If maps must be printed in a report, a book, or a magazine, it is usually necessary, on account of the high cost of color printing, to use some arrangement of black ink for shading those areas which on a single map would ordinarily be colored by hand. Fig. 169 is a sample of what can be done without the use of color. If the drawing is made considerably larger than the finished illustration, the shading can be put on effectively by hand work. Mechanical shading by the Ben Day process, as regularly used by good engravers, gives excellent results but its use makes zinc cuts rather expensive. Many illustrations in this book are made by the Ben Day process. Anyone wishing to know more about the possibilities of this process should look up Fig. 233 or consult the engraver who is to make the line cuts.

Often the matter to be presented calls for maps of a large size, which can be obtained only at considerable

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GRAPHIC METHODS

Plains

Engineering Record

Fig. 169.

Drainage Area of the Canadian River, New Mexico

Areas of different kinds may be distinguished on maps by various classes of shading when color printing is not available