126 MAPS AND THEIR MAKERS 



on their predecessors. When allowance is made for this, Blaeu*s 

 world map of 1648 may be regarded as marking the highest 

 achievement of Dutch cartography. Upon it are drawn the 

 coastlines of northern and western Australia, of southern 

 Tasmania, and of parts of New Zealand, representing the 

 achievements of Abel Tasman. The coasts of China are greatly 

 improved, no doubt from Dutch charts, and something like 

 the true form of the continental coast north of Japan begins 

 to emerge, as the result of the voyage of Maerten Gerritsz 

 Vries. In the Arctic Spitsbergen is partially represented, and 

 the work of the English in and around Baffin and Hudson 

 Bays is delineated, though the orientation of Baffin Bay is at 

 fault. 



To Blaeu's credit must also be set the abandonment of the 

 great hypothetical southern continent and of the four great 

 islands shown by Mercator as surrounding the North Pole. 

 Against these must be set blemishes such as the faulty orienta- 

 tion of the Amazon and the Rio de la Plata, and the retrograde 

 step of delineating California as an island. A common error in 

 this type of map was the undue longitudinal extent allotted to 

 the continents, especially to Asia. This was partly due to 

 the authority which Ptolemy still exerted, and also to the almost 

 total lack of reliable observations for longitude. On this map 

 of Blaeu's, the extreme longitudinal extent of Africa is re- 

 presented as approximately 80°, an exaggeration of some 12°; 

 Asia, eastwards of the Mediterranean, is allotted 90°, instead 

 of 85°, and South America 55°, instead of 46°. On the Hondius 

 map of 1608, these exaggerations are even greater (Africa by 

 nearly 16° and South America by as much as 27°); but Asia, 

 by some chance, is almost correctly represented. It is note- 

 worthy that the elder Blaeu, shortly before his death, was 

 aware that the conventional length assigned to the Medi- 

 terranean was greatly exaggerated. Despite these defects the 

 map gives a recognizable outline to the continents, and little 

 further progress could be expected without a fundamental 

 advance in method, particularly in the determination of 

 longitude. There is another noteworthy aspect of these maps, 

 their high technical and artistic quality, which may well have 

 been their chief merit in contemporary estimation. To excel 



