Punctuation, hyphenation, and spelling were made consistent when a predominant preference was found in this book; otherwise they were not changed.

Simple typographical errors were corrected; occasional unbalanced quotation marks retained.

Ambiguous hyphens at the ends of lines were retained.

Illustrations were printed mid-paragraph but have been moved between paragraphs, usually near to text that references them.

Footnotes have been collected and repositioned just before the Index.

Some in-line paragraph headings are in boldface and some are in italics; this emphasis has been retained.

Index not checked for proper alphabetization or correct page references, but a reference to page 274 was a typographical error and has been changed to 174.

Page 155: Text refers to c c' in Figs.38–39, but neither figure appears to contain a c' label.