The whys and wherefores of navigation, by Gershom Bradford 73652 [Author: Gershom Bradford] [Link: https://www.gutenberg.org/ebooks/73652] note: link will be active within two hours of posting. Thanks to Carol Brown, Chris Curnow 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