Given this reference text, in which year was the youth novel by R.M. Ballantyne - which inspired Golding's first novel - written?

Context: Published in 1954, Lord of the Flies was Golding's first novel. The concept arose after Golding read what he deemed to be an unrealistic portrayal of stranded children in the youth novel The Coral Island: a Tale of the Pacific Ocean by R. M. Ballantyne, which includes themes of the civilising effect of Christianity and the importance of hierarchy and leadership. Golding asked his wife, Ann, if it would "be a good idea if I wrote a book about children on an island, children who behave in the way children really would behave?" As a result, the novel contains various references to The Coral Island, such as the rescuing naval officer's description of the boys' initial attempts at civilised cooperation as a "olly good show. Like the Coral Island." Golding's three central characters have also been interpreted as caricatures of Ballantyne's Coral Island protagonists.

Answer: 1857