Page:Graphic methods for presenting facts (1914).djvu/296

 Fig. 212. Total Payroll of the "A.B.C." Automobile Plant for the Year 1911. Weekly Figures Are Given to the Nearest Dollar Only. Pay Weeks End on Thursday

other sources of information. This is straight clerical work and may be done with a pen on one card after another with great rapidity. Ordinary liquid drawing ink is the best for the figures, as the opaqueness of the drawing ink gives better blue prints than are obtainable from writing ink. This is often partly transparent and prints pale blue instead of clear white. After the figures have been entered on all the cards, the cards are taken rapidly one by one and a sharp lead-pencil is used to mark on the proper vertical line a point which, according to the vertical scale, corresponds with the newly recorded figures in the upper margin. When all the curve points have been located by lead-pencil marks on the curve cards, a drawing pen is used to draw the line on each card to show the change that has occurred since the previous point was plotted. As the new point has already been indicated in each case by the lead-pencil