This procedure, illustrated at the right, will present the curves in their correct relationship.

5. CONTROLLING CURVE MOVEMENT. Scales should be selected which will ovoid undue emphosis of any one curve. iSo selected that the relative movement of the various curves will be comporoble. It is not permissible to enlarge the movement of one curve orbitronly while minimizing the movement of the other.)

6. WIDE SEPARATION UNDESIRABLE. Scales should be selected that will bring the curves in close enough proximity for ready comparison.

7. THE SCALE RATIO. If possible, scole intervals of one scale should be in even multiples of the intervals of the other scale so as to facilitate comparisons of relative magnitude.

8. LOCATION OF SCALE DESIGNATIONS. Normolly, it is best to designate one scale at the left and the other ot the right.

9. ALTERNATIVE METHOD OF PRESENTATION. The difficulties of multiple scale presentation may be avoided by converting both series to a common base leg., index numbers, per cent of overage for period, etc.).

CURVE PAHERN

1. Curve patterns should be so selected that the curves can be distinguished readily from each other.

2. In general, the simplest patterns ore most effective and most economical.

3. In selecting curve patterns, it Is well to bear In mind the drafting difficulties and disturbing optical effects of complicated patterns.

COMPARISONS WITH TWO CURVES

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