A Treatise on Optics (Classic Reprint)

Excerpt from A Treatise on Optics A ne speculum is one which is perfectly flat, like a look ing a concave speculum is one which rs hollow like the msrri' e of a watch-glass; and a convex speculum is one which is round like the outside of a watch-glass. As the light which falls upon lass mirrors is intercepted by the glass before it is reflected m the uick-silvered sur face, we shall suppose all our mirrors to be ormed of polished metal, as they are in almost all 0 tion] instruments. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.