Analysis of information sources in references of the Wikipedia article "History of the telescope" in English language version.
the largest telescope lens sag.
(spectacles) invention, an important step in the history of the telescope
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: ISBN / Date incompatibility (help)John Donavan Strong, a young physicist at the California Institute of Technology, was one of the first to coat a mirror with aluminum. He did it by thermal vacuum evaporation. The first mirror he aluminized, in 1932, is the earliest known example of a telescope mirror coated by this technique.