The Popular recreator. A key to in-door and out-door amusements .. (1873)
London, New York [etc.] Cassell, Petter & Galpin · leaf 726
as should be known asHerschel s condenser, or ameniscus and crossedlens, known as Gravettsform, or, what I find togive the flattest field onthe screen, a pair ofplano-convex lenses ofequal foci, which, more-over, possess the advan-tage of being most readilyreplaceable in the cellin which the…
Amusements · Games · Sports
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