It is, however, desirable to have the bottom line either at ten or some power of ten on the vertical scale

and engineering supplies. A person doing statistical work for which paper with the logarithmic ruling is desirable may occasionally have to rule his own paper. This, however, is not an impossible task especially if one has a slide rule. The spacing of the lines can be copied from either scale of the slide rule, or it may be worked out easily to fit any

GRAPHIC METHODS

given space by dividing into tenths and hundredths and using tables of logarithms.

It is of interest to note here that the data of Fig. 121 would show as a perfectly straight line if plotted on paper having the logarithmic ruling for the vertical scale. Since the increase from year to year is uniform, on a percentage basis, the points of the curve all fall on a straight line drawn from the first point to the last point.

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