1. Silently corrected typographical errors and variations in spelling.
2. Illustrations replaced with the text ‘[Illustration]’ or
‘[Illustration: some descriptive text]’. The illustration caption
is on the following line. Due to the instructional nature of this
text, extensive illustration descriptions have been added to this
text only version.
3. The original was printed in two column text with illustrations
sometimes spanning both columns. In order to reduce ambiguity, the
illustrations have been moved adjacent to the paragraph that refers
to them.
4. Footnotes have been renumbered.
5. Italicised words are enclosed by _underscores_.