NEW-INVENTED MARINE OBSERVATORY, AND NEW- ADAPTED TELESCOPE AND ALMANACK, BY WHICH THE LONGITUDE AT SEA MAY BE ASCERTAINED IN A FAR MORE PLAIN, EASY, AND EXACT MANNER THAN HAS HITHERTO BEEN DISCOVERED, AND BE IN SEVERAL OTHER RESPECTS USEFUL IN NAVIGATION
Year: 1758

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHRISTOPHER
IRWIN, of Suffolk Street, in the Parish of Saint Martin in the Fields, in the
County of Middlesex, Esquire, send greeting.
WHEREAS His most Excellent Majesty King George the Second, by
His Letters Patent under the Great Seal of Great Britain, bearing date the
Second day of December, in the thirty-second year of His said Majesty's
reign, did give and grant to me, the said Christopher Irwin, His special
license, full power, ole priviledge, and authority, that I, the said Christopher
Irwin, my exors, adiñors, and assigns, should and lawfully might, during the
term of years therein expressed, use, exercise, and vend, throughout that part
of His Majesty's Kingdom of Great Britain called England, the Dominion of
Wales, and Town of Berwick-upon-Tweed, and also in His Majesty's Plan-
tations and Colonys, my "NEW-INVENTED MARINE OBSERVATORY, AND NEW-
ADAPTED TELESCOPE AND ALMANACK, BY WHICH THE LONGITUDE AT SEA MAY BE
ASCERTAINED IN A FAR MORE PLAIN, EASY, AND EXACT MANNER THAN HAS HITHERTO
BEEN DISCOVERED, AND BE IN SEVERAL OTHER RESPECTS USEFUL IN NAVIGATION;" in
which said recited Letters Patent is contained a provisoe obliging me, the
said Christopher Irwin, by writing under my hand and seal, to cause a par-
ticular description of the nature of the said Invention to be inrolled in His
Majesty's High Court of Chancery within four calender months after the
date of the said recited Letters Patent, as in and by the Statute, relation
being thereunto had, may more at large appear.
NOW KNOW YE, that in compliance with the said provisoe, I, the said
Christopher Irwin, do hereby declare that my said new Invention is composed
and made in manner following (that is to say):-
-

page_text: The marine observatory consists of a stage or seat for an observor, his
telescope or other instruments, fixed over deck at right angles, with a stiff
pendulum, which passes under deck with a heavy weight fixed to the lower
end thereof near the seat. The pendulum is suspended very glibly by cross
axes or ball and sockets, and otherwise, so as by the centripetal force of the
weight below to procure for the seat, &c., a center of motion distinct from that of
the ship, and thereby to counteract the tossings of the ship, so as to keep the
observatory horizontal, or tranquil enough for the purposes of observation.
The new-adapted telescope, with or without its micrometer, as occasion may
require, is self-poized in a frame fixed to the above-mentioned plane, which
being counterpoized and turning glibly upon axes, the observer may with
ease move the telescope in all directions, and it will continue in any direction
desired. To the outside of the telscope is fixed a guide, by which means to
point at the object with one eye, and almost at the same instant to see it in
the telescope with the other. The almanack of longitude is to consist of
diurnal tables, with collumns shewing the celestial appearances, &c., with the
encreasing and decreasing varietys, and all the necessary corrections by which
the hour of the absent place may be known. 'Tis to begin from a certain mid-
day of a certain place, and to be computed to that place. Tis to direct the
management of the marine observatory telescope and other instruments of
observation, and is computed to the equator, so that fewer observations and
less trouble in computation will be necessary.
In witness whereof, I have hereunto set my hand and seal, this Four-
teenth day of March, in the year of our Lord One thousand seven
hundred and fifty-nine.

page_text: And
AND BE IT REMBRED, that the Fourteenth day of March, in the year
above written, the aforesaid Christopher Irwin came before our said Lord the
King in Ilis Chancery, and acknowledged the Invention aforesaid, and all
and every thing therein contained and specified, in form above written.
also the Invention aforesaid was stampt according to the tenor of the Statute
made in the sixth year of the reign of the late King and Queen William and
Mary of England, and so forth.
Inrolled the Fourteenth day of March, in the year above written.