Though the chart proves fairly well the close dependence of the price of cast-iron pipe upon the price of the pig iron from which it is made, the chart is nevertheless misleading in that the first glance would indicate a much greater fluctuation in the price of pig iron than actually occurred.

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From liic 1910 Annual Report of the Heatlh Department, City of Boston

Fig. 98. Deaths in Boston of Children under Five Years of Age, under One Year, and from Five of the Principal Infectious Diseases, Expressed as a Percentage of the Total Mortality

Curve A. Deaths of children under five years of age as a percentage of

the total mortality Curve B. Deaths of children under one year as a percentage of the total

mortality Curve C. Deaths from Diphtheria, Scarlet Fever, Measles, Typhoid Fever

and Smallpox as a percentage of the total mortality Note that Curve A shows a much steeper slope than Curve C, yet Curve C