Halftones which here appear too black have been photographed from previously printed halftones rather than from original photographs.

If the subject matter of any illustration is of special interest to the user of this book, a reading glass may be used to enlarge the detail.

Because a frame around the chart may be interpreted falsely as a zero line, or base line, the liberty has been taken to remove frames from many illustrations. Changes have also been made in lettering or other details, when necessary, for reproduction in reduced sizes.

It should be clearly understood that this book would not have been feasible except for the photo offset process of reproduction and color printing.

The use of color has been a gamble-- many of the charts here shown in color were originally black and white. It was impossible to foresee results obtained from hundreds of lay-outs sent to the printer. Changes may seem obvious in the final printed form.

Designs at the top and bottom of color pages may appear incongruous with some of the color combinations in the body of the page. Varied color designs were inserted with the thought that the user of this book might gain from our experiments and select certain effects appropriate for his own particular problem.

In order to test whether color is worth while in graphic presentation, color has here been literally splashed on. In folding printed sheets for sewing into bookbinders' signatures, every other pair of pages evolve from one side of the printed sheet of paper. Thus, if color is printed on only one side, a reader finds color on every other pair of pages in the book. In this way it is possible for the reader of this book to judge the effect of color on the varied types of charts shown in the 60 chapters simply by turning the pages two at a time.