A "'heliographic copier "'or "'heliographic duplicator "'is an apparatus used in the world of reprography for making contact prints on paper from original drawings made with that purpose on tracing paper, parchment paper or any other transparent or translucent material using different procedures.
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A "'heliographic copier "'or "'heliographic duplicator "'is an apparatus used in the world of reprography for making contact prints on paper from original drawings made with that purpose on tracing paper, parchment paper or any other transparent or translucent material using different procedures.
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All of them, until a certain size, can be achieved using a contact printer with an appropriate lamp ( ultraviolet, etc . . ) but for big engineering and architectural plans, the " heliographic copiers " used with the cyanotype and the diazotype technologies, are of the roller type, which makes them completely different from contact printers.
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After studying the work of Gustav Sp�rer, who examined old records from the different observatories archives looking for changes of the heliographic latitude of sunspots, Maunder presented a paper on Sp�rer's conclusions to the Royal Astronomical Society in 1890 and analyzed the results to show the presence of a prolonged sunspot minimum in the 17-18th century in a paper published in 1894.
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In the " argot " of engineers, architects and designers, the resulting plan copies coming from any type of " heliographic copier " no matter they were either blue or white, were traditionally called blueprints, name derived from the blue background color of the cyanotype technique, which was the previous process for obtaining blueprints, When the diazo based compounds changed the background color to white, in technical environments,-by tradition-, the name for copies of technical drawings remained Blueprint, although in English-speaking countries, it was intended, without much success, to change the name from"
