AN UNIVERSAL ASTRONOMICAL QUADRANT
Year: 1738

page_text: TO ALL TO WHOME THESE PRESENTS SHALL COME:
KNOW YE, that His present Majesty King George the Second of Great
Britain, and so forth, by His Letters Patent under the Great Seal, bearing date
at Westminster, the Twenty-first day of December, in the twelfth year of His
reign, have, for Himselfe, His heirs and successors, given and granted unto me,
JOHN BARSTON, of Battersea, in the County of Surry, Watchmaker, and to my
executors, administrators, and assigns, especial licence, full power, sole
privilege and authority, to make, use, exercise, and vend, within that part of
Great Britain called England, the Dominion of Wales, and Town of
Berwick-upon-Tweed, a certain instrument by me newly invented and called
"AN UNIVERSAL ASTRONOMICAL QUADRANT," together with the whole profit,
benefit, commodity, and advantage from time to time accrewing and arising by
reason of the said Invention, for and during and unto the full end and term of
fourteen years, according to the form of the Statute in that case made and
provided; in which said Letters Patents among other things it is provided that
if I, the said John Barston, shall not particularly describe and ascertain the
nature and form of my said Invention, in what manner the same is to be per-
formed, by an instrument in writing under my hand and seal, and cause the
same to be inrolled in the High Court of Chancery within three calendar
months next after the said day of the date of the said Letters Patent, that
then the said Letters Patent, and all liberties and advantages thereby granted,
should utterly cease, determine, and be void, anything before in the said
Letters Patent contained to the contrary in anywise notwithstanding.

page_text: THEREFORE FURTHER KNOW YEE, that I, the said John Barston, in
pursuance of the said proviso, have caused a Draught or Figure of my said new
invented instrument to be hereupon imprinted, together with several represen-
tations of the manner of using it, and do by these Presents further describe it
as follows (that is to say):-
The figure of it, as it appears by the said Print, is a semicircle with open
sights at each end of its diameter, which diameter from A to B is twenty
inches, and the radius from C to D is ten inches; half the limb is divided into
ninety degrees for navigation, and the whole limb into one hundred and eighty
degrees for surveying of land and astronomical uses, and figured at every
fifth degree. The letter E shews an index on the limb of the quadrant, the
letter a dial plate divided into minutes, and the letter G a dial plato divided
into seconds; and while the index E moves one degree on the limb, the index
on the dial F moves once round the said dial, and shews the sixtieth part of a
degree, and the index on the dial ( moves once round to every of those six-
tieth parts, by which means a degree of altitude is divided into three thousand
six hundred equal parts. But the dial F' being sufficient for coñion use, the other
will be made only for the curious. The Figure Number Two shews a person
taking observations on the water, and the figure I, K, is an index with Nonin's
division, and open sights at each end L, the center of which being put to C, the
center of the instrument, and then put upon a three-legged staff, as shewn by
the Figure Number One, it supplies the want of the theodolite, plane table, and
circumferenter, in surveying of land. M shews a needle that is to be used
with the said index I, K. The letter II shews a tricker, upon which every
observator is to keep a finger, and upon discovering the object sought after
must pull it in the same manner as at the firing of a gun, and immediately the
indexes cease to move and show the elevation and distance of the object sought
after to the sixtieth part of a degree. The letter P shews a little brass ball,
which, being gently pusht up with the thumb, the indexes move again for making
another observation. The letter N shews a square for putting on a key, by
which the seconds may be taken off and on, and consequently may be used or
not as the observator pleases, and with this instrument may be used telescopal
sights instead of open sights, as appears by the Figure Number Three; and the
letter O shews the place on which the key is put to lock up the work. And
this instrument is made of brass, copper, iron, or steel, or a compound mettal
properly prepared, and the inside of it consists of wheels and pinions, and is
moved by a weight acting from the principle or law of gravity only; and some
things in which this instrument excells all other yet invented are,-
That it requires no shade from the sun, nor any visible horizon, and an

page_text: observation may be taken with it in the night from the moon or fixed starrs,
and the latitude of the place be thereby known.
That the sight of one object is sufficient to make an observation by the
instrument, when by all other there must be two objects in view at one and
the same time; besides, there are no sliding pieces to move with the finger
on this instrument, which while an observator by other instruments is doing,
the opportunity of taking the observation is many times lost.
And, lastly, it divides a degree into sixty equal parts, whereby the altitude
of any heavenly body is shewn to a minute, and consequently the latitude of
the place to a mile at sea. All which is a true and full description of my
said Invention.
In witness whereof, I, the said John Barston, have hereunto sett my hand
and seal, this Thirteenth day of February, in the year of our Lord
One thousand seven hundred and thirty-eight.