Graphic Methods for Presenting Facts
The drop in the export line from 1860 to 1870 was almost one-half, while the drop in the import line for the same period was much less than one-half, even though the import line does show the greater slope downward.
In Fig. 72 we have an example of what not to do in charting. The main effect of the circles is to give one a headache without permitting any accurate comparison between the years. The eye does not easily see each circle as an area. The tendency is to see only rings
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Fig. 71.
Cotton Goods Production, Import and Export for the United States
These curves are plotted frcm the data of Fig. 70, and show the information in much clearer form
GRAPHIC METHODS
between the lines of the circles, rather than the whole area included inside of each circle line.
Fig. 73 gives the data of Fig. 72 in curve form. The heavy solid line curve shows the changes from decade to decade as they could never be interpreted from either the actual figures or the circles of Fig. 72. The tremendous increase in the world's commerce between 1900 and 1910 is of very great interest, showing the effect which better means of communication have brought about as a result of the splendid increase in scientific and engineering knowledge.