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.

SURFACE CHARTS CAN OFTEN BE USED SUCCESSFULLY:

1. To add emphojis to a chart which might appear weak as a line chort.

2. To emphosize "omount" as against "ratio."

3. To picture "point" data as distinguished from "period" data Isee definitions -- poge 9).

4. To show components of o total, especially a percentage distribution.

5. To present a general picture as ogoinst exoct measurement. SURFACE CHARTS NORMALLY SHOULD NOT BE USED:

1. Where accurate reading of values is desired, in the case of more than one component.

2. For coses where irregular layers will unduly distort the contours of the others aL>ove it.

3. Where chonges in the series are abrupt, causing opticol distortion of the width of the slroto.

Construction

1. LAYOUT AND DESIGN In generol, the principles and procedures ore the same as for line chorts.

2. GRIDS As o surface chart is rarely used for the accurate determinotion of values, few horizontal rulings ore necessary. They generally serve merely os bases of comparison. Surface charts ore generally more effective with relatively few vertical rulings. Minor time divisions can, in such coses, be indicated by means of stubs on the horizontal Kole.

COMPONENT PARTS SHOWN BY CURVES

A. Percentage Distribution of Three Types of Gasoline Feed in Engines fronn 1910 to 1918.

The total of the figures at the right-hand edge of the chart is 100%. as commented in 286.