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[1] A simple, so-called "lateral" harmonograph uses two pendulums to control the movement of a pen relative to a drawing surface. One pendulum moves the pen back and forth along one axis, and the other pendulum moves the drawing surface back and forth along a perpendicular axis.
Reproduction of Jefferson's polygraph at the Smithsonian Institution One of the polygraphs used by Thomas Jefferson, a portable version. A Polygraph is a duplicating device that produces a copy of a piece of writing simultaneously with the creation of the original, using pens and ink.
The single-drum machine used a single drum for ink transfer to the stencil, and the dual-drum machine used two drums and silk-screens to transfer the ink to the stencils. The single drum (example Roneo) machine could be easily used for multi-color work by changing the drum – each of which contained ink of a different color.
The Great Phenol Plot was a clandestine effort by the German government during the early years of World War I to divert American-produced phenol from the manufacture of high explosives that supported the British war effort. It was used by the German-owned Bayer company, which could no longer import phenol from Britain, to produce aspirin.
In its chemical structure, a molecule of cresol has a methyl group substituted onto the ring of phenol. There are three forms of cresol: ortho-cresol (o-cresol), meta-cresol (m-cresol), and para-cresol (p-cresol).
In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (−O H) bonded directly to an aromatic hydrocarbon group. [1] The simplest is phenol, C 6 H 5 OH. Phenolic compounds are classified as simple phenols or polyphenols based on the number of phenol units in the ...
An Egyptian method of determining the time during the night, used from at least 600 BC, was a type of plumb-line called a merkhet. A north–south meridian was created using two merkhets aligned with Polaris, the north pole star. The time was determined by observing particular stars as they crossed the meridian. [24]
Desmond Paul Henry (1921–2004) was a Manchester University Lecturer and Reader in Philosophy (1949–82). He was one of the first British artists to experiment with machine-generated visual effects at the time of the emerging global computer art movement of the 1960s (The Cambridge Encyclopaedia 1990 p. 289; Levy 2006 pp. 178–180).