The Table of Contents does not mention the “Table of Useful Astronomical Facts”, which begins on page 391, immediately preceding the Index.

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

Simple typographical errors were corrected; unbalanced quotation marks were remedied when the change was obvious, and otherwise left unbalanced.

Illustrations in this eBook have been positioned between paragraphs and outside quotations. In versions of this eBook that support hyperlinks, the page references in the List of Illustrations lead to the corresponding illustrations.

The index was not checked for proper alphabetization or correct page references.

Page 208: The reference to page 124 should be to page 128.