Page:Graphic methods for presenting facts (1914).djvu/275

 line as in the bottom curve than by the ragged series of steps shown in the upper curve.

Fig. 202. Total Sales of the "Metropolis" Branch House of the "R.S.T." Automobile Company for Three Years

These two curves are plotted from exactly the same figures. The upper curve is drawn by the method still used by some railroads, but generally going out of use. The lower curve is plotted by a simpler method which should be universally used

Another disadvantage of the method of steps with flat tops as compared with the method using slanting lines and peak tops, is seen when two or more curves are so drawn that they intersect on the same sheet of co-ordinate paper. Curves plotted with peak tops can be drawn very close together and yet be fairly distinct from each other, as will be noticed in many of the illustrations in this book. If, however, two curves with flat tops like those shown in the upper portion of Fig. 202 are plotted in such manner that they intersect each other, the re