proportionate number, voltage, and candle-power of various types of standard incandescent lamps delivered in different years by the New York Edison Co. are shown in a series of vertical bars which are all of the same length, representing 100 per cent. No statement is made or implied in regard to the total figures, which may have increased or decreased from year to year. x\ll we are interested in, in this chart, is the proportion of the different components which in their aggregate make up the bar representing 100 per cent in any year.

In Fig. 126 the total height of the chart represents 100 per cent.

New York Ediaon Company

Fig. 125. The Number, Voltage, and Candle-Power of the Different Types of Standard Incandescent Lamps Delivered by the New York Edison Company in Different Years, Shown as a Percentage of the Totals of All Lamps Delivered

The chart was drawii in four contrasting colors and was framed for a wall exhibit

COMPONENT PARTS SHOWN BY CURVES

1S30

Per

Cen^

US,

Foreign

70/

eo

lO

o

lOO

I850

I860

Fig. 126. Percentage of United States Foreign Trade Carried in American Vessels and in Foreign Vessels by Decades, 1820 to 1900

This t}T)e of chart requires a more highly educated reader than the type of chart shown in Fig. lio, but it gains by making the information stand out more clearly than possible with a series of bars

To show that the chart is absolutely limited to the height representing 100 per cent, we use a broad line for the zero line and another broad line at the top for the 100 per cent line. Instead of showing the percentages at different decades by the method of shaded bars used in Fig. 125, the vertical lines representing decades are first marked with points dividing the lines into component parts, then the points on the various lines are joined to give a curve.