R O L L I N 
aud in the interval of returning the iron, to put it through 
again, -there is no other resistance than that of the friction of 
the machinery. Again, when the iron has been passed through 
several times, the resistance is greatest of all, because the metal 
has become harder, both by the compression it has undergone, 
aud from being gradually cooled; also, the metal, being 
thinner, will not yield so readily to the pressure, as when in a 
larger mass. By the proper addition of a heavy fly-wheel, 
great advantages, in point of power, are gained, as it tends to 
equalize all these irregularities; and in every interval, when 
the resistance is removed, the water-wheel gives a rapid 
motion to the fly, the force of which will be returned when 
the work is applied : in such a mill, if the workmen have an 
extraordinary large piece of metal to roll, they suffer the 
mill to work for a few seconds without any resistance, then 
putting in the iron, it is carried through at once by the 
momentum of the fly, though requiring a power far beyond 
the ordinary force of the water-wheel. The most approved 
method of applying a fly-wheel to a rolling-mill, is to have 
a large cog-wheel upon the axis of the water-wheel, to give 
motion to a pinion, upon the axis of which a heavy iron fly¬ 
wheel is fixed: the wheel and pinion are of such a size as to 
make the fly revolve about three times to one of the water¬ 
wheel : at the opposite side of the great cog-wheel another 
pinion, of about half its size, is placed, and to the extremity 
of its axis produced, the rollers are connected, the two rollers 
being made to turn together by means of pinions upon the 
ends of their gudgeons, in the manner shewn at d e, fig. 3. 
If more than one pair of rollers is to be worked, a cog-wheel 
is fixed upon the axis which turns the rollers, and works 
another equal wheel upon the axis of the second pair, placed 
parallel to the'former; in this case the lengths of the two 
axes must be different, so that the lines in which the bars 
will come through the different rollers, will not interfere with 
each other, but leave sufficient room between for the men to 
work. In most common mills, rollers, such as are repre¬ 
sented at figs. 1, 2, 3, are employed ; but to these there are 
some objections; first, the four nuts a, a, cannot all be 
turned at once with such precision as to bring the upper 
roller exactly parallel to the other; the means the workmen 
use for this, is to have a small iron wrench, or handle, fitted 
upon two of the nuts, a, a, and these they turn round a small 
quantity every time the metal has passed through, in the in¬ 
terval whilst it is returned to be put through again. The 
•workman who stands in front to introduce the metal between 
the rollers, turns the nut on his left-hand side which is near¬ 
est to him; whilst his comrade, who receives the metal, and 
hands it back again to him over the roller, turns the nut on 
the opposite corner of the frame: by this means, as only 
two, instead of four, of the nuts are turned, the pieces D are 
constantly put out of the horizontal position, in which alone 
they can take a proper bearing; also, in these frames there 
is no support for the weight of the upper roll; but when 
there is no metal beneath it, it falls down, and rests upon the 
other; when the metal is suddenly introduced, it lifts the 
roll up to its bearing with a jerk, which endangers the break¬ 
ing of some of the parts, and generally causes the nuts to 
start a little before they settle themselves to the strain. 
In the modem mills, the frames for the rollers are made of 
cast-iron, as shewn at figs. 4 and 5. The cheeks, A, are cast 
in one piece, and form a bed for the reception of the brass of 
the lower roller, H; a piece, C, is fitted upon the top of the 
cast-iron cheeks, and is held down by two strong wrought- 
iron bolts, with nuts, a, b, to screw it down, and regulate 
the distance between the two rollers, the gudgeon of the 
upper roller, G, being confined by a brass let into the piece 
C, but to bear it up from falling: when there is no iron 
between the two rollers, another brass is placed beneath the 
gudgeon, G, and suspended by bolts, d,d, from the piece C; 
by this means the two rollers are retained always at a proper 
distance asunder. The two standards A, B, fig. 5, at the 
opposite end of the rollers, have broad feet at bottom, by 
means of which they are bolted down to massive ground¬ 
sills, which extend all across the mill-house. The rollers 
E and F are caused to move together equably by means of 
G - M I L L. J99 
pinions a, 6, which, that they may work well, are made 
with accurate teeth, of not more than 1| or 2 inches pitch, 
or distance asunder ; and, to give the requisite strength, 
they are made of considerable breadth, as the figure shews. 
Two large flat iron plates, I and K, are screwed to the two 
standards, both to strengthen them, and to form a table, 
upon which the masses to be rolled are laid to be presented 
to the rollers, and having passed through, are received on 
that at the opposite side. 
The rollers shewn in figs. 4 and 5, have a number of 
grooves in them, which, being opposite to each other, leave 
openings of a determinate figure for the purpose of rolling 
square bars, with the angles upwards; they do not there¬ 
fore require to be adjusted in distance, as other plain rollers 
do, but are always, after the first erection, retained at the 
same distance; in this case the pinions a and b serve very 
well to connect the motions of two rollers together; but 
when the rollers are required to be adjusted during the work¬ 
ing, as in the Plate Rollers, fig. 3, the pinions must neces¬ 
sarily have very coarse and long cogs, that they may not be 
so much affected by increasing or diminishing the distance 
between their centres; in this case they work very indiffer¬ 
ently, and frequently break by the awkward manner in 
which such coarse teeth always meet each other when upon 
wheels or pinions of small radius, particularly when the 
proper distance between their centres is not preserved. As 
a partial remedy for this difficulty, the pinions are, in some 
mills, made very broad, with fine teeth, and mounted in a 
separate frame, exactly similar, except in its strength, to that 
of the rollers; this is placed at a distance of three or four feet 
from the rollers; then a coupling, or short shaft, being inter¬ 
posed between the squares at the ends of the axles of the 
pinions, and those of the rollers, they permit the latter to be 
adjusted without disturbing the pinions; and the length of 
the shafts will accommodate for the differences between them. 
A rolling-mill generally contains a pair of shears, of a suf¬ 
ficient strength to clip off the ends of the largest iron bars, 
to reduce them to lengths or pieces of a sufficient size for 
laminating into thin plates. These are made different from 
other kinds of shears, in the circumstance that the cutting 
parts, or edges, are situated between the centre pin or joint, 
and the part or handle where the power is applied: the latter 
is of great strength, and made exceedingly strong in iron. 
The shears are fixed in a vertical position ; the upper blade 
being firmly fixed by the framing, and the lower one, which 
is the long lever, is lifted up by the mill when the cut is to 
be made; therefore it descends when the shears are to open, 
and its own weight is sufficient for that purpose. The frame 
consists of a very large and thick iron plate, which is securely 
bolted down to the foundations: at one end is an upright, 
which has a groove through it, to receive the moving blade, 
and guide it; also the end of the handle of the stationary or 
upper blade is supported by the upper end of this upright. 
The joint-pin of the two blades is supported in a strong 
socket, or iron frame, also erected from the same large plate, 
which carries the upright guide at its other end. The two 
blades, therefore, lie side by side, and having cutters, or 
blades, of steel, let into the adjacent sides of the iron levers 
or blades, the edges of these pass by each other when the cut 
is made, and will thus cut any thing which is interposed 
between them, in the same manner as shears or scissars. 
Rollers are usually made of cast-iron, and are very exactly 
turned on their surfaces, and also their necks, that they may 
turn truly when put in their places. The most common way 
of turning them is, first to mount the roller in a strong 
turning lathe, by holes or centre points made in its ends; 
then to turn the two necks truly cylindrical; and afterwards 
putting the roller in its proper place in the roller-frame, and 
placing brasses over the necks, they are held down by blocks, 
fitted under the pieces which retain the gudgeons of the 
upper roller: in this situation it is put in motion by the mill, 
and a bar of iron being fixed up for a rest, the surface of the 
roll is turned true, in the same manner as if it was in a lathe, 
and will be certain to be exact, being formed from the same 
necks on which it is afterwards to work. In casting a roller. 
