It may be thought, perhaps, that exploration must be comparatively easy today. Less laborious no doubt it is in some details when Mandeville and Magellan travelled. But there are difficulties enough remaining to leave the romance of exploration untouched. Every explorer carries his life in his hand, however fine may be his outfit. Within the limits of this volume it is impossible even to notice all the modern explorers who have a claim on our admiration. - Summary adapted from the introduction