Page:Graphic methods for presenting facts (1914).djvu/61

 In Fig. 42 the idea is brought out that the railroads are now handling more freight. The drawing, however, should be reversed so as to have the two locomotives one above the other facing to the left, with the additional cars at the right-hand end. It would also be better if the dates for the two years and the figures representing tons had been placed at the extreme left in the manner shown in Fig. 41.

In Fig. 43, the two locomotives are placed neck and neck, but the whole chart reads backwards in that it reads to the left instead of to the right. Turn the page over and hold it up to the light. Through the back of the paper, the arrangement of the cars appears from left to right as it should.

Fig. 44. Yearly Cotton Production and Export of the United States. The Figures with the Arrows Show the Number of Millions of Bales and also the Value in Millions of Dollars

If horizontal bars are used to represent years, the earliest year should be shown at the top as seen here

No data are given in Fig. 43, and it is impossible to tell whether the comparison between 1901 and 1912 should be based on the ratios of the whole length, including engines, or whether it should be based on the lengths for cars only. A ratio without the engines would be much larger than with engines. This chart is accordingly unreliable. The difficulty in regard to engines being included in the drawing could be entirely overcome if the freight cars were made in solid black, with the engines shown in outline only, so that the eye could judge the ratio between the solid black bars representing freight cars without including the outline drawings of the engines.

Often in charting information like that given in Fig. 44, vertical bars instead of horizontal bars are used. However, the figures given in Fig. 44 in conjunction with the bars make it desirable that the bars should here be horizontal in order that the figures may be read easily.