IMPROVEMENTS IN APPARATUS FOR DRESSING MILLSTONES
Year: 1868

page_text: LETTERS PATENT to Bryan Corcoran and William Dunham, of Mark
Lane, in the City of London, for the Invention of "IMPROVEMENTS IN
APPARATUS FOR DRESSING MILLSTONES."
Sealed the 26th February 1869, and dated the 28th August 1868.
PROVISIONAL SPECIFICATION left by the said Bryan Corcoran and
William Dunham at the Office of the Commissioners of Patents,
with their Petition, on the 28th August 1868.
We, BRYAN CORCORAN and WILLIAM DUNHAM, of Mark Lane, in
the City of London, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN APPARATUS FOR DRESSING MILLSTONES," to be as
follows:-
This Invention relates to improvements upon an Invention for cutting
and dressing millstones, for which Letters Patent were granted to George
Davies, dated April 30th, 1867, No. 1245, and consists,-
Firstly. In fixing, by set screws or other suitable means, a vertical
shaft and boss in the eye of the millstone to be dressed; the said shaft

page_text: and boss supporting a horizontal arm or arms radiating from or near the
centre of the millstone to suit the required dress, and the said shaft and
boss and its radiating arm or arms being so constructed that they can
be regulated and adjusted in such manner that the diamond cutter shall
work in a true plane. The said radial arm or arms carry a diagonal
or other suitable rest, which is fitted with the diamond tool carriage, so
that the rectilinear and rotary motion of the diamond shall produce
parallel cracks or lines consecutively upon each "land" in one quarter
of the area of the millstone, the central shaft and boss being then
revolved, so that the remaining quarters may be operated upon in
succession.
And, secondly. We employ a similar apparatus to that above described,
but with the central shaft and boss and its radial arm or arms so
arranged that the diamond cutter will act concentrically to the work
performed, but excentrically with the millstone, so as to be specially
adapted to that kind of cut or crack known as the curved, circular, or
sickle dress, and in such manner as to produce perfectly curved cracks
or lines corresponding with the required dress of the stone, the said
curved cracks or lines having a perfect fore edge, a result never before
accomplished.
This part of our Invention can be worked in conjunction with or
indonandantly of the Dotont ahora mantioned
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Bryan Corcoran and William Dunham in the
Great Seal Patent Office on the 27th February 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, BRYAN
CORCORAN and WILLIAM DUNHAM, of Mark Lane, in the City of
London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of August, in the
year of our Lord One thousand eight hundred and sixty-eight, in
the thirty-second year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto us, the said Bryan Corcoran and
William Dunham, Her special licence that we, the said Bryan Corcoran

page_text: and William Dunham, our executors, administrators, and assigns, or
such others as we, the said Bryan Corcoran and William Dunham, our
executors, administrators, and assigns, 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 APPARATUS FOR DRESSING MILLSTONES," upon the condition (amongst
others) that we, the said Bryan Corcoran and William Dunham, our
executors or administrators, by an instrument in writing under our,
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 imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that we, the said Bryan Corcoran and William
Dunham, do hereby declare the nature of our said Invention, and in
what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement (that is to say):―
This Invention relates to improvements upon an Invention for
cutting and dressing millstones, for which Letters Patent were granted
to George Davies, dated April 30, 1867, No. 1215, and consists,―
Firstly. In fixing by set screws or other suitable means a vertical
shaft and boss in the eye of the millstone to be dressed; the said shaft
and boss supports a horizontal arm or arms radiating from or near the
centre of the millstone to suit the required dress; the said shaft and boss
and their radiating arm or arms being so constructed that they can be
regulated and adjusted in such manner that the diamond cutter shall
work in a true plane. The said radial arm or arms carry a diagonal or
other suitable rest, which is fitted with the diamond tool carriage, so
that the rectilinear and rotary motion of the diamond shall produce
parallel cracks or lines consecutively upon each "land" in one quarter
of the area of the millstone, the central shaft and boss being in some
cases revolved, in other cases the boss only being revolved, so that the
remaining quarters may be operated upon in succession.
And, secondly. We employ a similar apparatus to that above described,
but with the central shaft and boss and their radial arm or arms so

page_text: arranged that the diamond cutter will act concentrically to the work
performed, but eccentrically with the millstone, so as to be specially
adapted to that kind of cut or crack known as the curved, circular, or
sickle dress, and in such manner as to produce perfectly curved cracks
or lines corresponding with the required dress of the stone, the said
curved cracks or lines having a perfect fore edge, a result not hitherto
accomplished.
1.
This part of our Invention can be worked in conjunction with or
independently of the Patent above referred to.
In order that our Invention may be clearly understood we will proceed
to describe it with reference to the accompanying six Sheets of Drawings,
and to the figures and letters thereon.
On Sheets 1 and 2, a is the vertical shaft which is stationary or fixed
in its upper bearing and lower bearing c, adjusted vertically in both
bearings by set screws d, d. The boss e which revolves round the
shaft a carries on V slides f the horizontal arm g radiating from or near
the centre of the millstone to suit the required dress. The said
radiating arm g carries the sliding tool carriage i constructed in a similar
manner to the tool carriage described in the above-mentioned Patent,
No. 1245, 1867. Parallel cracks or lines are produced consecutively
upon cach "land" in one quarter of the millstone, without the necessity
of shifting the boss e, the arm g being traversed along the V slide fon
the said boss e by means of the wheel and screw shaft 1, and is traversed
along a V or other slide on the arm g in a rectilinear direction by the
slotted lever m actuated by the lever n, and engaging with the tool
carriage i until the whole of the "lands" or furrows in one quarter are
completely dressed; the said boss e and its arm g are then revolved
around the central shaft a and another quarter operated upon in a
similar manner. The riggers o, p, around which the cords q, r, run
revolve loose on the fixed shaft a, the cord passing over the pulleys 8, 8,
to the spindle carrying the revolving diamond cuttor t.
On Sheets 3 and 4 is represented a modification of our Invention. " is
the vertical shaft revolved from one quarter to the other, as required,
and in this case the boss v may be keyed on the shaft, and carries on V
slides the sliding frame and arm . At the upper part of the shaft u
is a second boss y also supplied with V slides a', on which works the
upper part 2 of the frame x, a stay being used to connect the two
frames together when required. Both the upper and lower sliding frames

page_text: are traversed by the hand wheel d² and screw shaft e, a band being
passed from the said shaft to a similar screw shaft for traversing
the upper boss. The tool carriage f* is worked along slides on the
arm in a similar manner to that above described, a suitable stop being
placed at the ends of the lands and furrows to prevent the tool from
crossing the cracks on the land of the next quarter. Or in some cases
we may dispense with the upper bearings of the vertical shafts, and in
licu thereof we place in the eye of the millstone a short vertical shaft of
conical or other shape, its sole bearing being fixed therein below the boss
by means of set screws or their equivalents, the said boss and its arm
revolving thereon in a similar manner to that above described.
On Sheets 5 and 6 we illustrate the second part of our Invention. a is
the vertical shaft supported in bearings b and c, and having the boss d
fixed thereon by set screws or otherwise, the said boss having projecting
therefrom a frame d', one part of which e is curved from a radius struck
from the outer end of the arm d', the said radius corresponding to the
radius of the curved cracks on the millstone. The end of the said
frame d serves as a fulcrum, on which turns the arm f, the said arm
working in slides on the under part of the arm of the frame e, so that
the diamond cutter g will act concentrically to the work performed, but
eccentrically with the millstone, whereby the kind of cut or crack
known as the curved, circular, or sickle dress is accurately performed,
and the said curved cracks or lines have a perfect fore edge, a result
never before accomplished. The outer ends of the said frame d' and e
may be stayed when desirable to the upper part of the shaft a by the
stays h, i, the cutter being traversed from land to land and furrow to
furrow in the tool holder along the slide on the arm by means of
the hand wheel m and screw n.
Having now described the nature and particulars of our said Invention,
we claim,
First. The vertical shaft a in conjunction with the angular arm or
arms g radiating from or near the centre of the millstone, whereby the
diamond cutter works in a true plane and rectilinear direction, no part
of the machine itself resting on the face of the stone, substantially as
shewn and described.
Second. In conjunction with the vertical shaft, radiating arm or arms,
and revolving diamond cutter, we claim the means for dressing the

page_text: whole of a quarter of a millstone without altering the position of the
boss, substantially as shewn and described.
Third. We claim the production of the circular or sickle dress by the
means and apparatus herein shewn and described.
In witness whereof, we, the said Bryan Corcoran and William
Dunham, have hereunto set our hands and scals, this Twenty-
fifth day of February, in the year of our Lord One thousand
eight hundred and sixty-nine.
BRYAN CORCORAN.
(L.S.)
WILLIAM DUNHAM. (L.S.)
BRYAN CORCORAN.
(L.S.)
WILLIAM DUNHAM. (L.S.)