In all requests, include “Zip Code” in return address. Printed in the United States of America USAEC Division of Technical Infection Extension, Oak Ridge, Tennessee Transcriber’s Notes --Retained publication information from the printed edition: this eBook is public-domain in the country of publication. --In the text versions only, text in italics is delimited by _underscores_. --In the text versions only, superscript text is preceded by ^caret. --In the text versions only, subscript text is preceded by _underscore. End of the Project Gutenberg EBook of Nuclear Clocks, by Henry Faul