IMPROVEMENTS IN CONSTRUCTING AND MOUNTING OR HANGING MILLSTONES
Year: 1865

page_text: PROVISIONAL SPECIFICATION left by William Henry Parker at the
Offee' of the Commissioners of Patents, with his Petition, on the 18th
October 1865:
I, WILLIAM HENRY PARKER, of Kilmacow, in the County of Kilkenny,
Ireland, Miller, do hereby declare the nature of the said Invention for
IMPROVEMENTS IN CONSTRUCTING AND MOUNTING OR HANGING MILLSTONES," to
be as follow:
Millstones as at present constructed consist of a mass of "French burry
fitted together in a circular form and bound tightly round the circumference
with iron hoops or bands, the joints between the said burr stones being filled
in with plaister of Paris, or other similar cement. The 'stones' thus constructed
not being sufficiently heavy in themselves additional weight is given to thei
by a backing of plaister, cement, and broken' stones mixed together, and this
backing, being. plaistered smooth, and confined round the circumference with
an iron band, gives thickness, weight, and substance to the stone'; búť'agréať
difficulty has always been experienced in balancing stones of this construction
owing principally to the fact that the specific gravity of this conglomerate backing
varies throughout its entire mass, and hence, however truly the stone may be
balanced when at rest, as soon as it commences to revolve rapidly this
equilibrium is destroyed or counteracted by the action of centrifugal force and
+

page_text: the stone commences to run untruly or to "dip" as it is termed. This
"dipping" of the stone is also increased by a defective method of mounting
or hanging the same, a great proportion of the weight being placed above the
point of suspension instead of below it. In order to remedy these defects I
propose to construct and mount or bang the upper or running millstones as
follows:-Instead of the ordinary backing as above described, I employ a solid
cover of cast-iron or other metal in the form of a broad annular plate
having a rim or band round and at right angles to its outer periphery, and
also a similar rim or band round its inner circumference or eye, so that this
backing (when inverted) forms an annular box into which I place the "burrs"
previously cut to the required form and size and fitted neatly together. I
then proceed to fuse the whole together into one solid mass by running molten
metal or cement into the joints, or after building a stone in the ordinary
manner I reduce it to an uniform thickness, and then fix or fit it into the
iron cover or backing with molten metal or cement as above described. The
"burrs" being thus embedded tightly into their metal backing I then shrink
iron hoops (in the usual manner) round that part of the stone which projects
beyond the metal bands. When a millstone of this construction wears away
and thus becomes lighter, additional weight can be given to it at any time by
bolting cast-iron annular plates on to the top of the metal backing. In.
casting the iron backing (and also the annular plates) I leave any required
number of holes or openings in the top to receive shot or weights for adjusting
the equilibrium of the stone. The hanging apparatus which I propose to
employ consists chiefly of a hanging iron consisting of a central boss having
three, four, or other convenient number of arms, the outer ends of which are
let into or otherwise affixed to the inner band or eye of the cover near to its
upper edge, so as to place the centre of suspension as high as convenient;
through the centre of the boss passes a bolt terminating at its lower extremity
in a ball, the said ball resting in a cup or socket formed in the upper end of
the driving spindle. Upon the upper end of the driving spindle below. the
cup or socket is keyed a clutch, having arms projecting upwards between the
arms of the hanging iron, so that the stone is thus compelled to revolve with
the driving spindle at the same time that owing to the action of the ball-and-
socket joint, the axis of the stone may vary in any required direction from
that of the driving spindle so as to preserve the true balance of the former.
In order to keep the grain constantly fed into the working space between the
upper and lower stones I propose to place in the eye of the former a "sweeper
composed of a central boss (with four (or other convenient number of) armis,
"

page_text: curved outwards so that as the upper stone revolves the grain is swept
outwards by the arms.
In constructing the lower or fixed millstones I propose to make them also
with a metal backing as above described, and to furnish the lower edge with a
flange or rim all round, by means of which it may be bolted securely to its
bed or floor.