A CERTAIN MODE OR MANNER OF MAKING, UNITING, AND APPLYING CAST IRON BLOCKS, TO BE SUBSTITUTED IN LIEU OF KEYSTONES IN THE CONSTRUCTION OF ARCHES, THE SAID CAST IRON BLOCKS BEING KEPT IN THEIR PROPER POSITION, AND MADE TO ABUT AGAINST EACH OTHER, AND TO SUPPORT ANY INCUMBENT STRUCTURE, BY MEANS OF WROUGHT IRON BARS, AND WROUGHT OR CAST IRON BRACES, BEING AFFIXED TO THEIR SIDES, AND PASSING HORIZONTALLY BETWEEN RIBS COMPOSED OF THE SAID CAST IRON BLOCKS
Year: 1795

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROWLAND
BURDON, late of Harley Street, Cavendish Square, in the County of Middlesex,
now of Castle Eden, in the County of Durham, Esquire, 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
at Westminster, the Eighteenth day of September, in the thirty-fifth year of
His reign, give and grant unto me, the said Rowland Burdon, my executors,
administrators, and assigns, His special licence that I, the said Rowland
Burdon, my executors, administrators, and assigns, during the term of years
therein mentioned, should and lawfully might make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, my Invention
of "A CERTAIN MODE OR MANNER OF MAKING, UNITING, AND APPLYING CAST IRON
BLOCKS, TO BE SUBSTITUTED IN LIEU OF KEYSTONES IN THE CONSTRUCTION OF ARCHES,
THE SAID CAST IRON BLOCKS BEING KEPT IN THEIR PROPER POSITION, AND MADE TO
ABUT AGAINST EACH OTHER, AND TO SUPPORT ANY INCUMBENT STRUCTURE, BY MEANS
OF WROUGHT IRON BARS, AND WROUGHT OR CAST IRON BRACES, BEING AFFIXED TO
THEIR SIDES, AND PASSING HORIZONTALLY BETWEEN RIBS COMPOSED OF THE SAID CAST
IRON BLOCKS;" in which said Letters Patent there is contained a proviso
obliging me, the said Rowland Burdon, by an instrument in writing under
iny hand and seal, to cause a particular description of the nature of my said.

page_text: Invention, and in what manner 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 complianco with the said proviso, I, the said
Rowland Burdon, do hereby declare that my Invention consists in applying
iron or other metallic compositions to the purpose of constructing arches, upon
the same principle as stone is now employed, by a subdivision into blocks casily
portable, answering to the keystones of a common arch, which being brought
to bear on each other, gives them all the firmness of the solid stone arch.
whilst by the great vacuities in the blocks and their respective distances in
their lateral position, the arch becomes infinitely lighter than that of stone,
and, by the tenacity of the metal, the parts are so intimately connected that
the accurate calculation of the extrados and intrados, so necessary in stone
arches of magnitude, is rendered of much less consequence.
Fig. 1 (as below) represents a block of cast iron five feet in depth from A
to A, and four inches in thickness, having three arms B, B, B, and making a
part of a circle or ellipsis. The middle arm is two feet in length from B to
C, and the other two arc in proportion. On each side of the arms are grooves
(three quarters of an inch deep and three inches broad), for the purpose of
receiving malleable or bar iron, and in cach arm are two bolt holes.
D (Fig. 2) represents two of these blocks placed together, and the joints
confined to their respective positions by the bar iron on each side of the
arms, as .nt E, E, E, which, with other similar blocks so united and bearing
upon each other, become a rib.
Fig. 3, and F, F (Fig. 2), are hollow tubes, six feet long and four inches
in diameter, having shoulders at each end, with holes answering to those of
the blocks. G is a block of another rib, connected with the former by the
tubes F, F, placed horizontally. Through the holes in the shoulders and
arins of the block and bar iron are bolts (fastened with cotterels or forclocks),
as at H, H, H, H. The blocks being united with each other in ribs, and the
ribs connected and supported laterally by the tubes, as above described, the
whole becomes one mass, having the property of keystones cramped together.
The blocks and tubes above specified are those intended to be used in the
construction of the arch of the bridge now erecting by me across the Rivers
Wear at Wearmouth, near Sunderland, in the County of Durham. The arch
is a segment of a circle, whose chord or span is two hundred and thirty-six
feet, its versed zine or height thirty-four feet, and its breadth thirty-two feet,
consisting of six ribs. But the sizes of the blocks. tubes, and other parts, with

page_text: ROWLAND BURDON. (L.S.)
AND BE IT REMEMBERED, that on the same Seventh day of October,
in the year above written, the aforesaid Rowland Burdon came before our
Lord the King in His Chancery, and acknowledged the Specification afore-
O said, and all and every thing therein contained, in form above written.
And also the Specification aforesaid was stamped according to the to the
tenor of the Statute in that case made and provided.