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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.
Like the typewriter, these machines were products of the second phase of the Industrial Revolution which started near the end of the 19th century (also called the Second Industrial Revolution). [1] This second phase brought to mass markets technologies like the small electric motors and the products of industrial chemistry without which the ...
2,6-di-tert-butylphenol is a precursor to more complex compounds used as antioxidants and light-protection agents for the stabilization for polymers. Of particular note is methyl-3-(3,5-di- tert -butyl-4-hydroxyphenyl)-propionate (CAS# 6386-38-5), which is formed by the Michael addition of methyl acrylate .
Because changing ink color in a mimeograph could be a laborious process, involving extensively cleaning the machine or, on newer models, replacing the drum or rollers, and then running the paper through the machine a second time, some fanzine publishers experimented with techniques for painting several colors on the pad. [19]
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.
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 ...
Architectural drawing, Canada, 1936. This is a simple process for the reproduction of any light transmitting document. Engineers and architects used to draw their designs on cartridge paper; these were then traced by hand on to tracing paper using Indian ink, which were kept to be reproduced with the cyano-copier whenever they were needed.
The Occupational Safety and Health Administration has set a permissible exposure limit at 5 ppm (22 mg/m 3) over an eight-hour time-weighted average, while the National Institute for Occupational Safety and Health recommends a limit of 2.3 ppm (10 mg/m 3).