https://standardebooks.org/ebooks/edgar-rice-burroughs/beyond-thirty
Just sharing an ebook that’s free to download and own. Check your local public domain laws to verify. Enjoy!
“Lieutenant Jefferson Turck is a naval officer from Pan-America, the unified supercontinent and dominant world power of the 22nd Century. Though he is only twenty-one, he is greatly respected by the crew of the aero-submarine Coldwater.”
Enjoy. Along with Lovecraft they were my introduction to reading and so hold a special place for me, it is about time I revisited them as it has been a while!