THE HORSE'S MOUTH (311 pp.)Joyce CoryHarper ($3).
The world may be a grim place, but British Novelist Joyce Gary is not the man to learn it from. Most of his favorite characters are as much in need of reformation and social uplift, if not outright restraint behind bars, as the characters of William Hogarth. Nonetheless, give or take the cautionary ends they usually come to, they enjoy themselves tremendously. Gary's distinction is that, almost alone among contemporary authors, he works in the tradition of Henry Fielding and the old English novel. With The Horse's Mouth, which completes a trilogy, more U.S readers...