Charles Conrad Sleffel

Charles Conrad Sleffel was an American writer and instructor best known for Working in Metals, published by Doubleday as part of The Library of Work and Play. Contemporary editions of the book describe him as having wide practical shop experience and as a metal-work instructor for 12 years at the Horace Mann School of Teachers College in New York.

His best-known book is a detailed guide to metalworking for beginners, covering tools, techniques, and projects in a clear, instructional style. That practical focus helped make his work useful both as a teaching text and as a general introduction for curious readers who wanted to learn by making things themselves.

Biographical details about Sleffel are limited in the readily available sources, though memorial records indicate he lived from 1860 to 1930. Because the record is sparse, much of his reputation today rests on the continued circulation of Working in Metals through library catalogs and public-domain editions.