IMPROVE- MENTS IN GRINDSTONES
Year: 1856

page_text: LETTERS PATENT to Richard Archibald Brooman, of 166, Fleet Street,
in the City of London, Patent Agent, for the Invention of "IMPROVE-
MENTS IN GRINDSTONES."-A communication from B. Picard, of Fontenay
le Chateau.
Sealed the 14th January 1857, and dated the 24th July 1856.
PROVISIONAL SPECIFICATION left by the said Richard Archibald Brooman
at the Office of the Commissioners of Patents, with his Petition, on
the 24th July 1856.
I, RICHARD ARCHIBALD BROOMAN, of 166, Fleet Street, in the City of
London, Patent Agent, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN GRINDSTONES," (communicated to me by B. Picard, of
Fontenay le Chateau, a foreigner residing abroad,) to be as follows:-
This Invention consists in constructing the outer edge or rim or grinding
surface of grindstones of a number of separate segniental blocks, held in
place by metal clamps, flanges, or bands. The clamps or flanges are cast in a
piece with or fixed by bolts, screws, or otherwise, to a web or framework, con-
sisting of a ring, connected by radial arms to a central boss; or one part of
the clamp may be cast with the ring, and the other part of the clamp may be
fixed to the first part by bolts, screws, or otherwise. The segmental blocks
may be dovetailed, to prevent them from being ejected from their seats or

page_text: proper positions by centrifugal force. The blocks are so tapered or formed as
to fit closely together, and when fixed in place their outer surfaces present a
compact and solid edge.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Richard Archibald Brooman in the Great Seal Patent Office
on the 24th January 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, RICHARD
ARCHIBALD BROOMAN, of 166, Fleet Street, in the City of London, Patent
Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of July, in the year of our Lord
One thousand eight hundred and fifty-six, in the twentieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Richard Archibald Brooman, Her special licence that I,. the said Richard
Archibald Brooman, my executors, administrators, and assigns, or such others
the said Richard Archibald Brooman, my executors, administrators, and
gns, should at any time agree with, and no others, from time to time
and at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United Kingdom
of Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN GRINDSTONES," a communication from B.
Picard, of Fontenay le Chateau, a foreigner residing abroad, upon the con-
dition (amongst others) that I, the said Richard Archibald Brooman, my
executors or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and ascertain
the nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Richard Archibald Brooman, do hereby
declare the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement thereof, reference being had to the Drawings annexed (that is to
say):
This Invention consists in constructing the outer edge, rim, or grinding
surface of grindstones of a number of separate segmental blocks, held in place

page_text: by metal clamps, flanges, or bands. The clamps or flanges are cast in a piece
with or fixed by bolts, screws, or otherwise, to a web or framework, consisting
of a ring connected by radial arms to a central boss; or one part of the clamp
may be cast with the ring, and the other part of the clamp may be fixed.
to the first part by bolts, screws, or otherwise. The segmental blocks may
be dovetailed, to prevent them from being ejected from their seats or proper
positions by centrifugal force. The blocks are so tapered or shaped as to fit
closely together, and when fixed in place their outer surfaces present a com-
pact or solid edge.
The Drawings annexed illustrate the manner in which the Invention is
carried into effect.
Figure 1 is a side view of a grindstone constructed according to this Inven-
tion; Figure 2, a plan; Figure 2*, section through the line 1, 2, of Figure 1.
a, a, are the segmental blocks, forming the outer edge of the grindstone;
b, b, metal clamps or bands for holding them in place, and made of proper
proportional size to resist the pressure exerted on their inner surfaces. The
dimensions of the surface and the degree of taper or slope of the dovetail are
regulated in such manner as to prevent splintering or splitting. The central
boss, radial arms, and shaft are also calculated accordingly. The blocks are so
formed that they may be put into place. by dropping them into the frame, and
pushing them forward from the centre towards the periphery.
Figures 3 and 4 shew a modification, in which the blocks are of the shape
shewn, and the frame is made in two parts, each portion is slipped over the
shaft, the blocks set in place, and the two portions of the frame brought
together and firmly secured by bolts c, c, or by screws or other equivalent con-
trivance, the bolts, &c. being of sufficient size to resist the tendency to separate.
The same frame will serve for grindstones or grinding surfaces of different
thicknesses. Figure 4* is a section through the line 1, 2, of Figure 3.
Figures 5 and 6 shew a grindstone formed of a number of segmental
blocks held in place by an external web or frame d, and having other and
smaller bands or webs e, e, which may be removed as the grindstone becomes
worn away. Each block projects such a distance from the metal frame that
articles may be ground on both sides of it, and on the edges f,f, two workmen
may grind on the same stone. Figure 6* is a section, through the line 1, 2, of
Figure 5.
The drawing action exerted on the radial arms is neutralized and thrown
wholly or partially on the frame, by giving to the action of the tenon 4 the
form of a trapezium instead of a rectangle.
By means of this Invention larger grindstones may be made than has

page_text: hitherto been done, on account of the difficulty of finding large masses of stone
of suitable character, and the danger of the stone flying under centrifugal
action. Moreover, the resistance of the metal is substituted for that of the
stone at the part where the greatest strain is exerted. A grindstone may be
repaired by merely replacing the outer periphery instead of having to replace
the entire stone. The stone may be ground on edgewise or sidewise.
And having now described the nature of the said Invention, and in what
manner the same is to be performed, I.declare that I claim,-
First, constructing the outer edge, rim, or grinding surface of grindstones of
separate segmental blocks, shaped to fit closely, and held in place. by bands,
clamps, or flanges, cast with or affixed to a web or framework; all as herein-
before described with reference to the Drawings annexed.
Second, the particular mode of constructing grindstones and mounting
the same, herein-before described, and represented in the Drawings annexed.
And, third, the methods of mounting the grinding surfaces of grindstones,
herein-before described.
In witness whereof, I, the said Richard Archibald Brooman, have here-
unto set my hand and seal, this Twenty-third day of January, One
thousand eight hundred and fifty-seven.
זגן n A dir .
R. A. BROOMAN. L.B.)