Duplicating machines were the predecessors of modern document-reproduction technology. They have now been replaced by digital duplicators, s, laser printers and photocopiers, but for many years they were the primary means of reproducing documents for limited-run distribution. The duplicator was pioneered by Thomas Edison and David Gestetner, with Gestetner dominating the market up until the late 1990s.
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). 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 office desk and transformed the nature of office work.
They were often used in schools, churches, and small organizations, where revolutionarily economical copying was in demand for the production of newsletters and worksheets. Self-publishers also used these machines to produce fanzines.
A few alternatives to hand copying were invented between the mid-17th century and the late 18th century, but none were widely adopted for business use.
In document duplication (as opposed to law enforcement and such), a polygraph is a mechanical device that moves a second pen parallel to one held by a writer, enabling the writer to make a duplicate of a document as it is written. Polygraphs appeared in the 17th century but did not become popular until 1800. John Isaac Hawkins and Charles Willson Peale patented a polygraph in the US in 1803, and beginning in 1804 Thomas Jefferson collaborated with them in working on improvements in the machine. He used a polygraph for the rest of his life. However, polygraphs were not practical for most office purposes and were never widely used in businesses.
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A photocopier (also called copier or copy machine, and formerly Xerox machine, the generic trademark) is a machine that makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Most modern photocopiers use a technology called xerography, a dry process that uses electrostatic charges on a light-sensitive photoreceptor to first attract and then transfer toner particles (a powder) onto paper in the form of an image. The toner is then fused onto the paper using heat, pressure, or a combination of both.
A mimeograph machine (often abbreviated to mimeo, sometimes called a stencil duplicator) is a low-cost duplicating machine that works by forcing ink through a stencil onto paper. The process is called mimeography, and a copy made by the process is a mimeograph. Mimeographs, along with spirit duplicators and hectographs, were common technologies for printing small quantities of a document, as in office work, classroom materials, and church bulletins. Early fanzines were printed by mimeograph because the machines and supplies were widely available and inexpensive.
The Gestetner is a type of duplicating machine named after its inventor, David Gestetner (1854–1939). During the 20th century, the term Gestetner was used as a verb—as in Gestetnering. The Gestetner company established its base in London, filing its first patent in 1879. The business grew, remaining within the control of the Gestetner family, and acquiring other businesses. In 1995, the Gestetner company was acquired by the Ricoh Corporation of Japan.
The course deals with the design of precast reinforced concrete structures, both for bridges and for buildings.
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