Ray Cummings 
Girl In The Golden Atom [EPUB ebook] 

A classic work of science fiction, this novel was one of the first to explore the world of the atom. The Girl in the Golden Atom is the story of a young chemist who finds a hidden atomic world within his mother’s wedding ring. Under a microscope, he sees within the ring a beautiful young woman sitting before a cave. Enchanted by her, he shrinks himself so that he can join her world. Having worked for Thomas Alva Edison, Ray Cummings (1887-1957) was inspired by science’s possibilities and began to write science fiction. (Goodreads)