The Sciopticon manual : explaining lantern projections in general, and the Sciopticon apparatus in particular, including magic lantern attachments, experiments, novelties, colored and photo-transparencies, mechanical movements, etc. (1877)
Marcy, L. J. (Lorenzo J.) · Philadelphia : J.A. Moore · leaf 25
llel rays, or principal focus. A real pencil is composed of i nnumerable rays, and such pencils from innumerable points in the object meet and cross at the lens on their way to cor- responding points in the image, and wonderful to tell, no one is switched from the track for another, and there are… … Fig. 6. in order to meet the axial rays at ft, and so it is seen that the margin of the lens G J) has a greater refracting angle than the more central portions. But the trouble is, the refracting at the margin is overdone, so that the rays d d meet the axial ray at/8 instead of at/r Hence if a…
Lantern projection · Slides (Photography)
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
