IMPROVEMENT OR IMPROVEMENTS IN THE METHOD OR APPARATUS FOR SEPARATING THE KNOTS FROM PAPER STUFF OR PULP USED IN THE MANUFACTURE OF PAPER
Year: 1830

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, RICHARD
IBOTSON, of Poyle, in the Parish of Stanwell, in the County of Middlesex,
Paper Manufacturer, send greeting.
WHEREAS His present Majesty King William the Fourth, by His Letters
Patent under the Great Seal of the United Kingdom of Great Britain and
Ireland, bearing date at Westminster, the Twenty-ninth day of July now
last past, did give and grant unto me, the said Richard Ibotson, His especial
licence, full power, sole privilege and authority, that I, the said Richard
Ibotson, my executors, administrators, and assigns, or such others as I, the said
Richard Ibotson, my executors, administrators, or assigns, should at any time
agree with, and no others, from time to time and at all times thereafter during
the term of years therein expressed, should and lawfully might make, use, exer-
cise, and vend, within England, Wales, and the Town of Berwick-upon-Tweed,
my Invention of an "IMPROVEMENT OR IMPROVEMENTS IN THE METHOD OR APPARATUS
FOR SEPARATING THE KNOTS FROM PAPER STUFF OR PULP USED IN THE MANUFACTURE
OF PAPER;" in which said Letters Patent there is contained a proviso obliging
ne, the said Richard Ibotson, by an instrument in writing under my hand and
seal, particularly to describe and ascertain the nature of my said Invention,
and in what manner the same is to be performed, and to cause the same to
be inrolled in His said Majesty's High Court of Chancery within four
calendar months next and immediately after the late of the said recited
Letters Patent, as in and by the same, reference being thereunto bad, will
more fully appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Richard Ibotson, do hereby declare, that the nature of my said Invention, and
the manner in which the same is to be performed, are fully described and
ascertained by the following description thereof, that is to say :-
The nature of my said Invention consists in the peculiar construction of a
sieve or strainer, which will be better understood by paper makers in general
who are acquainted with the difficulty hitherto existing in paper manufactories,
of separating the knots (which are frequently found in the stuff or pulp of
which paper is made) from the pulp previously to its being made into paper by
stating, that when sieves or strainers made of wove wire are tried for separating
the knots from the paper stuff, the said sieves soon become stopped up and
will not allow the pulp to pass through them. Sieves of this kind are
necessarily made of very fine wire, that is to say, there must be a great many
wires or holes to the inch, and consequently the diameter of each individual
wire must be a very small fraction of an inch. Paper stuff or pulp consists of
an assemblage of very fine flexible fibres of flax, hemp, cotton, &c., mixed
with water; and in all cases, even in pulp of which the finest paper is made,
it will be found that the length of by far the greatest number of the said fibres
considerably exceeds the diameter of the wires of which the strainer is formed;
consequently, the smallness of the wires and of the spaces between them, as
compared with the length of the fibres, prevents many of the said fibres from
flowing through the sieve along with the water. Now, the nature or principle
of my said Invention is, that instead of making use of round wire, either woven
or otherwise, for the purpose of making a strainer, I make use of a number of
bars of brass, copper, or other fit material of about half an inch in width, and
of any convenient thickness. I make the upper side of each of the said bars,
as also the edges thereof, as nearly straight, flat, and smooth as possible; and
I fix a number of such bars side by side to the bottom or under side of a
wooden or metallic sieve frame of a rectangular shape, so as that the upper
surfaces or the flat sides of all the said bars lie in the same plane, and so as
that the edge of each bar is parallel with the edge of the neighbouring bar,
thereby leaving between every two bars a parallel slit, opening, or space of
from about one seventieth to about one hundredth part of an inch in width;
and I make the width of the said spaces less or more, according to the fineness
or coarseness of the paper stuff or pulp to be strained. The only rule I have
for determining the width of the said bars, with which I form the bottom of
the said sieve or strainer, is, that the said width, according to my experience,
should equal or exceed the length of the longest fibres which compose the
paper stuff or pulp to be strained; the width of the said bars may therefore be

page_text: varied beyond that width, at the discretion or convenience of the paper maker
or the maker of the sieve.
I shall now proceed more particularly to describe the manner in which the
said sieve or strainer is constructed and used; but first stating that the sieve I
have now in use is employed to strain the paper stuff previously to its being
made into paper by one of the machines known by the name of Fourdrinier's
Patent Paper Machines; and that the length of the said sieve or strainer, as
herein-after mentioned, is such as suits the width of that individual machine;
but the length of such sieves or strainers as are herein described may be
made to suit any paper machine, or to suit any vats from which paper is made
by hand. And I would also state, that although I shall herein-after mention
the precise dimensions of the strainer which I have made for my own use,
I believe that these dimensions will admit of being varied, but to what extent
my experience as yet does not warrant me to state. I make my said strainer
in the manner following, that is to say, I make the frame of the said strainer
of a rectangular shape, about five feet along, and eighteen inches wide inside,
the sides and ends of which, when made of metal, are about four inches deep,
and about half an inch thick. The metal I prefer for this purpose is that
known by the name of gun metal. The lower edges of the sides and ends of
the said frame I cause to be made perfectly straight, and out of wind with
each other; I then prepare a number of bars of any suitable metal, but I
prefer brass or gun metal, of a length equal to the exterior width of the said
strainer frame; the width of each of the said bars, as has herein-before been
mentioned, I make about half an inch. And the shape of a transverse section
of one of the said bars I make so as to somewhat resemble the shape of the
letter T, in which the metal forming the cross stroke at the top of the T is
about the eighth of an inch thick, and that forming the upright stroke of
about the same thickness, and about three quarters of an inch deep, so that
each of the said bars are cast with a strengthening rib on the under side
thereof. For about one inch or one inch and a quarter at each end of each
of the said bars, the said rib is discontinued, for the purpose of more con-
veniently forming holes through the ends of the said bars, by which each bar
may be fastened by screws to the bottom of the said frame. Having prepared
a sufficient number of the said bars, and having made their upper surfaces and
their edges as nearly straight and smooth as possible, and both edges of each
bar as nearly parallel with each other as possible, I proceed to make them fast
to the bottom of the said sieve frame, by screwing them to the sides of the
said frame, with one or more screws at each end of each of the said bars,
taking care that the opening or distance between every two bars shall be the

page_text: same, or as nearly so as possible, from end to end of the same bars, and that all
the openings between the said bars, from one end of the sieve to the other,
shall be as nearly as possible of the same width. I prefer making the upper
surfaces of the said bars flat, in order to facilitate the removal of any knots
or other matter collected in the said strainer, and also because in that form
the strainer is less liable to be choked up or clogged than if the said bars
were made of any other shape. The said strainer is placed in a horizontal
position, or nearly so, in the top of the vat, so as that when the vat is filled
to the proper height with the paper stuff or pulp, the upper surface of the
said bars should be about one quarter of an inch above the surface of the said
fluid pulp in the vat, and so as that the ribs on the under side of the said bars
shall dip into or be partly immersed in the said pulp. I cause one side of the
said strainer to be supported by fixing a pivot to each end of the said side,
and I make each pivot to lie or rest upon appropriate bearing pieces fixed to
the inside of the vat, so as that the said pivots have their axes in the same
straight line, and that the said line shall be parallel to the side and bottom of
the said strainer, or nearly so. One side of the said strainer is supported in
this manner, in order that the other side thereof may be raised or lowered, so
as to give a motion to the said strainer similar to the motion of the lid of a box
or chest when moved upon its hinges. When the said strainer is at work, I cause
a quick up-and-down or jogging motion to be given to the other side thereof,
similar to the motion given to the well known machines employed in corn mills,
commonly called jumpers or joggling screens, and this I effect by any of the
well known means, such as cranks or cam wheels, which are usually employed
for producing jumping or alternating motion, but at present I employ two cam
wheels, with three cams upon each wheel; these two wheels are about four
inches in diameter, and about one inch in width, and are fixed or hung on an
iron spindle or axle; the said axle is placed horizontally, and is made to turn in
two bearings fixed to the front of the vat in which the said strainer works,
and the said axle is on the outside, and a little above the front side of the said
vat, and parallel therewith. To each end of the said sieve (which is on the
inside of the said vat, having its sides parallel to the said front side of the said
vat), I fix a bar or arm of wood, brass, or gun metal, one end of each of the
said bars is fastened by bolts or screws to one end of the said strainer, and the
said two arms are of such a length that the other ends thereof extend beyond
the side of the said strainer as far as the aforesaid spindle or axle on the out-
side of the said vat; and the said two arms are made of such a shape as that
the said other end thereof may pass over the front of the vat, and lie, upon
the cam wheels herein-before mentioned... I may here notice that the said

page_text: cam wheels, with relation to the three cams upon each of them, are so hung on
the said spindle as that when the said spindle and wheels are made to revolve,
both of the aforesaid arms, which are fixed to the ends of the said strainer,
may be struck or raised by each of the cam wheels respectively; at the same
time I cause a rotary motion to be given to the said spindle and cam wheels
by cog wheels or otherwise, so as that the said spindle and cam wheels
shall make about sixty revolutions in a minute or (if more than three cams
are employed in each wheel), so as that the said strainer may thereby be made
to jump or jogg about one hundred and eighty times in a minute; and I make
the length of the cams upon the said cam wheels such as to cause the move-
able side of the said strainer to be lifted about one eighth of an inch at every
stroke or jump. The pulp to be strained through the said sieve or strainer is
brought from the stuff chest in the usual way, well known to paper makers,
and falls into the vat at the opposite side to that occupied by the strainer;
but in order that the said stuff and the water may be well mixed together, by
what in paper mills is commonly known by the name of a hog, my vat
is divided into two compartments, by a vertical partition placed a few inches
from the hinge side of the said strainer; and the top of the said partition is
about an inch higher than the top of the said strainer. In the bottom of the
compartment at the back of the vat I cause a hog to be worked in the usual
way, and immediately over the axis of the said hog, and parallel therewith, I
place another vertical partition, the lower edge of which is about an inch above
the arms of the said hog, so as to leave room enough for the said hog to
revolve below the lower edge of the said partition. The upper edge of the
said partition is made to rise about three inches about that of the said first-
mentioned partition; thus a space is left between the back of the said vat and
the said partition, which is placed above the said hog, and both the pulp and
the water are made to run first into the said space; consequently, before the
said pulp and water can make its way from the space between the back of the
vat and the said partition into the next space, between the said two partitions,
the said pulp must descend and pass through that part at the bottom of the
vat occupied by the hog, where it undergoes the necessary agitation or mixing
by the motion of the said hog, and is by this means brought into a fit state to
be strained. To the upper edge (which is horizontal) of the said first-
mentioned partition, I affix a copper lip or spout for the purpose of conveying
the stuff, as it flows up between the said two partitions, from thence into the
said strainer in a regular and uniform thin stream, nearly as wide as the said
strainer is long. The knots or other matter, which from time to time
accumulate on the bottom of the said strainer when at work, I remove at
intervals by a narrow hair brush, the length of which is a little less than the

page_text: width of the said strainer. Although I have herein-before described the whole
of the aforesaid bars as being fixed to the bottom of the said strainer, in such
a manner as would occasion the spaces or openings between the said bars, to
be permanently of the same width, I have found it convenient to employ
another mode of constructing a strainer, on the same principle, by which I
procure the facility of altering the width of the said spaces between the said
bars, so as to suit the various kinds of paper stuff which may require straining.
For this purpose I vary the form of each of the said bars, that is to say,
instead of making the sides of each bar parallel to each other, I make the upper
surface or side of each of the said bars taper, and I make one half of the
whole number of the said bars required to form the bottom of the said
strainer of a length equal to the exterior width of the said strainer frame,
which I shall herein-after call the shorter or fixed bars; and I make the
other half of the said whole number of bars about five inches longer than the
last-mentioned shorter bars. The width of the upper surface of cach of the
said shorter bars is half an inch at one end, and one inch at the other; thus
the said shorter bars are made to taper about half an inch, and for the purpose
herein-after to be explained, I make the angle of the taper of the longer set
of the said. bars to exactly correspond to or be exactly equal to the taper
given to the said shorter bars. For the sake of illustration, I will suppose the
length of the said shorter bars to be nineteen inches, and: the length of the
said longer bars to be twenty-four inches; then at two inches' distance from
the wider end of each of the said longer bars I make the width of the upper,
surface thereof one inch, and at twenty-one inches from the said wider enil of
each of the-said-longer-bars-I-make-the-upper surface-thereof-of-thie-width-of-
half an inch, thus making the angle of taper in all the said bars exactly alike
as possible. By way of further illustration, I will suppose one of the said longer
bars to be laid between two of the said shorter bars, so as that they lie close
to each other, having their upper surfaces all in the same plane, and so as that
the wider end of the longer bar lies between the narrower ends of the two
shorter bars, and I will also suppose that a straight line be drawn from the
upper surface of the said longer or middle bar, from one end thereof to the
other, so as to exactly bisect the said surface. Now, if the wider end of the
said middle or longer bar. be drawn back a little from the narrower
ends of the said shorter bars, and at the same time causing the said
bar to move exactly in the direction of the aforesaid straight line, it
will be evident that the said middle bar will no longer completely occupy:
the space between the said two shorter. bars, and that an opening will
have been made between each side of the said longer bar, and the corre=:
sponding side of each of the said shorter bars, and that such? openings may

page_text: be increased or diminished at pleasure by moving the said middle or longer
bar in the direction of the line, as herein-before mentioned, by drawing it
further out or pushing further in between the aforesaid two shorter bars.
According to this principle, I fix the said shorter set of the said bars to the
sides of the aforesaid rectangular strainer frame, so as that a middle line on
the surface of each of the said bars; drawn as has herein-before been supposed,
would be at right angles, or as nearly so as possible, with each side of the
said rectangular strainer frame, and I fix the wider ends of all the said shorter
bars to one side of the said strainer frame, and all the narrow ends of the
said bars to the other side of the said frame, so as that the spaces between
all of the said bars shall be one inch at the narrow ends and half an inch at
the wider ends thereof, and so as that one of the said longer bars when
interposed between any two of the said shorter bars shall completely fill the
space between any two of the said shorter bars. In this manner I place
a short bar and a long one alternately across the said strainer frame throughout
its whole length, with the wider ends of all the said shorter bars on that
side of the said strainer frame which is nearest to the front side of the vat,
and the wider ends of all the said longer bars on that side of the said strainer
frame which is nearest to the back of the vat. It will be understood that
when the said shorter bars have been fixed as herein-before described, and
the said longer bars have been made to occupy the intermediate spaces
left between every consecutive pair of the said shorter bars, the wider ends
of all the said longer bars will project beyond the narrower ends of the
said shorter bars about two inches towards the back of the vat, and that
the smaller ends of the said longer bars will extend beyond the wider ends
of the said shorter bars about three inches towards the front of the vat.
It will also be evident that in this situation of the longer and shorter bars
relatively with each other, the edges of every two consecutive bars (if the said
edges have been previously made perfectly straight) will lie so closely in contact
each other as to leave no opening or space between them. Whilst the said
with bars are in the situation last mentioned, I cause a strong rectangular bar
of brass or gun metal, about one inch and a half wide and an half an inch
thick, and of the same length as that of the said strainer frame, to be laid
upon the upper surfaces of the wider ends of the said longer bars, and to
the said rectangular bar I cause the wider ends of all the said longer bars
to be firmly fixed by screws or rivets; I also cause another bar of gun metal
or brass, of a similar shape and of the
manner upon the upper surfaces of the
bars, so that all of the said bars may be
same length, to be fixed in a similar
narrower ends of all the said longer
retained and securely held in their

page_text: proper places and at the proper distance from each other. From the fore-
going description it will have been understood that the whole of the said
longer bars, having been securely fastened to the said two long rectangular
bars, constitute a kind of frame or grating, which admits of being drawn
or moved to a certain extent from the front towards the back of the vat,
and again referring to a straight line bisecting the upper surface of one of
the said longer bars. If the said grating or all of the said longer bars at
once be moved together in the direction of the said straight line towards
the back of the vat, the edges of the said longer bars will not then lie in
contact with or close to the edges of the said shorter bars, and that there
will be a space between every two consecutive bars, a long one and a short
one, throughout the whole length of the said strainer. The aforesaid
moveable grating is supported and held up against the under side of the
said strainer frame by any of the well known expedients, such as straps
or brackets, &c., fastened to the said strainer frame, so as that the said grating
may be allowed to slide backwards or forwards upon the said supporting
brackets; and in order to cause the said grating to move backward or forward
whenever it may be found necessary that it should do so, I apply adjusting
screws at each end of the said grating, or I effect the same by racks and
pinions, in which last-mentioned case I employ an axle or spindle lying
parallel with the back side of the said strainer frame, and on the outside
thereof, and I cause the said spindle to turn in two bearings fixed upon
the last-mentioned side of the said frame, one of the said bearings near
each end of the said side.. Upon the said spindle I fix or hang two pinions,
so as that one pinion is placed or hung on the said spindle near to each
of the said bearings, and I cause the teeth of each of the said pinions to
take or work in the teeth of two racks, both of which racks are fixed upon
the aforesaid rectangular bar of gun metal to which the wider ends of the
said longer bars are fastened, so that by turning the aforesaid spindle and
pinions thereon I am enabled to move the said grating, or to move the whole
of the said longer bars simultaneously backwards or forwards, and thereby
increase or diminish the openings between all of the aforesaid longer and
shorter bars.
I lastly declare that my Invention consists in making the bottom of a
sieve or strainer of a number of bars, such as have herein-before been des-
cribed, or having parallel spaces between every two of the bars which are
adjoining to each other, and in making the width of each bar such as that
the said width shall be equal to or exceed the length of the fibres composing
the paper stuff or pulp to be strained, or in making the bottom of the said