Pins having red letters on a black background cannot be used for photographing, as the red letters would photograph black and disappear entirely, leaving a solid black circle instead of a circle with figures. Since pins with a black background and white figures are not commonly obtainable, it may occasionally be necessary to use pins like No. 20 in Fig. 199 having black figures on a white background. Sometimes it may be feasible to draw an ink-line circle around each number which appears in the photograph so that the circles will be on the copy sent to the engraver who makes the zinc plate.

When pins must be used to locate agencies, stores, or other things which are usually concentrated in cities, the limitations are rigid because all pins should be located on the map immediately above the point representing the city. Crowded pins usually have to be spread horizontally over a wide area, and when so spread out it is impossible to tell which of several adjacent cities the various pins may represent. Fig. 200 depicts what was done in one case to get over this difficulty.

GRAPHIC METHODS

"Modern PMlarUliropy" , W. H. Allen, Dodd, Mead & Cu.

Fig. 200. Sources of the First 3,000 Letters of Appeal Sent to Mrs. E. H. Harriman. These 3,000 Letters Asked for $70,000,000

Eight different kinds of pins were used on this map to represent different kinds of appeals. Long pins like those seen here are apt to fall out of the map, and thus destroy the accuracy of the record. Note the area around New York shown on a larger scale at the right