LENSES. 53 denser the medium the greater is the refraction, and that it varies also in different sorts of glass for the same size lens. We will suppose the lenses are made of crown glass, which allows the focus to be illustrated by the centre or circumference of the circle correspond- ing to the… … focus will be at the same distance as the light. * ‘Convex’ is from the Latin con , together, and velio, to carry, 1 to carry together, brought round.’ ‘Concave’ is from con, intensive, and cavus , hollow, like a cave, ‘ completely hollow. ’ If it is noticed that the hollow lens is like a cave, the…
Light · Color · Optical illusions · Optics
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
