It is really a calamity that curves are not more widely understood. Ad vertising men are now frequently unable to convince people of their argument simply because they have no language by means of which figures can be made interesting or even intelligible when expressed in an advertisement of hmited size. The author ventures to predict that it will be only a very few years until curves are so widely understood and used that they may be presented advantageously in any high-grade advertising pages.

It would be almost impossible to give a clear idea of the flood indicated in Fig. 76 if only columns of figures were used. With the curve it can be seen clearly that the stream rose very rapidly and subsided rapidly, so that the stream was down almost to normal level within forty-eight hours after the beginning of the flood. This curve was probably plotted from flood-gauge readings taken once an

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Fig. 74. Prices of Cement, per Barrel, in Bulk, at the Mill, from 1880 to 1910

Columns of printed figures or a series of vertical bars could not portray this information as vividly as it is brought out by the curve shown above