A NEW AND IMPROVED METHOD OF MAKING MAGNETICAL OR SEA COMPASSES, COMMONLY CALLED AZIMUTH, AMPLITUDE, STEERING, AND HANGING COMPASSES, FOR THE IMPROVEMENT AND BENEFIT OF NAVI- GATION, MARINE SURVEYING, AND SO FORTH
Year: 1791

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GABRIEL
WRIGHT, of the Parish of Saint Mary, Islington, in the County of Middle-
sex, Optician, send greeting.
WHEREAS His most Excellent Majesty King George the Third did,
by His Letters Patent under the Great Seal of Great Britain, bearing date
the Fifth day of July, in the thirty-first year of His reign, give and grant
unto me, the said Gabriel Wright, His special licence that I, the said
Gabriel Wright, during the term of years therein expressed, should and law-
fully might make, use, exercise, and vend, within England, Wales, and Town
of Berwick-upon-Tweed, my Invention of "A NEW AND IMPROVED METHOD OF
MAKING MAGNETICAL OR SEA COMPASSES, COMMONLY CALLED AZIMUTH, AMPLITUDE,
STEERING, AND HANGING COMPASSES, FOR THE IMPROVEMENT AND BENEFIT OF NAVI-
GATION, MARINE SURVEYING, AND SO FORTH;" in which said Letters Patent there is
contained a provisoe obliging me, the said Gabriel Wright, under my hand and
seal, to cause a particular description of the nature of my said Invention, and
how the same is to be performed, to be inrolled in His Majesty's High Court
of Chancery within one calendar month after the date of the said recited
Letters Patent, as in and by the same (relation being thereunto had) may
more fully and at large appear.
NOW KNOW YE, that in compliance of the said provisoe, I, the said
Gabriel Wright, do hereby declare that my said Invention of A New and
Improved Method of Making Magnetical or Sea Compasses, commonly called

page_text: Azimuth, Amplitude, Steering, and Hanging Compasses, for the Improvement
and Benefit of Navigation and Marine Surveying, and so forth, is described in
the Plan thereof hereunto annexed.
In witness whereof, I, the said Gabriel Wright, have hereunto set my
hand and seal, this Second day of August, One thousand seven hundred

page_text: The Description of a
La new Invention & Construction of the Azimuth Amplitude Steering & Hanging Compasses for the improve..
nent of Navigation Murine Surveying go by Gabriel Wright Optician of St Mary's Islington,
I in the County of Middlesex...
Thi's Lutent Compass is hung by two Metal Kings called Gimbel in a Hood or Metal box, the inside Compass box or kettle is also
made of Wood or any kind of Metal (Iron excepted). On the Cylindrical part of the kettle on the outside & near the centre of motion as
fastend a
a ring of Lead, or other Metal of a proper weight to Balance the Compass Box & keep it horizontal when in use & to prevent
it's getting into a pendulous or vibrating Motion - On the centre of the bottom on the inside of the kettle is fix't a metal Pedestal fastend
• a Nutt & Screw on the Top of this Pedestal the different Pillars or points (described by the Copper Plate Figures below) are screw'd
n & off at pleasure, being all at different times made use. of to
or suspend the Magnetic Needle & Cards with & without the
by
Carry
hollow Metal Cone - The different parts of the Gimbel Compass. Fig 1th are the following viz: –
Fig 1. The Section of the Compass
The Wooden Box in which the Compass ishing ..
The Sliding Lid
The Metal Compass Box or Kettle with a um & Glass Cover.
A king of Lead made fast to the Hettle._
Two Brass Nutts to fasten the shoulders that support the Gimbele...-
The Brass Kings or Gimbels
A Brass Pedestal fasted by
a Nutt to the bottom of the Kettle with a Screw on the Top at II. to receive the different pillars or lenkes
that are made use of in this Compass viz Fig 2. 3. & 4 . —
A small Pillar made of Metal or some other substance with a round top on which the Cone B is suspended.___
A Cone made of Metal or any other substance with a fine sheet or Aletal Point on the top of which the Magnetic Needle & Cord Hay
The Magnetic Needle & Card....
be used.
The Agat Cap which drops into a Cylindric Brass Box & is kept in by a Jical Spring screv'd upon it - This Agat Cap is con-
cowo & polished at both ends, therefore shou'd one-end be found to wear which it undoubtedly will in time the other may
The Brass Box which contains the agat & Spiral Spring Screwv'd into the Centre of the Needle & suspended on the Seel point of
the Cone K. for use._
Fig: 6. A Compass Needle with an inverted Steel or Brass Point made use of with the Gumbel Centre on a Brass Pillar Fig 4
This point goes through
a Brass Cap, with a Spiral Spring inside, and having a round Plate fastend to it, will give way.
the Spring & prevents the Point from wearing the Agat bap on which it moves, there is a small screw O. on the top to adjust
the Point.
callid
with
The Compass Cards & Needle as before described are made use. of in the Azimuth Amplitude Steering & Hanging Compasses, also to
the tonical Compass with the new invented Semicircle to prevent its turning round horizontally on its centre or Prop. See Fig 5.
On the Card of the Azimuth Compass are a number of Lines drawn quite across from the divisions on one side to those opposite.
Azimuth Cards
Rurallel to those usually drawn through the centre of the Compass Card when divided in Four Quarters as in common.
to the breadth of from half an Inch to three inches according to the size of the Cand. There is also a Metal Circle Semicircle or Quadrant with
commonly
a nonius) division to
an horizontal Oladade or Index moving from the centre having a Vernier (or as it is more
divide the Degrees
on the Arch of the Circle Semicircle or Quadrant into parts of a degree call'd minutes. There is also one or hvo
oblique or overtical position to
Sight Vanes or Indexes with a joint affix'd to the Sorizontal Index before described to lift up into an
shoir the Suns Shadow by a Spot from a Glass Lens a Small hole or vertical line, as may be most convenient. On the plun
of the Circle Semicircle or Quadrant is placed one or two metal frames which contain reflecting plain Mirrors adpisted to an
n horijontal position by the Marine Horizon with
Angle to shew the Horizon of the Line by which means the Compass is kept in an
out depending entirely
ung
or cover
on its being truly balanced, the Metul Circle Semicircle or Quadrant may either be made fast to the bras
of the Compass, or made use of detached howing a handle to faster to it for the last mentioned purpose...