there were conjectural stages when makers of maps, having no certain data, but feeling sure that the blank southern hemisphere ought to be filled up somehow, exercised a vagrant fancy and satisfied a long-felt want by decorating their drawings with representations of a Terra Incognita having not even a casual resemblance to the reality.
The process presents few points of resemblance to that by which the discovery of America was accomplished. Almost as soon as Europe came into touch with the western hemisphere, discovery was pursued with unflagging energy, until its whole extent and contour were substantially known. Within fifty years after Columbus led the way across the Atlantic (1492), North and South America were laid down with something approaching precision; and Gerard Mercator's map of 1541 presented the greater part of the continent with the name fairly inscribed upon it. There were, it is true, some errors and some gaps, especially on the west coast, which left work for navigators to do. But the essential point is that in less than half a century Europe had practically comprehended America as an addition to the known world. There was but a brief twilight interval between nescience and knowledge. How different was the case with Australia! Three hundred years after the date of Columbus' first voyage, the mere outline of this continent had not been wholly mapped.
During the middle ages, when ingenious men exercised infinite subtlety in speculation, and wrote large Latin folios to prove each other wrong in matters about which neither party knew anything at all, there was much dissertation about the possibility of antipodes. Bishops and saints waxed eloquent upon the theme. The difficulty of conceiving of lands where people walked about with their heads hanging downwards, and their
