TOWER, SMITH, TURTON, (See p.441) Three-color Printing Y. Yellow impression; negative made through a blue-violet filter. R. Crimson impression; negative made through a green filter. RY. Crimson on yellow. B. Blue impression; negative made through a red filter. YRB. Yellow, crimson, and blue combined; the final product. (Courtesy of Phototype Engraving Co., Philadelphia.) PHYSICSBY WILLIS E. TOWER, M. SCI. (Univ. of Illinois) CHARLES H. SMITH, M. E. (Cornell) CHARLES M. TURTON, A. M. (Syracuse) IN COLLABORATION WITH THOMAS D. COPE, Ph.D. (Pennsylvania) BASED UPON WITH 7 PLATES AND 448 OTHER ILLUSTRATIONS PHILADELPHIA Copyright, 1920, by P. Blakiston's Son & Co. |