The slide rule:, by Charles N. Pickworth 75904 [Subtitle: a practical manual] [Author: Charles N. Pickworth] [Link: https://www.gutenberg.org/ebooks/75904] note: link will be active within two hours of posting. Thanks to Richard Tonsing and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive) Regards, Al