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 chart like Fig. 174 so that the facts which it is desired to prove may be brought out clearly. Numerous methods are available for presenting such data. There is no general rule for determining which method is the best, and judgment must be used to choose the method which is best fitted to each individual case. Note that in Fig. 174 we have a scale reading to quarters of a mile, and we also have circles prominently drawn on the map at one-mile intervals to give a clear idea of the distances involved.

Country Gentleman

Fig. 172. Dates for Planting Corn, Showing How the Season Advances in Different Parts of the United States

This illustration is similar to the well-known weather maps on which lines are drawn through all points where conditions are the same

Though an illustration in the general method of Fig. 175 is attractive, and will effectively gain the attention of the reader, the method itself has all the inherent weakness of Fig. 36, Fig. 37 and Fig. 38 in Chapter III. If the reader wishes to practice some mental gymnastics, he may try to work out the ratio between the number of cattle in Idaho and the number of cattle in Texas. Though it cannot be made certain, it is probable that the chart was drawn on

Railroad Operating Costs, Suffern & Son, New York

Fig. 173. Profile of the Pennsylvania Railroad from Jersey City to Chicago. The Tabulated Figures Below the Profile Refer to the Spaces Between the Dotted Lines

This is an example of a valuable method of presentation by which a horizontal scale much smaller than the vertical scale is used so that great distances may be represented in a small space