- COINING, - 105 
the steam to the stamping mill. 7. 21, jig. 1, shows an outline of the 
stamping machine in the mint at Rio Janeiro. Eight stamping mills are 
arranged around the receptacle, a,in which is kept a constant vacuum. The 
vertical stamping screws are moved by chains passing round the drums, g, 
and attached to the pistons in the cylinders, p. The valves bringing the 
cylinders alternately in connexion with the vacuum and the atmosphere, 
are worked by pins upon the fly-wheels, r. PJ. 20, jig. 37, is the cylinder 
by which the vacuum and the atmosphere are made to operate the stamps. 
When the bottom of the cylinder is in connexion with the vacuum chamber, 
the pressure of the atmosphere which is admitted through the holes, a, 
drives the piston to the bottom of the cylinder and operates the stamps; 
at this juncture the atmosphere is admitted beneath the piston, which, 
together with the screw stamps, is drawn back by springs. This cylinder, 
M, is sunk in the vacuum chamber to the fillet, 1, and the cylinder is brought 
alternately in connexion with the atmosphere and the vacuum chamber by 
the two-way cock, b; the cock d is for cutting off communication between 
the vacuum chamber and any one of the stamping mills that it may be 
desired to stop. Pls. 21 and 22 exhibit specimens of the coins of the 
principal countries. Their names and approximate values will be found in 
the table of Contents. 
2. Paper Money. 
Paper money is the representative of metallic money, and derives its 
value from the supposed ability and willingness of the individual or com- 
pany by whom it is issued to redeem it in gold and silver. To avoid 
the chances of paper money being counterfeited, care is taken through the 
whole process of its manufacture to make the imitation of it as difficult as 
possible. The paper is first prepared with water marks, so that without the 
co-operation of the paper-maker himself, a perfect imitation cannot be made. 
The engraving is made as complicated as possible, to increase the difficulty 
of counterfeiting it, and lastly the bills are numbered and signed by the 
individuals issuing them, or by their representatives. Bank notes have 
usually been numbered by hand; but machines have been invented which 
print the successive numbers upon them without aid in making the changes 
in the numbers. The most ingenious of these machines is that invented by 
Bramah in London, and which arranges the numbers with such rapidity 
that it executes threefold more work than can be accomplished by an active 
penman. P7. 20, jig. 36, is a section of the machine. The numbers are 
arranged upon a series of rings, 1, which are turned by wheels, #, actuated 
by the motion of the handle, r: these numbers are brought successively 
from 1 to 99,999 or even higher, beneath the tympan, 5, in which position 
they are inked; the note is then laid upon them, and as the handle, r, 
descends, the impression is transferred from the types to the paper. The 
next number in order is then produced by the revolution of the rings as the 
handle is raised, and the same operation is repeated. 
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