CERTAIN IMPROVEMENTS IN MACHINERY FOR GRINDING GRAIN, PAINT, AND OTHER SUBSTANCES
Year: 1847

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
STIRLING NEWALL, of Gateshead, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Fourteenth day of
October, One thousand eight hundred and forty-seven, in the eleventh year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Robert Stirling Newall, my exors, admors, and assigns,
Her especial licence, full power, sole privilege and authority, that I, the
said Robert Stirling Newall, my exors, admors, and assigns, or such others
as I, the said Robert Stirling Newall, my exors, adñiors, or assigns, should at
any time agree with, and no others, from time to time and at all times during
the term of years therein expressed, should and lawfully might make, use,
exercise, and vend, within England, Wales, and the Town of Berwick-
upon-Tweed, and also in the Islands of Jersey, Guernsey, Alderney, Sark,
and Man, and in Her Colonies and Plantations abroad, my Invention of
"CERTAIN IMPROVEMENTS IN MACHINERY FOR GRINDING GRAIN, PAINT, AND OTHER
SUBSTANCES;" in which said Letters Patent is contained a proviso that I, the said
Robert Stirling Newall, shall cause a particular description of the nature of
my said Invention, and in what manner the same is to be performed, by an
instrument under my hand and seal, to be enrolled in Her Majesty's High

page_text: Court of Chancery within six calendar months next and immediately after
the date of the said in part recited Letters Patent, as in and by the same,
reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Robert Stirling Newall, do hereby declare the nature of my Invention of
Certain Improvements in Machinery for Grinding Grain, Paint, and other
Substances.
It is well known that "mill stones" are made of buhr stone, a form of silica
which is cellular in its structure, and that the best buhr stones for grinding
corn have about an equal proportion of solid matter and of vacant space.
During the process of grinding the vacancies soon get filled up with the
material which is being ground, and in this manner there are formed alternate
spaces of hard and soft matter. It is also well known that the grinding teeth
of animals are composed of alternate layers of hard enamel and soft bone.
This is very apparent in the teeth of the horse and of the elephant.
My Invention has for its object the formation of "mill stones," or what I
call " grinding plates," on a similar principle. I take a circular plate of cast
iron, about eighteen inches in diameter, and fasten it on the end of a shaft
about three feet in length, which projects thro' the plate about an inch. The
plate is then faced up truly at right angles with the shaft, and on it I form
a tight spiral roll of alternate layers or strips of hoops of steel, iron, or other
metal'; but I prefer steel, and of coarse paper, cotton, braid, or other suitable
substance, the hoops being about an inch and a half in width, and about
one sixteenth of an inch in thickness. And the pitch of the spiral next the
centre of the plate being about one sixteenth of an inch, and gradually
decreasing to within three inches from the circumference, which latter space
is kept at a pitch of about one hundredth of an inch. These proportions
must be varied according to the nature of the substance to be ground. This
forms the lower or driving plate. The upper one is formed in a similar way,
the spiral being laid in the reverse direction, and the shaft being about eight
inches in length, and hollow, to allow the substance to be ground to pass down
it from the hopper to between the plates. The two plates are arranged in a
frame in such a way that the faces of the spirals are parallel to each other,
and the centre of one plate distant about an inch and a half from the other.
The distance between the two plates is adjustable by means of a key under
:he brass footstep of the lower shaft, so that they may be made to grind
coarser or finer. I apply motive power to the lower shaft, and the friction
arising from the process of grinding gives motion to the upper plate which
then revolves in the same direction as the lower. I recommend that both

page_text: plates should be of the same diameter.
The advantage of this form of
plate is, that as the surface bears down in grinding a continual fresh cutting
edge is presented.
.
For the. purpose of grinding the husk off rice or other similar work,
I use plates the spirals of which are formed of alternate strips of leather,
or other suitable elastic substance, and thick cotton braid or felt; or the
plates may simply be faced with thick leather or other suitable elastic sub-
stance, or with a tough fibrous substance firmly fastened endways on the
plate.
For grinding paints or similar substances I use plates of metal or hard
porcelain or glass ground on the face but not polished, the lower plate being
plain and the upper having V-shaped grooves cut in its face, and decreasing
in size as they approach the circumference of the plate. The upper plate is
made concave in the centre to allow the material to be ground to get between
the plates, the concavity being greatest in the centre, and gradually tapering
off to the extent of one third of the radius, where it ends. Instead of
combining in the shape of a spiral the hard and soft materials of which these
grinding plates are composed, they may be put together in any other form;
as, for instance, they may form the radii of a circle; or the plate, being
divided into six or more segments by lines radiating from the centre, the
hard & soft materials may be arranged in lines parallel to those radii until
each segment of the plate is filled up. I do not confine myself to any
particular arrangement of the grinding surfaces, but I prefer the spiral, as it
is most easily made and forms an excellent surface. The speed for dry
substances may be from two hundred to three hundred revolutions of the
plates per minute, and for semi-fluids from one hundred to two hundred revo-
lutions per minute.
What I claim as my Invention is,—
Firstly, the combination of hard and soft materials for grinding surfaces as
described.
Secondly, the arranging of two plates so formed in such a way that they
are eccentric to each other.
Thirdly, the arrangement of plates for grinding paints or similar substances
as described.
In witness whereof, I, the said Robert Stirling Newall, have hereunto
set my hand and seal, this Thirteenth day of April, in the year of our
Lord One thousand eight hundred and forty-eight.
R. S. (L.S.) NEWALL.

page_text: AND BE IT REMEMBERED, that on the Thirteenth day of April, in the
year of our Lord 1848, the aforesaid Robert Stirling Newall came before our
said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according to
the tenor of the Statute made for that
purpose.
Enrolled the Fourteenth day of April, in the year of our Lord One
thousand eight hundred and forty-eight.