to the east, which, in the Latinised versions of his astronomical work, was termed “terra australis incognita,” or “the unknown south land.”  As, by his error with regard to the breadth of the earth, Ptolemy led to Columbus; so, by his mistaken notions as to the “great south land,” he prepared the way for the discoveries of Captain Cook.  But notwithstanding these errors, which were due partly to the roughness of the materials which he had to deal with, and partly to scientific caution, Ptolemy’s work is one of the great monuments of human industry and knowledge.  For the Old World it remained the basis of all geographical knowledge up to the beginning of the last century, just as his astronomical work was only finally abolished by the work of Newton.  Ptolemy has thus the rare distinction of being the greatest authority on two important departments of human knowledge—­astronomy and geography—­for over fifteen hundred years.  Into the details of his description of the world it is unnecessary to go.  The map will indicate how near he came to the main outlines of the Mediterranean, of Northwest Europe, of Arabia, and of the Black Sea.  Beyond these regions he could only depend upon the rough indications and guesses of untutored merchants.  But it is worth while referring to his method of determining latitude, as it was followed up by most succeeding geographers.  Between the equator and the most northerly point known to him, he divides up the earth into horizontal strips, called by him “climates,” and determined by the average length of the longest day in each.  This is a very rough method of determining latitude, but it was probably, in most cases, all that Ptolemy had to depend upon, since the measurement of angles would be a rare accomplishment even in modern times, and would only exist among a few mathematicians and astronomers in Ptolemy’s days.  With him the history of geographical knowledge and discovery in the ancient world closes.

In this chapter I have roughly given the names and exploits of the Greek men of science, who summed up in a series of systematic records the knowledge obtained by merchants, by soldiers, and by travellers of the extent of the world known to the ancients.  Of this knowledge, by far the largest amount was gained, not by systematic investigation for the purpose of geography, but by military expeditions for the purpose of conquest.  We must now retrace our steps, and give a rough review of the various stages of conquest.  We must now retrace our steps, and give a rough review of the various stages of conquest by which the different regions of the Old World became known to the Greeks and the Roman Empire, whose knowledge Ptolemy summarises.

[Authorities: Bunbury, History of Ancient Geography, 2 vols., 1879; Tozer, History of Ancient Geography, 1897.]

CHAPTER II

THE SPREAD OF CONQUEST IN THE ANCIENT WORLD