a instrument called
Year: 1779

page_text: TO ALL TO WHOM THESE PRESENTS SHALL. COME,
greeting.
WHEREAS His most Excellent Majesty has, by Letters Patent, bear-
ing date at Westminster, the Seventh day of September, in the year of
our Lord Oue thousand seven hundred and seventy-nine,' granted unto
me, Christopher Berger, of the Parish of Saint Mary, Lambeth, in the
'County of Surrey, Engine Maker, my executors, admors, and assigns,
the sole use and benefit and advantage of my new Invention of a
certain instrument called "A SPIRAL WEDGE, FOR THE PURPOSE OF
ELEVATING, POINTING, AND LOWERING OF CANNON AND ALL OTHER PIECES
OF ORDNANCE USED BOTH BY SEA OR LAND, AND THAT WITH GREATER EASE,
EXPEDITION, AND EXACTNESS THAN THE METHOD NOW USED," provided that
I did, within four calendar months from the date of the said Letters
Patent, cause a particular description of the nature of my said
Invention, and in what manner the same is to be performed, by writing
under my hand and seal, to be inrolled in the High Court of Chancery,
otherwise the said Letters Patent to be void.
NOW KNOW YE, that I, the said Christopher Berger, in com-
pliance with the proviso in my said Patent mentioned, do hereby

page_text: describe and ascertain the nature of my said Invention, and declare
that the same is composed of wood and iron, or any other material
that will take and retain the form of a cylindrical or poligonical spiral
wedge, turning round on a vertical axis, and is made to affix on or
shift occasionally to all gun carriages already made or hereafter to be
made, the base of which said spiral wedge stands horizontally on the
axletree or stool bed, or any part of a carriage which may receive the
same, so that the breach or base ring of the cannon or ordnance, or
any part of the same acting on the spiral form of the said spiral wedge,
which serves for the purpose of elevating or depressing the said cannon
or ordnance, and acts by a horizontal or other lever or levers round its
vertical axis, as the case may require, Drawings of which I have
annexed to this Specification, with references.
In witness whereof, I have hereunto affixed my hand and seal,
this Fifth day of January, in the year of our Lord One
thousand seven hundred and eighty, and in the twentieth year
of His Majesty's reign.

page_text: REFERENCE TO THE DRAWINGS.
be
any
Several forms of the Spiral Wedge the exterior or circumscribing outlines
may
other figure not being confined to circular, and composed of any material, the Inventor
may think proper:
The vertical axis keyed or shewed on the axle-tree, or may be fastened or keyed on the bet-
tom of the Spiral Wedge and to work through the parts belonging to the axle tree
of the Carriage.
The Leaver or Handle which shifts and is made to fit at either end, the holes round
the side of the Spiral Wedge to force its revolution.
Plan of a Carriage with Spiral Wedge fixed thereon.
End View of the elevation thereof."
Apiece added to the axle tree of the Carriage, for the Base Ring of the Spiral Wedge
to traverse on, with a scale of degrees marked thereon to shew the elevation, and depres-
-sion of the Gun.
Side View of the same with a Gun mounted.
Stop of the Spiral Wedge to prevent its turning too far or depressing too much, as the
case may require.