Transcriber's notes:
Footnotes were collected at the end of each essay and of the appendices for each essay.
On page [198] the formula (1/p) should probably be (1/pn).
Obvious typographical errors have been corrected. Any inconsistencies in spelling have been left.
“Notes” as used in this volume often means the same as footnotes. The Appendix to Essay I contains the "Notes" as used in that essay. In the footnotes to the Appendix to Essay I, one note refers to a note on another page which has been collected with all the other notes. The note referred to is indicated by a local note in braces.
In the footnotes for Essay VII this
“See ‘Nature,’ vol. 36, pp. 491-407.—E. B. P.”
was changed to
“See ‘Nature,’ vol. 36, pp. 491-507.—E. B. P.”
on supposition of a typo.