In Fig. 66 the attempt to give a spectacular scheme of presentation seems to have overshadowed everything else in the mind of the illustrator. Though a striking architectural design has undoubtedly been obtained, the chart means nothing, for it is impossible of interpretation. No scale has been used in either the horizontal or the vertical direction, as can be seen by comparing the figures on the block for 1830 with the figures on the block for 1840. Even if some scale had been used in making up this chart, the general scheme is such that the reader would hopelessly flounder in trying to reach an accurate interpretation.

Fig. 67 puts the data given in Fig. 66 in the form of horizontal bars. Note that the values which the bars represent are given inside of the bars, for reference purposes. In order to make the shape of each bar stand out distinctly, gray dots were used which permit the figures representing the values to be read through the shading. This is an interesting attempt, but it is not satisfactory as a general scheme. Though Fig. 67 gives the data much more clearly and far more accurately than Fig. 66, the method is not satisfactory because it is difficult for the eye to follow the ends of the different bars in order to judge the increase made from decade to decade. The best method

GRAPHIC METHODS

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The Philadelphia Commercial Museum

Fig. 66. Commerce of the United States since 1830. The Sum of Annual Exports and Imports. Values are given in Millions of Dollars