Page:Graphic methods for presenting facts (1914).djvu/136

 The Engineering Magazine

Fig. 105. Comparison of Daily Electrical Output and Daily Coal Consumption of a Power Plant for the Same Month in Two Succeeding Years

There is a relatively small quantity of power needed on Sundays. In order to make possible a comparison of the two curves for different years the horizontal scales for days were so placed that the Sundays would coincide. With curves thus arranged, the low points caused by Christmas do not fall on the same vertical line, since Christmas is fixed by the day of the month instead of by the day of the week