This chart shows a number of interesting items, among them the ranking of the principal nations of the world in the production of rayon. A. A Method of Ruling Logarithmic Paper.

1. When logarithmic paper with cycles of the proper height is not available, it is fairly

easy to rule paper using a cycle bigger or smaller than the space allotted. In the illustration above, a cycle from logarithmic paper is used for scale reduction.

2. A statistician's scale may be an easier method.

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STATISTICIAN'S SCALE

Keuffel & Esscr Co , New York.

6. l3t edge, 2 complete logarithmic scales, one 25 cm. long, one 4J cm. long.

2ud edge, 3 complete logarithmic scales, one 12 J cm. long, one 10 cm. long, one 6^ cm. long. 3rd edge, 30 centimeters, subdivided to millimeters. 4th edge, 12 inches subdivided to 40ths of Inches.

This scale is for the statistician.

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C. Triangular Scale, Engineer's,

div. 10, 20, 30, 40, 50, 60 parts to the inch.

Keuffel 8» Esser Co.. New York.

Chapter 42 THREE-DIMENSIONAL METHODS

EY MEANS of three-dimensional models, similar to those shown in 354, 355A, and 355B, it is possible to present three variables in the form of curves rather than the usual two. Other methods of showing three dimensions are illustrated in the isometric block diagram in 356A and in the trilinear chart in 359B.

Commonwrallh Edison Company. Chicago. Ill SCALE .6