REAR-ADMIRAL SAMUEL ELIOT MORISON, veteran American naval historian, talks about his new book on the early voyages to America in a conversation With PROFESSOR GWYN JONES of the University College of Wales, an authority on the Vikings. They discuss the Norse voyages, the great renaissance and Elizabethan discoverers such as Cabot, Frobisher and Gilbert, the map-makers and chroniclers such as Carter and Hakluyt. and those whose land was eventually overrun, the Eskimo and Red Indian,