DRESSING OR CUTTING MILLSTONES
Year: 1870

page_text: PROVISIONAL SPECIFICATION left by Edward Copeland Stiles and
John Fenn Elsdon at the Office of the Commissioners of Patents,
with their Petition, on the 4th July 1870.
We, EDWARD COPELAND STILES, of 30, Grafton Street, Fitzroy Square,
in the County of Middlesex, Gentleman, and John FENN ELSDON, of
No. 43, Great Coram Street, Brunswick Square, in the aforesaid County,
Gentleman, do hereby declare the nature of the said Invention for
"DRESSING OR CUTTING MILLSTONES," to be as follows:-
Take the two millstones which it is intended to operate upon and
grind their faces quite smooth and even, the object being to make each
of these faces what in geometry is termed a plane; these faces are then
divided into equal parts by straight lines drawn from the circumference
through the eye to the other side; the number of these parts vary accord-
ing to the size of the stone, those of 30 inches require but eight parts,
those of 6 feet will need sixteen. We then make a curved rule as repre-
sented in the Drawing by which the shape of the dress upon the face
of the stone is laid off or measured; the concave side of the rule must.
in every case have exactly the same curvature as the circumference of
the stone which is to receive the dress, or, in other words, the millstone.

page_text: and the curve of both sides of the rule or model must have an equal
radius. This rule is made just long enough to reach from the cir-
cumference to the eye of the stone in measuring it. The rule must
be used with the broad end towards the circumference, and the narrow
end towards the eye of the stone. The rule is made from an eighth to
a quarter of an inch broader at one end than at the other; both sides
of the rule must have the same curvature, the broadest end of these
rules vary from one inch to two and a quarter inches in width; their
size is large or small in proportion to the diameter of the stone to be
dressed. A section of the bottom of the furrow along its whole length
is also a curve whose radius is equal to that of the circumference of the
stone. The principal or master furrows are laid off thus:-Lay the
point A of the rule upon the point A at the eye of the stone, and the
point B of the rule upon B at the circumference, then mark off its size
and shape upon the face of the stone. This is to be the size and shape
of the master furrow, this furrow is made from one quarter of an inch
to an inch in depth at the eye and slightly deepening as it approaches
the circumference. The furrow is cut nearly perpendicular on the
convex side, but not quite, and is brought to a feather edge on the
concave side so as to give the bottom of the furrow the same curvature
as the circumference of the stone. A similar furrow is to be made on
each of the straight lines which divide the surface of the stone into
equal parts, a small portion of cach of these furrows is cut out or
deepened at the eye in order that they may receive the grain more freely.
After all the master furrows are made place the concave side of the rule
on the convex line of the master furrow, and mark off its size upon the
stone, then place the concave side of the rule upon the line which was
last drawn and mark off its size again, when it will be found that the
end of this next to the eye will fall upon the master furrow. Upon
the size of the rule marked off last you must make a furrow similar in
shape to the master furrows, this is called the short furrow, and its end
next the eye will not be exactly like a master furrow, for it will there
intersect one of them. These two furrows with the two bands intervening
occupy all of one of the several equal parts into which the surface of the
stone has been divided and the remaining divisions are filled exactly in
the same manner. Upon the smooth surfaces of the size of the rule
which are now left between each master and short furrows, you must
cut small grooves from seven to twelve in number, corresponding to the
size of the rule; these grooves must be made from a sixteenth to an

page_text: eighth of an inch deep and have the same curve as the rule. Upon the
equal number of triangular surfaces you must cut one groove along the
line which is next to the master furrow so as to preserve that edge, then
cut another groove through the centre of the triangle so as to run from
its acute angle to the middle of its circumference. Then cut grooves
like those above on each of this and parallel with it until they cover the
whole of the angle; these grooves are easily and accurately laid off with
the rule.
The annexed Drawing and description is supposed to be the bed or
bottom stone of the mill; the upper stone or runner is dressed precisely
in the same manner, but it is easily understood that when this top stone
is inverted and placed upon the lower one the curvature of its lines will
be reversed. When the mill is in motion the convex curves of the upper
stone or runner are in front. It will be scen that about one-half of cach
master furrow next the eye is behind the diameter upon which it is
made, while the reverse of this is truo in relation to the other half
situated next the circumference. It will be also seen that the short
furrow has double the draft or inclination of the master furrow. The
construction of these furrows and grooves is such as to retain nearly
all the grain to the eye or centre of the stone.
What we desire to secure by Letters Patent is the improved method
of dressing millstones, which we have described above as fully and
accurately as we can.