Page:Graphic methods for presenting facts (1914).djvu/352

 pencil because blue does not photograph easily and has such a small effect on a photographic plate that it does not spoil the copy for making a good zinc plate. In order to make the zinc plate from which Fig. 233 was actually printed, a red pencil was used for the bottom portion of the illustration referring to Ben Day work. Red photographs as black, and a zinc plate was obtained which shows the marking such as would be used with a blue pencil when Ben Day work is ordered from an engraver. Ben Day work has been used on a great many illustrations in this book, and it is believed that the reader will have no difficulty in distinguishing the cuts with Ben Day work from those cuts for which hand shading was used.

Fig. 233. Copy from Which a Zinc Plate Is to Be Made with Ben Day Mechanical Shading

This is the copy from which the plate for Fig. 1 was made. The areas to receive the Ben Day work are designated by arrows and numbers naming the particular kind of shading desired. Sample books give a wide choice of shadings. The markings on the face of the copy regarding the Ben Day work are made with blue pencil, since blue does not photograph dark enough to affect the line engraving