Eric Archer, electronic media experimentor, has rigged up a vector art synthesizer with an oscilloscope, a digital pattern generator, and a set of identical cards called Quadrature Wavetable Oscillators, which convert digital information into analog voltages. The outputs are summed on a two-channel mix bus, with the two channels representing the X and Y coordinates in Cartesian space. The oscillations can make beautiful fine-line patterns reminiscent of the engravings on paper currency around the world.
Specialized lathes have been in use for hundreds of years to make complex patterns that are unreproduceable without directly copying them (i.e. photography or digital means). This is the historical art of guilloche (ghee-o-shay’) or Engine Turning. Remember the old 1970’s toy called Spirograph? It operates on a similar principle, producing mathematical curves called epitrochoids via revolving circular gears around each other while a stylus traces their motion. Other combinations of motion can be used, such as mounting the stylus to a rotating disc as it traverses a straight line. Watchmakers and jewelers have long used these techniques for ornamentation on their work. The famous Faberge eggs bear designs engraved by a similar technique.
Inside these sophisticated engraving machines, there are numerous settings to be made among the gears that revolve to cut the pattern. One doesn’t need many meshed revolving gears before it becomes possible to produce endless patterns that are practically impossible to replicate. Hence this technique was adopted very early by national governments to mint their paper currency, postage stamps, and other monetary certificates. The U.S. Treasury is rumored to maintain such a machine, known as a Geometric Lathe, containing ten interlocked pattern-generating discs. The settings of the discs would only be known to a select few, as this information must be guarded from the hands of counterfeiters… at least prior to the digital age we are in now.