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Annual Report of the Health Department, City of Boston, 1910

Fig. 30. Comparative View of Twenty-five of the Principal Causes of Death in Boston During 1910

In the Boston report, the infectious diseases were represented by red bars. Here attention is called to the infectious diseases by using solid black bars in contrast with bars shown only in outline

"Railroad Operating Costs," Suffern & Son, New York

Fig. 31. Increase is Here Shown to the Right of the Zero Line and Decrease to the Left of the Zero Line. A Heavier Zero Line and Arrows Pointing Right and Left from it Would Improve This Chart

be in contrast. In Fig. 31 an example of the contrast of increases and decreases is given, increases being shown to the right of the zero line and decreases shown to the left of the zero line. This right-and-left arrangement of increases and decreases is fairly well known and is so convenient that it should be more widely used. The actual figures from which each of the horizontal bars is drawn can be shown on the chart even if the horizontal bars are drawn to the left of the zero line. The figures can be placed on the left-hand margin of the chart, immediately between the title for each bar and the end of the bar, in a manner similar to that shown in Fig. 27. Since the zero line must be near the center of the chart, rather than at the left-hand edge, when the right-and-left arrangement is used, it