PHYSICS
TOWER, SMITH, TURTON,
AND
COPE
(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.)