(_Infallible when imitated._)
The “Geometric Lathe” is a very perfect and costly Engraving Engine, which
produces very fine and beautiful ornamental patterns of geometric circles
of such complication, uniformity, and exquisite perfection, that it cannot
possibly be imitated in any manner. It engraves or turns the circular or
oval patterns on the dies, on which the figures representing the
denomination of the note are placed. A sketch of this engine is quoted
from “_Nicholson’s Operative Mechanic_.”
“One of the most important securities to the paper currency of nearly the
whole commercial world at the present time arises from the invention of
transferring engravings, and the work produced by the Geometric Lathe,
invented by Mr. ASA SPENCER, while a resident of New London, in the State
of Connecticut. The application of this Lathe-work for the security of
Bank Notes was first made by Messrs. FAIRMAN, DRAPER & CO., of
Philadelphia, in 1816, and from its great beauty and difficulty of
imitation, Mr. Spencer was induced to repair to England in 1819, for the
purpose of securing the paper currency of that country. As had been
expected, this work was put to the severest test which the combined talent
of its great metropolis could invent, and having passed this trial in a
very satisfactory manner, it was subsequently adopted very generally by
the Banks and Bankers of England and Scotland.
“The Geometric Lathe differs materially from any other _turning_ engine
hitherto invented. The only one which has any similarity in the work
produced, is the “Rose Engine;” but that is only capable of copying
patterns previously made upon guides, while the Geometric Lathe forms its
own patterns, which are all _originals_, and as various and unlimited as
the ‘Kaleidoscope.’…
“The impossibility of successfully imitating this work by any process of
hand-work within the reach of the whole combined talent of counterfeiters
will not be doubted when the severe test to which it has been submitted is
recollected: and even supposing any combination of counterfeiters to be in
possession of the different machines and appendages necessary to effect
their object, they would soon find that the time which would be required
to learn the use of these implements in secret, could be more profitably
employed in any honest occupation.”
The patterns produced by the Geometric Lathe are concentric, eccentric, or
geometric circles, radiating from a common centre, and beautifully
interwoven into each other, forming a perfectly regular and uniform
‘fancy’ pattern, so exactly true and uniform in its radiations, that there
never is the slightest possible irregularity or imperfection. It is
because the patterns are of such exquisite beauty and perfection, and at
the same time extremely fine and complicated, that it is utterly
impossible to imitate it by hand or by any process whatever. The Geometric
Lathe does not engrave the patterns immediately upon the plate itself, but
the patterns are transferred to the plate from roller dies or cylinders,
generally in two places, as a majority of bills contain two dies alike,
sometimes four, one in each corner. Being single-transferred the patterns
are reversed, and are then _white_ circles or lines upon a _black ground_.
Of course whenever there are two or four dies that pretend to be alike in
a genuine bill, they will all be exactly alike, being all transferred from
the same one die. See the two transfers of the die in the steel plate
containing the ‘3.’ In imitations of Lathe-work in counterfeit bills there
will be a failure in two ways: first, in imitating regularity of the
pattern, which is attempted to be done by hand, and also it is cut
directly on the plate instead of transferring, so that what in the genuine
is black _spaces_, is _engraved_ black in the counterfeits, leaving white
spaces and black dots, resembling cobble-stones--the white spaces between
which made to resemble white lines, while it can easily be seen that it is
only irregular black _dots_ and scratches instead of white lines or
geometric circles. Secondly, a failure in getting two dies exactly alike
in the same bill--that is, where they pretend to be alike. If done by hand
there cannot be two fine and complicated patterns made _exactly alike_;
but in the genuine, where the pattern on one die or cylinder is rolled or
transferred in two or more places, they will all of course be exactly
alike. This same work is to be seen on the backs of watches, called
“Engine Turning.”
[Illustration: A B
_Magnified 5 to 10 times._