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Transcriber’s Notes

Inconsistencies in spelling, hyphenation, lay-out, the use of quote marks, diacriticals and accents, etc. have been retained.

Depending on the hard- and software used to read this document, some elements may not display as intended. The browser version of this document (available from www.gutenberg.org) gives best results, and contains larger versions of several illustrations.

The minor differences between the Table of Contents and the headings in the text have not been standardised.

Several plates have been printed with poor colour overlays, this has not been remedied.

Some double-page plates have been re-combined, but the area between the pages may not be exactly as printed in the original work.

Page 136, Professor Willis: should be Professor (William) Wallace; Professor (Robert) Willis invented other drawing tools.

Plate 26, pentagraph (2×): as printed in the source document.