method of taking the
sun's altitude is as follows:-
Hold the quadrant or sextant with your left hand in such possition that by
looking thro' the sight hole you see or bring the lines that runs thro' the two
vanes to reflect or appear as one in the outer quicksilver part of the horizon
glass, which, when they so do, gives you the true direction of the quadrant or
sextant with the real horizon; then, bringing the image of the sun down on the
line in the horison glass by moving the index, the quadrant, or sextant, as done
in taking observations, it gives you the sun's true altitude from the real
horizon. The two vanes on the index may be kept at their greatest distance
or brought nearer to each other, when you take an observation, according to
the case or rolling of the ship; that is to say: if the ship rolls much, to put
the vanes a little nearer to each other; if otherwise, they may remain at their
greatest distance; for the nearer they are, the effect of the ship's motion is
lessened.
In witness whereof, I have hereunto set my hand and seal, the Sixteenth
day of January, in the thirty-second year of the reign of our Sovereign
Lord George the Third, by the grace of God of Great Britain, France,
and Ireland King, Defender of the Faith, &c., and in the year of our
Lord One thousand seven hundred and ninety-two.
HENRY (L.S.) OULD.
Signed, sealed, and delivered (being first
duly stampt) in the presence of
JOHN EDWARDS, New Bridge Street, London, Gent"
ROGER MELLOR. same place Gent

page_text: AND BE IT REMEMBERED, that on the Sixteenth day of January, in the
year of our Lord One thousand seven hundred and ninety-two, the aforesaid
Henry Ould 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. stamped according to the tenor of the Statutes made for that
purpose.
Inrolled the Sixteenth day of January, in the year of our Lord One
thousand seven hundred and ninety-two.