+--------------------------------------------------------------------+ | TRANSCRIBER’S NOTES | | | | Transcriptions used: italic and bold texts are transcribed between | | underscores and equal signs respectively: _text_ and =text=. Texts | | printed in small capitals are transcribed as ALL CAPITALS. | | Fractions are represented as, for example, 2-1/3 for two and one- | | third. | | | | Depending on the software used and its settings, not all characters| | may display properly. | | | | Footnotes [1], [2], etc. have been moved to the end of the text, | | before the Index. All footnotes contain credits for illustrations | | and/or text. | | | | More transcriber’s notes may be found at the end of this document. | +--------------------------------------------------------------------+ [Illustration: HOW COLOR PRINTING IS DONE A plate is made for each of the three printing colors, yellow, red and blue, as explained on page 382. First, yellow is printed, then red on the yellow, and last, blue on the yellow and red combination. Combinations of these three colors in various proportions produce all the other tints which appear in the original subject. Above are shown the separate plates and also the combined result of all three. Extreme care is necessary to make all the plates register exactly together.] THE WONDER BOOK OF KNOWLEDGE THE MARVELS OF MODERN INDUSTRY AND INVENTION THE INTERESTING STORIES OF COMMON THINGS THE MYSTERIOUS PROCESSES OF NATURE SIMPLY EXPLAINED COMPILED AND EDITED BY HENRY CHASE HILL WITH THE CO-OPERATION OF EXPERTS REPRESENTING EACH INDUSTRY Illustrated with 780 Photographs and Drawings PHILADELPHIA THE JOHN C. WINSTON COMPANY PUBLISHERS COPYRIGHT, 1921 BY L. T. MYERS COPYRIGHT, 1917-19 Preface This book is presented to those, both young and old, who wish to have a non-technical account of the history, evolution and production of some of the every-day wonders of the modern industrial age; coupled with occasional glimpses of the wonderful object-lessons afforded by nature in her constructive activities in the animal, vegetable and mineral kingdoms; and simple, understandable answers to the myriad puzzling questions arising daily in the minds of those for whom the fascination of the “Why” and “How” is always engrossing.