Italic text is denoted by _underscores_.
Obvious typographical errors and punctuation errors have been
corrected after careful comparison with other occurrences within
the text and consultation of external sources.
All changes noted in the ERRATA (pg xvi) have been applied to the
etext.
Sometimes the currency symbol l (for libra, pounds) was used instead
of £. This has been changed to _l_ for clarity. For example, 50l is
represented as 50_l_.
More detail can be found at the end of the book.