Frank Reade, Jr.'s Desert Explorer; or, The Underground City of the Sahara
From Author Wars - https://authorwars.com/books/frank-reade-jrs-desert-explorer-or-the-underground-city-of-the-sahara-2432314.html
From Author Wars - https://authorwars.com/books/frank-reade-jrs-desert-explorer-or-the-underground-city-of-the-sahara-2432314.html