IM- PROVEMENTS IN THE CASINGS OF MILLSTONES AND IN THE PASSAGES AND STIVE ROOM CONNECTED THEREWITH
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by Henry Smith at the Office of the
Commissioners of Patents on the 13th March 1876.
HENRY SMITH, of Southsea, Portsmouth, in the County of Hants, Miller. "IM-
PROVEMENTS IN THE CASINGS OF MILLSTONES AND IN THE PASSAGES AND STIVE
ROOM CONNECTED THEREWITH."
My Invention has for its object to prevent the condensation of moisture in the
casings of millstones and in the passages and stive room connected therewith, and
consists of the construction and arrangement of parts herein-after described,
whereby the heat produced by the grinding process is so utilized as to maintain or
assist in maintaining the several parts of the apparatus at a temperature which will
prevent the condensation of moisture. I cover the inside of the casings of mill-
stones, as well as the inside of the stive room, and the inside of the air passages with
a covering of sheet zinc. The said sheet zinc is fixed at a little distance from the
inner surface of the case of the millstone, or from the inner surface of the air
passages or stive room, so as to leave an air space between the said sheet zinc and
the surface it is attached to. This air space is closed at all parts so that the air
contained in it while capable of circulating within it is incapable of passing out of
the said space. The heat produced in the grinding process is communicated to the
sheet zinc, and by the sheet zinc to the air in the air space, which air being
confined in the said air space equalizes the distribution of the heat, but prevents its
escape. The result of this arrangement is that a temperature is maintained
throughout the apparatus which prevents that deposition of moisture so common
and injurious in grinding machinery as ordinarily constructed.
When the parts lined with sheet zinc are of wood, the method described of
constructing the air space answers the required purpose; but when it is wished to
construct the casing or other parts of sheet metal (sheet zinc, for example), then in
consequence of the conducting power for heat of the metal I adopt the following
additional arrangement to prevent loss of heat, besides the inner lining of sheet zinc
already described :-I make another outer casing of sheet zinc, there being thus a
sheet zinc lining within the case or other part, and a sheet zinc outer casing. The
inner sheet zinc lining forms with the casing proper the air space described, while
the outer sheet zinc casing forms with the said casing proper another enclosed
space, which I fill with fine dry bran or other imperfect conductor of heat. The
metal case thus protected retains the heat as effectually as a wooden case.

page_text: In making new millstone casings I prefer to make the top of the case of wood,
with the sheet zine lining described, while I make the cylindrical part of the case
of three concentric hollow cylinders of sheet zinc, the inner and outer zinc cylinders
being on all sides about half an inch distant from the middle one.
The space
between the outer and middle cylinders is filled with fine bran; that between the
middle and inner cylinders forms the closed air space described.
Although ordinarily the heat produced by the grinding process when utilized in
the manner described is sufficient to prevent the deposition of moisture, yet when
damp wheat is ground, it may be necessary to supplement the heat produced by
grinding with a current of hot air introduced into the air space, and I provide the
air space with openings capable of being closed at pleasure, at which openings a
current of warm air may be introduced when required.