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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.
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.
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 .
This second phase brought to mass markets technologies like the small electric motors and the products of industrial chemistry without which the duplicating machines would not have been economical. By bringing greatly increased quantities of paperwork to daily life, the duplicating machine and the typewriter gradually changed the forms of the ...
By 1900, two primary types of mimeographs had come into use: a single-drum machine and a dual-drum machine. 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 ...
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 ...
Since that time phenol has become the chemical of choice for chemical matrixectomies performed by podiatrists. Concentrated liquid phenol can be used topically as a local anesthetic for otology procedures, such as myringotomy and tympanotomy tube placement, as an alternative to general anesthesia or other local anesthetics.
A second pair of parallelogram links maintains vertical correspondence between the two pens ("D" and "E" on diagram). These consist of two variable parallelogram frames attached at a common edge, one of which is also attached to the bridge, while the other is attached to one of the pen supports at each corner.