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graphs of this type, it is necessary to use cross-ruled paper (quadrille ruled); if this cannot be secured from the local stationer, ordinary paper may be so ruled.

Graphs of this type are frequently employed in showing the trend of class rates and the relationship of one class rate to another. They are remarkably advantageous in arguments for rate readjustments. . In Fig. 42 the first-class, fourth-class, and sixth-class rates have been charted in the manner contemplated. The numbers on the left-hand side of the graph show the rate in cents per 100 pounds, and the numbers at the bottom show the various distances for which rates are established.

The scale of rates used in preparing this graph is as follows:

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812
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70. 75. 80. 85. 90. 95. 100. 110..

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The advantage of the graph plan in this instance is that it shows an obvious inconsistency by pictorially contrasting the rate of one class with that of another. In all properly adjusted scales of rates there should be a definite relationship between the rates of the lower classes and those of the first class, or whatever rate is chosen as the basis.

Method of Construction

The four steps necessary in constructing a twodimension graph are indicated in Fig. 43. In determining the lines, or curves, as they are commonly called,

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FIG. 43.—The Four Steps of Charting

dots may be inserted first in the proper square; when all the dots indicating the rates have been definitely indicated, they may be connected with lines, as in the figure.

Fig. 44 indicates a chart which was prepared as an exhibit in the case of the Atlas Portland Cement Company v. the Boston & Maine Railroad, comparing the present cement rates on the Boston & Maine with cement rates on the New York Central and on the Delaware & Hudson, and with the constructive rates on the basis of minimum shipments of 50,000 and 72,000 pounds, respectively.

The horizontal and vertical line method may also be used to indicate the topography of a given section of the country, or the elevation of various points in and near a city, as shown in Fig. 45. Here the marginal numbers represent the elevation in feet, while the figures at the top represent the distance of the destinations from the starting point.

BAR CHARTS

In a bar chart, the full length of the bar or block represents 100 per cent, and the various elements which go to make up the total are indicated by subdivisions of the bar.

If it is desired to depict the inbound and outbound tonnage of an industrial shipping concern, and if the figures obtainable indicate that the ratio is 45 per cent inbound and 55 per cent outbound, on a bar chart this would be indicated as shown in Fig. 46. If it were desired to distinguish between different classes of traffic, say, for example, between carloads and less

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CEMENT RATES ON D. & H. AND N. Y. C.
COMPARED WITH PRESENT AND CONSTRUCTIVE B. & M. RATES

CENTS PER 100 POUNDS

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FIG. 44.—A Composite Two-Dimension Graph

than carloads, the graph could be so modified as to include this information, as illustrated in Fig. 47.

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Ar or block chart is sometimes used in making kisou between one commodity and another.

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