—Retained publication information from the printed edition: this eBook
is public-domain in the country of publication.
—Relocated all image captions to be immediately under the corresponding
images, removing redundant references like ”preceding page”.
—Inverted the Timeline to better fit a vertical flow model.
—Silently corrected a few palpable typos.
—In the text versions only, text in italics is delimited by
_underscores_.