OPTICAL PROJECTION A TREATISE ON THE USE OF THE LANTERN IN EXHIBITION AND SCIENTIFIC DEMONSTRATION BY LEWIS WEIGHT AUTHOR OF ‘ LIGHT : A COUKSK OF EXPERIMENTAL OPTICS ’ WITH 213 ILLUSTRATIONS FOURTH EDITION FIFTH IMPRESSION REVISED BY RUSSELL S. WRIGHT LONGMANS, GBEEN, AND CO. 39 PATERNOSTER ROW, LONDON NEW YORK AND BOMBAY 1906 All ri ahts reserved