IMPROVEMENTS IN MACHINERY OR APPARATUS FOR GRINDING GRAIN
Year: 1856

page_text: LETTERS PATENT to William Frederick Bush, of the City and County of
Bristol, Millwright, and William Hewitt, of the same Place, Gentleman,
for the Invention of "IMPROVEMENTS IN MACHINERY OR APPARATUS FOR
GRINDING GRAIN."
Sealed the 24th February 1857, and dated the 26th August 1856.
PROVISIONAL SPECIFICATION left by the said William Frederick Bush
and William Hewitt at the Office of the Commissioners of Patents, with
their Petition, on the 26th August 1856.
We, WILLIAM FREDERICK BUSH, and WILLIAM HEWITT, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN MACHINERY OR APPARATUS
FOR GRINDING GRAIN," to be as follows:-
We propose to substitute for the present mill-stone a compound of ground
flint and clay, or similar suitable material, in which, when in a soft state, are
interspersed seeds and grain or other suitable substance (as currants would
be mixed in a pudding); the compound is then passed or pressed into moulds,
which when removed leave "burs" (as in brick making), which are slowly
dried previous to burning in a kiln, after which they are cemented together,
and form a porous mill-stone. The porousness may also be obtained by
perforating the compound in its soft state with wire; but we consider that
object to be more perfectly attained by the interspersement of seed, grain, or
other suitable perishable or fusable substance, as above described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Frederick Bush and William Hewitt in the Great
Seal Patent Office on the 25th February 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, WILLIAM
FREDERICK BUSH, of the City and County of Bristol, Millwright, and WILLIAM
HEWITT, of the same Place, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of August, 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 us, the said
William Frederick Bush and William Hewitt, Her special license that we,
the said William Frederick Bush and William Hewitt, our executors,
administrators, and assigns, or such others as we, the said William Frederick
Bush and William Hewitt, 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 "IMPROVE-
MENTS IN MACHINERY OR APPARATUS FOR GRINDING GRAIN," upon the condition
(amongst others) that we, the said William Frederick Bush and William
Hewitt, 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 immediately after the date of the said
Letters Patent.
NOW KNOW YE, that we, the said William Frederick Bush and William
Hewitt, 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):—.
In lieu of French "burrs," or those produced in any other country, also
instead of any material at present in use in the fabrication or making of those
grinding apparatus known as mill-stones, we use a composition hereafter
described. But before we enter into the detail of our Invention we will
explain its object. It is well known that the stones formed of "burrs" are
defective (whether French or other), and lose by use (in more or less time
according to the quality of the burrs composing them) their cutting or grinding
surface, and to renew such surface the stone must be removed and tooled; or,
in other words, time and power are lost in consequence of the stones glazing

page_text: or getting smooth. In mill-stones for grinding grain formed or composed
according to our Invention no such inconvenience arises, the stone, once fitted,
usually remaining till nearly worn away, and doing its work without the
cutting or grinding face being lost by wear (being of a regular texture, and
technically termed "full of life.")
To prepare our mill-stones we reduce into powder flint and other substances,
(hereafter described and detailed) and having so done, we mix therewith
seeds or grain of any kind, stirring the whole (by any convenient process) till
the mass forms a paste, and the grain or seed be uniformly (or as nearly so as
possible) distributed throughout it. Hitherto we have found hemp seed to
be the substance most fitted for our purpose, the size of the grain being
suitable, and its oleaginous nature assisting the after process of firing the
"burrs." We say we reduce the flint and other substances to powder, and
we find such process to answer well, but in some cases we use the flint in its
natural state, in combination with the composition formed by the other
substances. We are also aware that the porousness produced by the seeds
(when they have been discharged by heat, and have left cavities in their.
place) may be produced in some degree by perforating our composition with
wire (while in its soft state), or placing piped, or tubular, or other substances
of a perishable nature (capable of producing cavities therein) and discharging
them by heat as we do the seed; and we have tried some of these methods,
but find the grains or seed before mentioned to answer our purpose much
better, producing cutting or grinding surfaces of a superior nature. In
making our composition burrs, we take of flint two hundredweight and a
half, Cornish stone two hundredweight, China clay three hundredweight
and a half, felspar one hundredweight, Irish flint one hundredweight, and
of common clay, five hundredweight, the whole being previously ground
seperately. We mix these powders well together with water, and work them
in a mill, or by any other means that will effect a thorough mixing, adding
thereto at intervals a quantity (greater or less according to the closeness or
otherwise of the stone to be made) of hemp seed (or other seed or grain), to
insure a sufficiency of small cavities being left in the "burrs" when the seed
shall have been discharged, in a manner honeycombing the mass. When the
mixing is complete we pass and press the composition into moulds (as in
brick making); on removing these moulds the composition will have been
formed into "burrs," and these must be allowed to dry; when sufficiently
dried the burrs are placed in a kiln and burnt; this operation discharges the
hemp seed, (being materially assisted by the oleaginous nature of the seed, as
aforesaid,) Icaving cavaties in lieu thereof, and the burnt or kilned composition

page_text: is then found to be sufficiently firm or hard to be used for grinding grain or
other substances, the cavaties aforesaid forming (as they are worn by use)
cutting edges, grinding the grain in a very superior manner, and rarely requiring
to be tooled, dressed, or otherwise operated upon.
In making use of the natural flint in combination with the composition
aforesaid, we construct the top and bed stone (of mills) with a cap made of
iron, and also a rim of the same metal; round within this rim we form the
stone, composing it of layers upon layers of flint, grouted or cemented together
by pouring in our before-described composition or cement, thus uniting the
flints firmly together, the whole being retained in solid by the cap and rim
before mentioned.
Having now described the nature of our Invention of stones for grinding
grain and other substances, and the manner in which we carry it into practical
effect, we desire it to be distinctly understood that we do not confine ourselves
to the exact proportions of the substances herein-before mentioned in making
or compounding our composition or cement for mill-stones, nor to the quantity
or description of seed or grain we employ in such mixing to form the cavaties
in the "burrs" (after kiln burning), as such may be varied to suit particular
cases; or from the better or inferior nature of the articles of which the cement
or composition for grinding grain or other substances is composed; nor do
we lay any claim to the exclusive use of any of the substances or articles
herein named, taken or considered seperately, and not used in combination
for the purposes of our Invention which we declare to be, and we claim,-
Firstly, the exclusive use of the paste, composition, mixing, or cement
made, composed, or fabricated in the manner and for the purposes herein-
before set forth and described.
Secondly, the exclusive use of mill-stones formed by a compound of natural
flint, combined with the composition aforesaid, in the mode or manner herein-
before described.
In witness whereof, we, the said William Frederick Bush and William
Hewitt, have hereunto set our hands and seals, this Fourteenth day
of February, in the year of our Lord One thousand eight hundred and
fifty-covon
WILLIAM FREDERICK BUSH. (L.S.)
Witness,
WILLIAM
HEWITT.
(L.S.)
SAMUEL BULL, of Bristol.