Laurence, Lionel · London, School of Optics · leaf 136
urned over so that the other face becomes thefront, the axis, is then at 120° (Fig. 129). If the one position were 5°, theother would be 175°. It is only when the axis is vertical or horizontal thatno change occurs on reversing the lens. When the one inclination is 45° or at135°, turning the lens… … the horizontal, or to the right or to the left of the vertical, and assigningits position accordingly; or it is done simply by deducting the numericalposition of the axis from 180°. Thus, suppose the axis is at 60°, this is 30°to the right of the vertical; on turning the lens the axis is at 90° +…
Optics
Internet Archive · Gerstein Library, University of Toronto · Public Domain Mark 1.0. Free to use for anything.
