THE MAPS REPRODUCED in this book reflect, in varying degree, the knowledge with which the early explorer set out, his hopes and expectations, and the discoveries which he made. The chart or map was originally developed as a guide to travellers along frequented routes. As the limits of the world known to Europeans were extended, the critical effort of cartographers came to be concentrated at its periphery, on the uncertain boundary between knowledge and ignorance. From the 15th century the map has been a powerful instrument in the communication of geographical ideas and experience. As a graphic document employing visual symbols it has made a more immediate impact on men's minds than the written word. This may be partly explained by the positiveness with which it presents geographical facts. The statements which it makes-on position, direction, distance, or extenthave an absolute character, in comparison with those of written texts which can more easily be qualified. At the same time, and perhaps for similar reasons, the influence of mapmakers on geographical thought has tended to be conservative rather than progressive, and maps alone are no true index to the state of knowledge in their time.
These general considerations are exemplified time and again in the history of exploration and in the maps associated with it. Many important discoveries have been made by expeditions in quest of illusory objectives laid down on their maps. 'The fictions', wrote Sir Walter Raleigh, '(or let them be called coniectures) painted in Maps, doe serue only to mis-lead such discouerers as rashly beleiue them.' In the longitudes in which he thought to find Cipangu and Cathay, Columbus made his landfalls in the West Indies and South America. French, Spanish and English explorers, seeking a waterway from the Atlantic seaboard to the Pacific, revealed the great extent of the American continent 'from sea to sea'. The west coast of Australia was 'unexpectedly and accidentally' discovered by Dutch ships eastward bound and out in their reckoning. Tasman, in search of a Southern Continent, fell in with New