COINING. 103 
they are in motion, not on that side of the roller which would operate to 
draw in the slip between them, as in the rolling-press above described, 
but on the contrary side, so that when one of the flat sides of the under 
roller fronts horizontally the circumference of the upper roller, an opening 
is formed, through which the bar is to be inserted until it bears against a 
fixed stop at the back of the rollers. As the rollers continue to revolve, the 
cylindrical portions come opposite to each other, and press the metal, fore- 
ing it outwards, and rendering the part introduced between the rollers as 
thin as the space between their cylindrical surfaces; thus the end of the 
slip of metal becomes attenuated enough to pass between the dies of the 
drawing machine and to be seized by the pincers. The drawing plate is 
seen in pl. 20; jig. 14 shows the die-box; the dies are adjusted vertically 
and horizontally, by means of the screws dd and gg. 
The bars are now heated and cut into lengths of about 4 feet, and if, as is 
the case in the English mint, the breadth is twice or three times as great 
as that of the coin to be struck, it is also cut through lengthwise. This is 
effected by means of circular shears, seen in jigs. 5 and 6; fig. 6a shows 
the cutting wheels, with the bars lying between them. 4G is an adjustable 
ledge, against which the metal plate rests, to regulate the width of the strip 
to be cut off. 
3. Tar Currine Out. Pl. 20, jig. 15, presents a side-view, and jig. 16 a 
top-view of acoin-punch. £ is a hollow cast-iron column, from which the 
atmosphere is kept constantly exhausted; G is a cylinder with a hollow 
axis, around which it can revolve on the frame #; by means of the tube x 
the air can be exhausted from the cylinder when required, and motion 
imparted to the piston in the same, the pressure of the atmosphere upon the 
piston carrying the punch, c, down, and the fly-wheel, p, raising it again, and 
returning it to a position ready for another downward stroke. 
The blanks cut out by the above machine are then tested, and smoothed 
upon the surface. 
4. Mituive. The polished blanks are next milled upon the edge, which 
operation precedes the stamping, and is performed by a machine shown in 
pl. 20. Figs. 19 @ and 6 are the two milling plates, on the edges of which 
is engraved the device or motto to be impressed upon the edge of the coin ; 
to the plate a is imparted a reciprocating motion by the rack bar e, and the 
blank being laid upon the arm / is forcibly compressed between the plates 
a and b, and passes out at g. 
A milling machine is seen in jig. 20, by which a single workman can 
mill 20,000 large coins in one day. The two milling plates & and p contain 
each upon their curved edges one half of an inscription for the edge of the 
coins; one of these plates is secured firmly to the bed of the machine, the 
other to the vibrating lever pp, which turns upon an axis, c; @ is a tube 
which supports a pile of blanks, and having an opening at the bottom just 
sufficient to permit one of these blanks to pass out at a time. As the lever 
pp is moved, the arm cp attached to it carries out the lowest blank of the 
pile, which is moved from a towards x, between the milling plates © and p, 
and finally passed out at 6. More recently, in order to improve the appear- 
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