If a peaktop method of plotting is used, numerous curves may be run across the same sheet and yet be distinct enough for identification even when all are reduced to uniform white fines on the blue print. It would be easy to name fifteen reasons why the method of plotting with peak tops is superior to the method of plotting with flat tops. The advantages of the peak-top method seem so obvious that it is believed the reader will agree to its desirability, without further argument being given here. The man who plots a curve has before him the data showing the actual value for each point plotted on the curve. If any questions arise in his mind regarding the comparative figures at difl^erent points on the curve, he can refer to the data from which the curve was plotted.

CURVES FOR THE EXECrTIVE

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The man who reads the curve, however, must ordinarily get the value of any point on the cur-^ e by referring to the scale on tlie left-hand margin of the chart. As most points on curves do not fall exactly on the horizontal co-ordinate lines, the only way in which the actual value at any point can be determined is by careful estimate of the fractional distance betVeen horizontal lines, according to the scale shown on the margin. The resulting value for the point is ordinarily more or less inaccurate, depending upon the scale to which the curve is drawn. Not, only is the reader's time taken in estimating the value for any point on the curve, but when he gets his result he is dissatisfied, for he cannot feel that the figure obtained is really accurate. There is a great advantage in showing on a chart the figures from which the curve was plotted.