Another advantage of half-tones is that different colors of pin heads are represented in the half-tone by different shades of gray, as can be seen in Fig. 191. On the left half of Fig. 191, fourteen different colors of glass-head map pins were used. The photograph Avas not retouched in any way. Fig. 191 thus represents about what can be expected of different colored pin heads for contrast in half-tone illustration. Note the high lights which give white spots on the circles of the darker pin heads. It is spots like these which should be retouched by hand on any photograph from which a line cut is to be made.

Tacks and pins have been used on maps to locate agencies, salesmen, customers, etc., more than for any other one purpose. The various possibilities in applying tacks and pins to sales-department work cannot be thoroughly covered here, but if a few general methods are known, each sales manager can work out for himself the pin scheme which best suits his own conditions.

Fig. 191 was photographed, without any retouching, direct from a section of the United States Geological Survey topographical maps. These contour maps, having a scale of about one inch to the mile, may be obtained from the Geological Survey at Washington, for most of these sections of the country which are thickly settled. The maps are very low in cost and yet are remarkably accurate. Fig. 191 was

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MAPS AND PINS 237

purposely photographed at an angle of about 45 degrees. As the upper part of the illustration is out of focus because of the angle, the illustration does not do justice to the Government maps. Another reason why the map does not come out clearly is that brown ink is used to print the contour lines and these lines accordingly show only faintly in the half-tone.