This book is about one of the most attractive and tactile forms of slide rules, the pocket-watch slide rule. Although pocket-watch slide rules were not the most accurate nor easiest to use, these delightful devices were featured in makers catalogues from all parts of the world for the last century of the slide rule s life. Pocket-watch slide rules are an exquisite example of the slide rule makers art and are perhaps the most collectible type of slide rules. The Book Includes: -Descriptions of over 150 pocket-watch slide rules and variants -Full-color illustrations, detailed descriptions, and dating information -Approximately 80 makers and retailers from the UK, Europe, and the USA -Descriptions of special scales used -Coverage of seminal patents -A glossary of terms -A comprehensive bibliography