Published three years after his phenomenally successful "The Coral Island", ""The Gorilla Hunters" finds Ballantyne bringing back three friends from previous novel but this time they are grown up men and instead of Pacific, the story is set somewhere in Africa. (Goodreads)
Robert Michael Ballantyne (24 April 1825 – 8 February 1894) was a Scottish author of juvenile fiction who wrote more than 100 books. He was also an accomplished artist, and exhibited some of his water-colours at the Royal Scottish Academy. (Wikipedia)