National Geographic : 1943 Jan
Through Such Lenses Pass the Most Beautiful Girls in the World A Bausch and Lomb technician measures thickness and spacing of four to eight parts for completed motion picture projection lenses (left) to within two thousandths of an inch. Each part of a lens removes some distortion; some lenses are more highly corrected than the human eye. Eight Months to Make; aFew Seconds toSmash For optical glass pots, choiceclays from six different States first were ground into fine dust, then a magneticseparator extracted the iron. Clays aremixed like dough and aged before molding. The chunks ofglass aremade into blanks for lenses of telescopes, microscopes, range finders, etc. (page 38).