Such charts sent to many zinc engravers are returned with the statement that it is impossible to make a line cut from green-ink copy. The statement is made in most cases by the engraver without even attempting to make the cut. There is no difficulty in making excellent zinc cuts from copy using the ordinary green ink, and many of the cuts in this book have been so made, as, for instance, Fig. 156, Fig. 207, and Fig. 215.

GENERAL METHODS 331

Of course, when line cuts are made from charts having a green-ink background, the printed illustration shows both the black and greenink lines as black, and there is no distinction between the different lines. On this account, it is necessary for the person ordering the charts made from paper having green-ink lines to make certain that the main features of the chart stand out with prominent broad lines, so that there may certainly be a contrast in the width of the Ijnes when printed, to make up for the contrast obtained in the original drawing by the difference in color of the two inks used.

Color printing is not yet ordinarily available unless a very large number of copies are to be made. In order to make areas stand out in contrast, different kinds of cross-hatching put on by hand ruling have been used very commonly. One trouble with the hand ruling is that it lacks uniformity unless done with very great care and to a scale considerably larger than the finished illustration, so that there may be enough photographic reduction to eliminate many of the defects which would otherwise appear. It is not widely known that there is a method available in the form of Ben Day mechanical shading, which is far superior to cross-hatching for line-plate work.