A loose but commonly accepted term for a kind of prose narrative addressed for the most part to boys, in which a hero or group of heroes engages in exotic and perilous exploration. It is a masculinized variety of romance, one in which the erotic and religious dimensions common to other types are subordinated to or completely replaced by an emphasis on vigorous outdoor activity and the practical arts of survival amid unexpected dangers, along with a cultivation of such virtues as courage and loyalty. Marvellous events may be witnessed, but usually within a context provided by modern scientific knowledge. The genre flourished in the later 19th century, its most influential master being the French writer Jules Verne, whose series of eighteen Voyages extraordinaires include Voyage au centre de la terre (Journey to the Centre of the Earth, 1864) and Vingt mille lieues sous les mers (Twenty Thousand Leagues under the Sea, 1870). Popular examples in English included H. Rider Haggard's King Solomon's Mines (1886), Arthur Conan Doyle's The Lost World (1912), and P. C. Wren's Beau Geste (1924). Partial overlapping with science fiction, as in Verne's case, or with the thriller and other popular forms, is sometimes found.