. The street railway review . n the radial line nearest to P in Fig. 29. If the proportion of coal is 150 per cent, or as too to rjo, theline can be Irjcated by taking points on the scales in that pro-portion, as 30 and 30, and the points of intersection found. In the same manner any number of radial lines can be located. Itwill be observed that along the horizontal line drawn from 20 Pthe spaces are equal for equal percentages, that is, the distancefrom 50 to 100 is the same as from too to 150. Therefore the finerdivisions can be made simply by marking off equal intermediatespaces for the val
. The street railway review . n the radial line nearest to P in Fig. 29. If the proportion of coal is 150 per cent, or as too to rjo, theline can be Irjcated by taking points on the scales in that pro-portion, as 30 and 30, and the points of intersection found. In the same manner any number of radial lines can be located. Itwill be observed that along the horizontal line drawn from 20 Pthe spaces are equal for equal percentages, that is, the distancefrom 50 to 100 is the same as from too to 150. Therefore the finerdivisions can be made simply by marking off equal intermediatespaces for the values between those first determined. Where thiscannot be done along the lower line, as indicated by broken linesin Fig. 29, for 200 and 300 per cent a similar construction can beused along a horizontal from 10 P, where the same principleapplies and 150 is equidistant from 100 and 200. .\ chart for prac-tical use should be drawn upon a large sheet and tlic percentagesdrawn in black M inlervals of 25 and in red at intervals of 5. /•»<» US FIG. 30. per cent up to a point where the steadily diminishing space pre-vents so fine a division. As the scale near the point A is not usedit is unnecessary to draw the radial lines as far as that point anda better appearance is secured by stopping all lines uniformly ona circle at some distance from A. The general appearance, but not the fine divisions, of a completedchart, are shown in Fig. ,io. The inctlii! of using the chart is alsoshown by dotted lines. Use of Percentage Chart. Suppose that the chart is laid off in generous proportions uponsectioned paper or with horizontal and vertical lines drawn so thatany points on the scales can be readily traced to their suppose that the radial lines arc accurately laid off to repre-sent proportions varying by 5 per cent. Then if it is reported thatfor a certain time 1,375 pounds of coal was used in producing1,050 pounds of product, consider the spaces on lines P and C as A i
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Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
