The Transcriber copied the index from Volume IV. It was not checked for proper alphabetization or correct page references. Most of the references are to pages in the other three volumes of this series; all four volumes are available at no charge at Project Gutenberg:
Volume I: [https://www.gutenberg.org/ebooks/71794]
Volume II: [https://www.gutenberg.org/ebooks/71795]
Volume III: [https://www.gutenberg.org/ebooks/71796]
Volume IV: [https://www.gutenberg.org/ebooks/71797]
In the original book, the index entries for "Biddle, Captain Nicholas" referring to Volume II. actually refer to his nephew, "Biddle, James", and some of those are in Volume III. In this ebook, those entries have been corrected, but the index may contain other errors.