Here the data of .January, 1913, are indicated by a dot rather than by a line. The change occurring from December to .January is not easily seen. This difficulty can be easily overcome by allowing an extra space for one month as in the following illustrations

CALENDAR YEAR !|I3 °

Bureau of Railway Economics, Washington, D. C.

Fig. 204. Monthly Revenue, Expense, and Net Revenue per Mile of Line for Railroads in the United States Having a Yearly Revenue of One

258 GRAPHIC METHODS

In Fig. 205 a curve is shown drawn upon a carefully designed four-bysix-inch card form. This card is designed for the plotting of data for one year by months. Thus, the fiscal year of a business can be shown on one card. Succeeding years are entered on different cards, so that by arranging the cards chronologically variations from year to year may easily be seen. In order to avoid the difficulties pointed out for Fig. 204, and Fig. 104, thirteen vertical lines are used on this four-bysix-inch card. At the beginning of each card the last month of the previous fiscal year is repeated. In Fig. 205 the fiscal year begins in August. At the beginning of the card we repeat the line for July, so that instead of showing a dot when the August figures are plotted w^e are able to draw a line showing the change which has occurred from July to August. In general, it is good practice to use one more vertical line than there are points to be plotted, so that the last point on one curve, sheet or card may be repeated on the next curve sheet or card.