living undoubtedly went up between 1901 and 1906

course have to be made to

get a true comparison of the shipping of the two countries, for our purpose the thing of greatest interest is the general tendency of shipping in the two countries. This we can study fairly well from the general shape of the different curves, even though the curves cannot strictly be compared with each other in so far as total quantities are concerned.

Fig. 103 shows a convenient method for determining what fluctuations in the different months of the year are typical for any subject being studied. Instead of plotting one continuous curve by months for a long series of years to a rather small horizontal scale, a large horizontal scale is used and a separate curve is drawn for each year. The curves for different years are placed one above the other, so that any fluctuations which appear in the same months year after year

GRAPHIC METHODS

will be apparent from the similarity in the shape of the curves for the different years.

In order to use a fairly large vertical scale so as to make the fluctuations stand out clearly, it was necessary to avoid entirely the zero lines for the curves plotted in Fig. 103. The omission of the zero ^^MM Tonnage engaged in Foreign Trade lines may cause the fluctuations

C=Z1 Tonnage engaged In DomesticTrade from month to month to appear

greater than their true size would

Amounts ia thousands of tons

^