The use of engineering dimension lines in Fig. 133 is of interest, for the dimension lines add considerably to the clearness of the drawing. In the center of the chart the vertical dimension lines on both sides of the names for each area show distinctly that the chart must be read on the basis of the vertical distance between the two curves on either side of any area. At the right- and left-hand edges of the chart the over-all dimension lines show the reader at once how to read the chart so as to include all the various components entering into any total which may be under consideration. The use of dimension lines should be thoroughly understood by everyone drawing charts or plotting curves, and by everyone having graphic presentations to read. Dimension lines may add much to the clearness of a chart without being in themselves unduly conspicuous.
