Popular lectures on scientific subjects, by Hermann von Helmholtz 77725 [Subtitle: Second series with an autobiography of the author] [Author: Hermann von Helmholtz] [Translator: E. Atkinson] [Link: https://www.gutenberg.org/ebooks/77725] note: link will be active within two hours of posting.
Thanks to 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
