Society of Glass Technology · [Sheffield] · leaf 647
and then one sideis countersunk by the forma-tion of the lenticular concavity,6. The surface of this depres-sion is finished and polished tothe usual high degree, and theminor lens, 7, is ground andfinished to the same radius ofcurvature. The two lenses areplaced in contact and sub-jected to a… … Fig. 180. MACHINERY FOR THE WORKING OF GLASS. 217 that happens to be entrained between the two lenses. Such dis-placed air is not trapped, but is permitted to escape freelythrough the hole, 5; this escape of air may be facilitated byinverting the two lenses and having the minor lens below themajor…
Glass
Internet Archive · Gerstein Library, University of Toronto · Public Domain Mark 1.0. Free to use for anything.
