It does not wrinkle paper and may be used for a temporary joining, as well as for a permanent one.

Transparent materials may be used to great advantage in comparing curves, bars, or other types of graphic charts. The charts are drawn directly on the transparent material. When placed over each other, a clear comparison is possible.

SOURCES OF TRANSPARENT MATERIALS: Celluloid Corporation, Newark, New Jersey. E. I. Dupont De Nemours &> Company, New York City. Eastman Kodak Company, Rochester, New York. Monsanto Chemical Co., St. Louis, Missouri.

Eugene Dietzgen Co., New York City.

A. Ratio or Logarithmic Chart Paper.

Logarithm ic paper is obtainable with the log scale in both horizontal and vertical rulings or with the log along only the ordinate.

Log paper is obtainable in various sizes and with various cycles or decks.

Kcuffcl & Esser Co.. New York City. SCALE .6

B. Percentage Protractor.

The percentage protractor is of particular value to anyone making graphic charts, since it can be used in the construction and measurement of sector charts and similar graphs.

SUGGESTIONS FOR MAKING A CHART

A. Triangles, T-Square, and French Curve.

1. The triangle on the left is 30 x 60 degree, while the one on the right is a 45 degree triangle.

2. French curves are available in a great

many shapes and forms. The one shown here is one of the simplest.

3. These drawing instruments arc part of

the equipment for a standard drawing board.

Eugene Dietzgen Co., New York City. SCALE .5