A QUADRANT FOR TAKING OBSERVATIONS AT SEA
Year: 1760

page_text: WINTER, DOLLOND, SCATLIFFE, AND GREGORY'S
SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, THOMAS
WINTER the elder, of Liverpool, in the County of Lancaster, Marriner, JOHN
DOLLAND, of the Strand, in the County of Middlesex, Optician, DANIEL
SCATLIFF, of the Parish of Saint John. Wapping, in the said County of
Middlesex, Ship Chandler, and HENRY GREGORY, of the City of London,
Mathematical Instrument Maker, send greeting,
WHEREAS by Letters under the Great Seal of Great Britain, bearing date
at Westminster, the Second day of October, in the thirty-fourth year of the
reign of His late Majesty King George the Second, reciting that the said
Thomas Winter the elder, John Dolland, Daniel Scatliffe, and Henry Gregory,
had, by their Petition, humbly represented unto His said Majesty that they,
after much study, labour, and expence, had invented "A QUADRANT FOR
TAKING OBSERVATIONS AT SEA;" that in regard the same might be of great
benefit and advantage to the subjects, they therefore humbly prayed that His
said Majesty would be pleased to grant to them, their executors, administra-
tors, and assigns, His Royall Letters Patent for the sole use and benefit of their
said Invention, in England, the Dominion of Wales, Town of Berwick-upon-
Tweed, and Plantations and Colonys abroad, for the term of fourteen years, as
thereby mentioned; His said late Majesty, for Himself, His heirs and succes-
sors, did give and grant unto the said Thomas Winter the elder, John Dolland,

page_text: Daniel Scatliff, and Henry Gregory, their executors, administrators, and
assigns, and every of them, especial licence, full power, sole priviledge and
authority, that they, their executors, administrators, and assigns, and every of
them, by himself and themselves, or by his and their deputy or deputies,
servants or agents, or such other as they should agree with, at all times during
the term of years therein expressed, should and lawfully might make, use,
exercise, and vend, their said Invention within that part of Great Britain
called England, the Dominion of Wales, and Town of Berwick-upon-Tweed,
and the Plantations and Colonies in America, in such manner that they, their
executors, administrators, and assigns, should and lawfully might have and
enjoy the whole benefit, profit, comodity, and advantage from time to time
coming, growing, accruing, and arising by reason of the said Invention, for
and during the term of years therein mentioned, to hold, exercise, and enjoy
the said licence, powers, priviledges, and advantages thereby granted unto the
said Thomas Winter the elder, John Dolland, Daniell Scatliff, and Henry
Gregory, their executors, administrators, and assigns, for and during and unto the
full end and term of fourteen years from the date thereof, fully to be compleat
and ended, according to the Statute in such case made and provided; in which
said Letters Patent (amongst other things) is contained a provisoe to the
effect following, (that is to say), that if they, the said Thomas Winter the
elder, John Dolland, Daniel Scatliffe, and Henry Gregory, should not par-
ticularly describe and ascertain the nature of their said Invention, and in
what manner the same is to be performed, by an instrument in writing
under their hands and scals, and cause the same to be inrolled in the High
Court of Chancery within four calendar months next and immediately after
the date of the said Letters Patent, then the said Letters Patent, and all
liberties and advantages whatsoever thereby granted, should utterly cease,
determine, and become void, anything therein-before contained to the con-
trary in anywise notwithstanding, as in and by the said in part recited Letters
Patent, relation being thereunto had, will more fully appear.
NOW KNOW YEE, that in pursuance of the said proviso for describing and
ascertaining the nature of the said Invention, they, the said Thomas Winter
the elder, John Dolland, Daniel Scatliff, and Henry Gregory, and each and
every of them, do, in compliance with the said provisoe, by these Presents set
forth and discover the nature and use of the said Invention to be in manner
and form following (that is to say):-
The artificial horizon applied to Hadley's quadrant is of two kinds; (that is
to say), the one to take the altitudes in the day time, and the other for the
same purpose in the night; that used in the day time is performed by a spirit

page_text: level fixed upon the outer limb of the quadrant, and in order to its being seen
by the observer as he is viewing the sun's image, there must be a small mirror
placed behind the transparent part of the horizon glass at such an angle as to
make the level appear straight before the observer, and the bubble of air
exactly at the height of the horizon; the bubble is rendered distinct to the
observer's sight by a convex lens situated directly under the same mirror, so
that the line of vision may pass through it. But the principal contrivance is
the curvature of the level, which must be adapted to its distance from the eye
so as to cause the bubble to appear always at the same height at whatsoever
part of the horizon glass the observation is taken. That used in the night
time is performed by a pendulous mirror fixed to an axis on which it has a
small motion regulated by a pendulum, but the pendulum must not be suffered
to vibrate far; when the quadrant is held steady and pretty near the middle of
the pendulum's vibration, the pendulous mirror will become parrellel to the
horizon glass, and being fixed behind the transparent part thereof, the same
objects, whether the moon, starrs, or any of the planetts, will be seen in it as
is seen in the horizon glass, therefore the observation is made by moving the
index till the starr is brought down to the horizon, which will be known by
seeing it in both mirrors at once, that is, in the horizon glass and in the pen-
dulous mirror behind it. And in order that the observation may be equally
true in all parts of the horizon glass, the pendulous mirror must be ground
cylindrical, of a radius equall to its distance from the eye.
In witness whereof, they have hereunto sett their hand and seals, the
Tenth day of January, in the year of our Lord One thousand seven
hundred and sixty-one.

page_text: AND BE IT REMEMBRED, that on the Tenth day of January, in the
first year of the reign of His Majesty King George the Third, the said John
Dollond, Daniel Scatliffe, and Henry Gregory, came before our said Lord the
King in His Chancery, and acknowledged the Writing aforesaid, and all and
every matter and thing therein contained, in form above said.
AND ALSO BE IT REMEMBRED, that on the Thirteenth day of the said
January, in the year aforesaid. the said Thomas Winter came before our said
Lord the King in His Chancery, and acknowledged the Writing aforesaid, and
all and every matter and thing therein contained, in form above said. And also
the said Writing was stamped according to the Statute made in the sixth year
of the reign of King William and Queen Mary of England, and so forth.
Inrolled the Nineteenth day of January, in the first year of the reign of
NET 'OUT
YT
PTT LLL