Red beads indicated assessed valuations on buildings, while green represented assessed valuations on land. Each bead represented a certain number of dollars and each pin represented an individual property. The wide adaptability of this material is evident.

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Chapter 23 MAPS WITH CIRCLES AND SECTOR CHARTS

THE chief advantage of placing circles and sector charts on maps is that the geographic location of the information is given. The general rules for sector charts in Chapter 9 may be followed here also.

1. A white line separating overlapping circles prevents any confusion.

2. Actual amounts and percentages for each geographic division should be given.

25,000

50,000

100,000

--

liJ

»- bJ

<

THOUSANDS

200,000 350,000 500.000

/ /^ ^ \

750.000

1.000.000

1 /^ ^ ^

2,000,000

\\ ( (^ ^ ) //

3,000,000

^^^^^ ^iJ^

4,000,000

5,000,000

DIAMETER

Two Mefhods of Making a Scale to Indicate What the Area of a Circle Represents by Measuring Its Dianneter.

Since it is difficult to determine the relative areas of circles, a very clear and concise scale should be given. The two methods above give the measurement of the diameters which would correspond to given area representations.

MAPS WITH CIRCLES AND SECTOR CHARTS

Each diac rapi

American Petroleum Institute, N. Y. C , "Petroleum Facts and Figures," 1937.

A. Gasoline Tax Rates in the United States as of Novennber I, 1937.

SCALE .7

Compare this as a method of presenting gasoline tax information with the method shown in 182A.

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