These volumes are not a reference in the ordinary sense. They have been designed, instead, to give the layman an understanding of "how things work," from the simplest mechanical functions of modern life to the most basic scientific principles and complex industrial processes that affect our well-being. The result is, we believe, a unique series - a graphic and original introduction to the modern world of technology. Here you will find the answer to the question posed by the inquisitive child who wants to know how a vacuum cleaner or refrigerator works, or by you yourself, puzzled by the complexities of lasers or the secrets of Polaroid color photography. The various subjects are shown in the list of contents, overleaf, and may prove useful for cross-reference purposes. In addition, there is a full index at the end of each volume, in which both machines and topics are listed alphabetically.