TERRESTRIAL MAGNETISM, ETC. 231 



of the dynasty, and first Emperor, till the beginning 

 of Yao's reign is very doubtful. Assuming the 

 date of Yao's death to be correct, we may safely 

 conclude that Hoang Ti must have lived some 

 time about 2400 or at the latest 2350 years before 

 the Christian era. Duhalde's work was founded on 

 narratives written by French Jesuit missionaries 

 who lived in China during the latter part of the 

 seventeenth century, and before publication was 

 most scrupulously revised and corrected, when 

 necessary, by the Pere Contancin, who had spent 

 thirty-two years in China. It is impossible to 

 doubt but that the narrative represents accurately 

 the traditions current in China at that time. 

 The instrument which the Emperor Hoang Ti is said 

 to have used cannot possibly have been anything but 

 a compass, as nothing else could have done what 

 it is said to have done. It is then perfectly cer- 

 tain that at the time when the quoted tradition 

 originated, the Compass was known in China. 

 We have thus irrefragable evidence that the com- 

 pass was known at a very early time in China, and 

 fairly strong evidence for believing it to have been 



