(_Infallible when Imitated._)
The Medallions are raised patterns, or line-engravings, generally
representing a head, or some raised fancy patterns in genuine Bank Notes,
which look as if raised up from the paper. They are called medallions
because they are copied always from and represent the pattern upon a
medal. It is done by the Pentograph Ruling Engine, which, guided by the
medal, rules the whole pattern in _full length lines_, and the dies are
_double_ transferred to the plate, which makes the lines _black_, the same
in appearance as if the pattern was ruled directly upon the plate itself
by the engine. This work is done upon the same principle in mechanics of
“_guides_,” as shoe-lasts are turned by the “Last turning machine.” A
model last is used for a guide to the machine, which turns out of a
rough-hewn block of wood a last exactly like the model. Thus in genuine
medallion ruling there is always a medal or coin used for a “_guide_.” The
points in determining genuine medallions from imitations engraved by hand,
are, the lines in the genuine all run in one general direction; they are
always _full length lines_ across the whole pattern, the lines are all
_exactly the same size_ or caliber, they _never cross each other_. Every
undulation in the pattern on the guide or medal is copied with the most
_unerring exactness_, and articulated _distinctly_ and beautifully
correct, which is impossible to be done so perfectly by hand. In the
counterfeit the lines are apt to _break off_ in the midst of the pattern;
some lines are apt to be _coarser than others_, which gives it a scratchy
appearance. In the genuine, the lines crowd together in the parts of the
pattern that appear depressed or sunken, and spread apart more where the
pattern appears raised and looks whiter, producing the lights and shades
with the most magnificent ease and effect. In the counterfeit done by hand
the lines do not crowd and spread apart again, according to the pattern,
with such ease and effect, but the patterns appear stiff, flat, or
imperfectly raised. There is always one of two ways or alternatives in
which the hand-work imitations appear to fail. If they succeed in making
the lines full length, as they ought to be, then the pattern will
inevitably appear _flat_ in expression, imperfectly raised; but if they
succeed in making the pattern look _raised_, as it ought to be, then there
will inevitably be _broken_ or _forked lines_ all through the midst of the
pattern. It seems impossible to combine in hand-work imitations of this
extremely fine and complicated work full length lines, and at the same
time a perfectly _finished_ and _raised_ pattern, which the Pentograph
Ruling Engine always does in the highest perfection.
[Illustration: I J
_Magnified 5 to 10 times._
K
_Magnified 10 to 15 times._]
Diagrams I and J represent the appearance of counterfeit Medallions when
magnified. K represents the appearance of a genuine Medallion as magnified
10 to 15 times. _Every line is full length_, and exactly of the _same
size_. In J the lines _break off_ and _fork together_ all through the
midst of the pattern, and some lines a little _coarser_ than others,
which gives it a scratchy appearance.
Whenever there are two or more medallions in a genuine bill that pretend
to be alike, they are always exactly alike; being double-transferred from
the same original die; (see medallion heads marked ‘3’ in the steel
plate,) but two medallions cannot be made exactly alike separately by
hand. The following extract in relation to this work is quoted from the
Mechanic’s Magazine, 1835: “The Journal of the Franklin Institute for
September contains an elegant engraved portrait of Wm. Congreve, the
dramatist, executed by Wm. A. Spencer of Philadelphia, in the manner
described, and has inserted the following proofs that the invention can be
claimed for America. ‘Believing that the credit of the invention of a
machine for medal ruling is due to America, we will briefly set forth our
proofs, and then speak of the improvements which of late years the method
has undergone. The proofs to be given of the existence and state of the
machine are to be derived from the results produced by it. In 1817, by the
use of a machine which had been invented in Philadelphia, Christian
Gobrecht, die-sinker, produced an engraving upon copper, from a medal
having upon it the head of Alexander of Russia. From this engraving
impressions were taken and distributed. One of these impressions we have
seen. In 1819, Asa Spencer, now of the firm of Draper, Underwood & Co.
bank-note engravers, took with him to London a machine of the kind above
alluded to, which was designed principally for straight and waved-line
ruling. This machine was used in London during the year just mentioned,
and the mode of ruling waved lines, and of copying medals, was then
exhibited and explained by Mr. Spencer to several artists--particularly
Mr. Terrell, who took by permission a drawing of the machine, for the
purpose of having one made for his own use. Little however was done in
the way of medal ruling until about three years since, (1832,) when a
desire to apply the method to the engraving of designs for bank notes
caused it to be revived by Mr. Spencer, who bestowed great attention upon
it, and overcame the difficulties met with in the onset.’--The peculiar
construction of this machine has never been made a secret, nor has it ever
been patented, although prudential motives have required that it should
not be minutely described, and thus be placed in the hands of those by
whom its use might be perverted. The operations performed by this machine
are the ruling of parallel straight lines at any required distances apart,
either continuous or broken; ruling converging straight lines; ruling
waved lines, the waves being either similar, varying by more or less
imperceptible gradations; and medal ruling or transferring to copper the
fac-simile of a medal without injuring its surface, the waved lines
presenting a copy of the minutest parts of the medal.”