Transcriber's Notes

Obvious typographical errors have been silently corrected. Variations

in hyphenation have been standardised but all other spelling and

punctuation remains unchanged.

Italics are represented thus _italic_. The majority of authors and

titles in the catalogue are in bold text but, for the sake of clarity,

this has not been marked up. The complex and cramped layout of the book

catalogue has been simplified.

On the various forces of nature and their relations to each other · 第 187 / 187 题