Noel B. Gerson--who needs no introduction--has rolled up his sleeves and written a biography of Edward John Trelawny, a 19th-century adventurer and romanticizer. Trelawny's name was famous and infamous during much of his long life (1792-1881), usually under the soubriquet ""the friend of Shelley,"" but also as the author of three books. The last two are slight affairs, recounting and exaggerating his closeness to the poets Byron and Shelley. His first, brought out after their deaths--with assistance in grammar and punctuation from Mary Shelley--was titled ""Adventures of a Younger Son,"" and its truthfulness, from the date of its publication up until this year (see also the book by William St. Clair, below) has been hotly questioned. Because Trelawny described himself as such a blackguard, many people, including Gerson, judge him truthful. It is demonstrably true that he had a cruel childhood and was shipped by his wealthy Cornish father into the Navy at the then not uncommon age of twelve. It is true that he turned up in Switzerland and Italy in 1822 in time to become a member of the Byron-Shelley circle, gaining acceptance by marvelous tales of his adventures. It is true that he organized and presided over the cremation of the drowned Shelley's body on the beach near Leghorn; it is alas also true that he designed the fantastically unseaworthy boat in which the poet met his death. But the facts of his absconded years, on which his whole later reputation depended, are unsubstantiated and largely in doubt. In this debunking age, it is refreshing to meet a man of faith. Gerson trusts his subject entirely, and writes with all stops out.