the two stories share the common concept of a giant diamond mine and the resulting need to protect the secret of its existence. however, they differ significantly in tone and plot details. fitzgerald's story does not involve balloons, nor a utopian society on krakatoa, nor fantastic mechanical inventions like those described in du bois's story. fitzgerald's story also takes a darker tone, with the mad owner of the mine having constructed a hollow in the earth to imprison the unfortunates who had discovered the mine. the story's protagonist has a sexual encounter with the daughter of the mine owner, and discovers that he faces execution.