Wheatstone and Cooke telegraphs, 130. Wimshurst machine, 12. Wireless telegraphy and telephony, 179, 203, 270, 280. Wires, telegraph, 141. X-rays, 231, 242. MORRISON & GIBB LIMITED, EDINBURGH 5/15 2½ Transcriber’s Notes Punctuation, hyphenation, and spelling were made consistent when a predominant preference was found in the original book; otherwise they were not changed. Simple typographical errors were corrected; unbalanced quotation marks were remedied when the change was obvious, and otherwise left unbalanced. Illustrations in this eBook have been positioned between paragraphs and outside quotations. In versions of this eBook that support hyperlinks, the page references in the List of Plates lead to the corresponding illustrations. (There is no list of the other illustrations.) Plate VIII., “Typical Electric Locomotives,” listed as being on page 90, was not in the original book and therefore not in this ebook. The index was not checked for proper alphabetization or correct page references.