Water lining.—The use of water lining on black and white maps should be limited to maps on which the water areas are not readily distinguishable from the land areas. In rough drawings that are to serve only as copy for engravers a flat color may be used for water areas and its conversion into water lines specified. In base maps to be reproduced in three colors a light-blue tint may be used in lieu of water lining, and it can be printed either flat or in a fine ruling transferred to the stone that is to print the drainage. The engraving of water lines is expensive, and the flat blue color should generally be preferred.
Water lining usually consists of 30 to 45 lines on engraved or large maps, but on small maps and sketch maps the number may be reduced as desired. Care should be taken that the lines are as nearly parallel as they can be made freehand and of even weight or thickness. The first three to six lines outside the coast line should be somewhat closer together than those farther out and should conform closely to the coast line, but the spacing between the lines should increase and the lines should become almost imperceptibly less conformable to the coast line as they reach their outer limit, the last three to six being made with the greatest care and refinement. Water-lined maps that are to be reproduced by photographic processes should be drawn at least twice publication size. The reduction will bring the lines closer together, and the reproduction will show a more refined effect than could possibly be produced by the most skillful drawing.
Good examples of water lining, such as are shown on the topographic atlas sheets of the Survey, should be studied by draftsmen before they undertake such work.
U. S. GEOLOGICAL SURVEY
PREPARATION OF ILLUSTRATIONS PLATE IV
SYMBOLS USED ON BASE MAPS