IMPROVEMENTS IN DRESSING
Year: 1858

page_text: LETTERS PATENT to Andrew Dunlop, of Moor Park Mill, in the County
of Renfrew, North Britain, Grain Merchant, and Alexander Stark, of the
same Place, Millwright, for the Invention of "IMPROVEMENTS IN DRESSING
Sealed the 17th September 1858, and dated the 18th March 1858.
PROVISIONAL SPECIFICATION left by the said Andrew Dunlop and
Alexander Stark at the Office of the Commissioners of Patents, with
their Petition, on the 18th March 1858.
We, ANDREW DUNLOP, of Moor Park Mill, in the County of Renfrew, North
Britain, Grain Merchant, and ALEXANDER STARK, of the same Place, Mill-
wright, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN DRESSING OR SIFTING FLOUR AND MEAL OR REDUCED GRAIN," to be as follows,
that is to say:-
In the
This Invention relates, in some respects, to an Invention of improvements in
dressing or sifting flour and meal, for which British Letters Patent were
granted to Andrew Dunlop on or about the 6th day of October 1856.
present arrangements, however, the dressing or sifting operation is effected by
moving the frame, to which the dressing or sifting cloth is attached, rapidly up
and down in a vertical approximately vertical direction. The dressing cloth is
preferably of silk, but it may be made of any suitable permeable fabric, such as is

page_text: used in ordinary dressing machines, and it is extended on its supporting operating
frame horizontally as regards its width, but with a slight inclination longitu-
dinally. The flour or meal to be dressed is supplied at the upper end of the
dressing fabric, and in consequence of the rapid and energetic upward and
downward motion given to the frame carrying the dressing fabric, the fine flour
or meal is quickly sifted or passed directly through the fabric into a receptacle
beneath, whilst the coarser particles which do not pass through the fabric
gradually pass down to the lower end of the latter, and are discharged into
their own special receiver. According to one modification, under which these
improvements may be judiciously carried out in practice, the dressing fabric is
attached by its edges, by tacks or otherwise, to strips of wood, and these strips
are screwed to an oblong frame so as to keep the fabric evenly extended.
The frame is moved rapidly up and down by a revolving crank arrange-
ment, or by eccentric movements beneath it, the result being that the flour or
meal is actively tossed up and let fall at each movement, and the dressing or
sifting action is thus performed with great rapidity and effect; instead of con-
fining the movement of the dressing frame to the vertical direction up and
down, a composite or differential action may be imparted to it. For example,
the action may be made to partake of horizontal and vertical movements, com-
bined or otherwise.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Andrew Dunlop and Alexander Stark in the Great Seal
Patent Office on the 17th September 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, ANDREW
DUNLOP, of Moor Park Mill, in the County of Renfrew, North Britain, Grain 2
Merchant, and ALEXANDER STARK, of the same Place, Millwright, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of March, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us, the
said Andrew Dunlop and Alexander Stark, Her special license that we, the
said Andrew Dunlop and Alexander Stark, our executors, administrators, and
assigns, or such others as we, the said Andrew Dunlop and Alexander Stark,
our executors, administrators, or assigns, should at any time agree with, and s
no others, from time to time and at all times thereafter during the term

page_text: 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 "IMPROVEMENTS IN DRESSING OR
SIFTING FLOUR AND MEAL OR REDUCED GRAIN," upon the condition (amongst
others) that we, the said Andrew Dunlop and Alexander Stark, by an instru-
ment in writing under our hands and seals, or under the hand and seal of one
of us, should particularly describe and ascertain the nature of the said Inven-
tion, 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 Andrew Dunlop and Alexander
Stark, do hereby declare the nature of our said Invention, and in what
manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement, reference being had to the accom-
panying Drawings, and to the letters and figures marked thereon, that is
to say:
:-
Our said Invention relates in some respects to an Invention of " Improve-
ments in Dressing or Sifting Flour or Meal," for which British Letters Patent
were granted to the said Andrew Dunlop, on or about the Sixth day of October,
One thousand eight hundred and fifty-six. In the present arrangements,
however, the dressing or sifting operation is effected by moving the frame, to
which the dressing or sifting cloth is attached, rapidly up and down in a
vertical or approximately vertical direction. The dressing cloth is preferably
of silk, but it may be made of any suitable permeable fabric, such as is used
in ordinary dressing machines, and it is extended on its supporting operating
frame horizontally as regards its width, but with a slight inclination longi-
tudinally. The flour or meal to be dressed is supplied at the upper end of the
dressing fabric; and in consequence of the rapid and energetic upward and
downward motion given to the frame carrying the dressing fabric, the fine flour
or meal is quickly sifted or passed directly through the fabric into a receptacle
beneath, whilst the coarser particles which do not pass through the fabric,
gradually pass down to the lower end of the latter, and are discharged into
their own special receiver. According to one modification under which these
improvements may be judiciously carried out in practice, the dressing fabric
is attached by its edges, by tacks or otherwise, to strips of wood, and these strips
are screwed to an oblong frame, so as to keep the fabric evenly extended
The frame is moved rapidly up and down by a revolving crank arrangement
or by eccentric movements beneath it, the result being that the flour or meal
is actively tossed up and let fall at each movement, and the dressing or sifting

page_text: action is thus performed with great rapidity and effect. Instead of confining
the movement of the dressing frame to the vertical direction up and down, a
composite or differential action may be imparted to it. For example, the
action may be made to partake of horizontal and vertical movements, combined
or otherwise. And in order that our said Invention may be properly under-
stood, we shall now proceed to describe the several Figures upon the explanatory
Sheet of Drawings which we have hereunto appended for the purpose of
showing certain modifications under which our improvements may be
judiciously carried out in practice.
Figure 1 on our Sheet of Drawings is a longitudinal elevation of one
modification of our improved machine for dressing or sifting flour and meal or
reduced grain; Figure 2 is a transverse vertical section taken at right angles
to Figure 1. The framing A of the machine is in this modification of wood,
and consists of end and central standards united by longitudinal and transverse
rails. The longitudinal rails B are fitted so as to incline towards one end of
the machine, as shown in Figure 1 of our Drawing; these rails, together with
those at the ends of the machine, form with the standards an oblong frame.
The sides and ends of this rectangular frame are enclosed at the lower part by
a closely fitting casing of wood C, the separate lengths of wood which form
this casing being screwed or otherwise fastened to the framing A and rails B,
or this portion of the machine may be made so as to be readily removed if
required. The upper part of the frame is enclosed by the moveable frames D,
which are made to fit the space between the standards A. The lower edge of
these frames rest upon the upper edge of the casing C, and the frames are
securely fastened in their respective compartments by means of buttons, as
shown in Figure 1 of our Drawing, or other suitable attachments. The open
portion of each of the frames D is covered in with cloth as shown at E, so
that when the side and end frames are in their places, the space within the
fraimog A and B is enclosed on all sides. In our illustrative Drawing the
casing C and the frame D of the left-hand portion of Figure 1 are omitted in
order to show more clearly the internal arrangement of the machine. Inside
the framing A and B is arranged a rectangular frame of wood F, which
inclines in a direction parallel to the rails B. At each corner of the frame F
is fastened a piece of hard wood G, the surface of which is made smooth;
these pieces of wood slide up and down the metal guides H, each of which is
secured to the end cross rails I, which are indicated by dotted lines in
Figure 1 of our Drawing. In this manner the frame F moves freely up and
down within the guides H, but has no lateral or longitudinal motion. To the
.sides of the frame F are screwed or otherwise fastened the vertical pieces of

page_text: wood J, which serve to support the light rails K, that form a rectangular
frame parallel to the frame F. The dressing cloth L, which is preferred
to be of silk, is extended upon and fastened to the frame F. The edges
of the silken fabric are in the first place strengthened by pasting or other-
wise attaching thereto strips of calico of about two inches wide, forming
a kind of selvage to the dressing cloth. The edges of the dressing cloth,
prepared in this manner, are next fastened to strips of wood; about one
inch in breadth of the selvage of the dressing cloth is laid upon the strip
of wood, and upon this another and corresponding strip of wood is laid,
which is glued and fastened by screws to the lower one; the duplex strips of
wood are then screwed or otherwise firmly secured to the frame F, as shown
at M, in Figures 1 and 2 of our Drawing. The dressing cloth L does not
extend to the lower cross rail of the frame F, but terminates in a flexiblo
shoot N, which extends downwards to the lower part of the machine. In
fitting the dressing cloth to the frame F, it is made to bag down a little in
the centre so as to be about half an inch below the level of its edges, in order
to give it a high degree of elasticity when put in motion, as will presently be
described, and thus prevent the fine flour from choking up the interstices.
The dressing cloth is enclosed on all sides so as to form a chamber in which
the flour to be dressed is received, the sides of the chamber being enclosed
by the side cloths O, and the upper part by the covering cloth P, which is put
on tightly. These cloths are fastened to the frame F and the rails K. The
sifting or dressing operation is effected by imparting to the frame F a rapid
vertical or approximately vertical motion from two crank shafts Q and R,
fitted equidistant from each extremity of the frame F. These crank shafts are
carried in pedestal bearings which are bolted to the longitudinal rails B; the
left hand shaft Q has fitted to one of its extremities a pulley S, which is
driven by means of an endless belt that is actuated from a steam engine or
other prime mover. The pulley S has projecting from its outer face a crank
pin T, to which one extremity of the connecting rod U is attached, the other
end of this rod is secured to the crank V on the end of the shaft R. The
crank shaft Q has keyed to its other extremity the crank X, which is con-
nected by means of a rod similar to that shown in Figure 1, with the oppo-
site extremity to the shaft R, the pins of the cranks on the shaft Q being
fixed at right angles to each other, and the pins of the cranks on the shaft R
being fixed in a similar manner. The cranked parts of the shafts Q and R
are in this manner caused to move in unison with each other, when the pulley
S is put in motion, and the frame F being connected to these shafts, a cor-

page_text: responding rapid vibratory movement is imparted thereto. To the under side of
each of the longitudinal rails of the frame F, are fixed two open frames Y, which
are fitted so that the cranked parts of the shafts Q and R are in the centres
of each pair of frames Y. Each of the cranks on the shafts Q and R are
encircled by the sliding blocks Z, which are composed of two pieces of hard
wood bolted together, and accurately fitted to the journals of the cranks. The
upper and lower faces of the sliding blocks Z are flanged to prevent them from
moving laterally in the frames Y, in which they are fitted so as to slide freely
to and fro therein in a longitudinal direction. When the pulley S is put in
motion, the blocks Z having no play in a vertical direction, the frame F
rises and falls with the vertical motion of the cranks upon the shafts Q and
R. The motion of the cranks in. the horizontal direction does not affect the
frame F, as the blocks Z are free to traverse to and fro in the openings of the
frames Y. The flour to be dressed is fed into, the sifting chamber through the
flexible shoot a the rapid upward and downward motion of the frame carry-
ing the dressing cloth causes the flour to be tossed with great rapidity up and
down upon the dressing cloth L, and this action drives the fine particles of
The dressed flour or
flour through the interstices of the dressing material.
meal falls from the dressing cloth into the receiver b, which is formed by
extending cotton, cloth, or other suitable material downwards, so as to form a
chamber beneath the frame F, as shown by the diagonal lines in the lower
part of Figure 2 of our Drawing. The coarser particles of flour or meal
which are too large to pass through the dressing cloth, gradually descend the
inclined surface of the cloth L, and pass through the cloth shoot N into the
receiver c, fitted for their reception at the lower end of the frame F. If it is
desired to impart a beating action to the frame F, it may be readily obtained
by allowing a certain amount of play between the pieces of wood G and the
metal guides H. Or a similar effect may be obtained by fitting the sliding
blocks Z loosely in the frames Y, so as to have the requisite amount of play in
a vertical direction. The mechanical arrangement for actuating the dressing
chamber may be variously modified so as to produce the vertical or compound
vibratory movement either from above or below, and in other ways without
adhering precisely to the construction herein-before described.
Having now described and particularly ascertained the nature of our said
Invention, and the manner in which the same is or may be used or carried
into effect, we may observe, in conclusion, that we do not confine or restrict
ourselves to the precise details or arrangements which we have bad occasion
to describe or refer to, as many variations may be made therefrom without

page_text: deviating from the principles or main features of our Invention; but what
we consider to be novel and original, and therefore claim as the Invention
secured to us by the herein-before in part recited Letters Patent, is,―
First, the general arrangement and construction of machinery or apparatus
for dressing or sifting flour and meal, or reduced grain, as herein-before
described.
Second, the system or mode of dressing or sifting flour and meal, or reduced
grain, in which the flour is subjected to a rapid vibratory motion in a vertical
or approximately vertical direction, or in vertical and horizontal directions
combined, by means of the mechanical arrangement herein-before described,
or any mere equivalent therefor.
Third, the system or mode of extending the dressing cloth on the frames of
dressing machines in which the fabric is arranged horizontally as regards its
width, and a slight inclination longitudinally, in such manner that the fabric
hangs loosely or bags down in the centre, by which means a greatly superior
sifting effect is obtained as herein-before described.
Fourth, the system or mode of arranging the sifting chamber, and of im-
parting to it a vertical reciprocatory action, or a compound vertical and hori-
zontal motion by the mechanical means herein-before described.
In witness whereof, I, the said Andrew Dunlop, on behalf of the said
Alexander Stark, and of myself, have hereunto set my hand and seal,
this Sixteenth day of September, One thousand eight hundred and
fifty-eight.
ANDREW DUNLOP. (L.S.)