Multiple amount scales are more appropriate for rate-of-change charts than for arithmetic charts because in the former the movement of the curves is compared and not their position relative to a base.

Note: in order to take full advantage of the scale range, the verticol scole numerals usuolly printed on a chart sheet may be multiplied by any constont foctor but integers should be chosen so that the scale subdivisions will not indicate inconvenient fractions.

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Meaning of curve shapes on Rale-of-change charts

RATIO CHARTS

50.000 45,000 401000 35.000 30.000 2S.000

20.000

15,000 12.000

\0.000 9.000 6,000 7.000 6.000 5.000 4,000

3.000

2.000

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Automobile Manufacturers Association. "Automobile Facts and FiRures." 1035. SCALE .9

A. Average Life of a Car as Shown by Two Cumulative Curves.

Two cumulative curvt-s are plotted on the same logarithmic grid. The horizontal distance between the two lines thus gives the average life of the car. A cumulative curve may be shown on logarithmic scale as well as arithmetic. See 2 7 9.

Abstracts from Time Series Charts. A Manual of Design and Construction, 1938, prepared by Committee on Standards for Graphic Presentation, under procedure of American Standards Association, with The American Society of Mechanical Engineers as sponsor body.

CURVES. The plotting on rate-of-change charts requires considerable care because of the peculiar character of the logarithmic spacing. Where special grids are prepared without intermediate rulings, it is desirable to use a logarithmic plotting scale which may easily be made from printed commercial paper of the proper dimensions.