TE11EESTRIAL MAGNETISM. 51 



which has exerted so powerful an influence on the improve- 

 ment and extension of navigation, and, in consequence of 

 the practical and material services which it has thus rendered, 

 has given so persistent an impulse to the study of an all- 

 pervading, yet formerly little regarded, natural force. In 

 the history of the principal epochs in the Physical Contem- 

 plation of the Universe, ( 53 ) the subject of the earth's 

 magnetism, which we now bring under one general view, 

 assigning the several sources or authorities from whence the 

 information is derived, fell under several different chrono- 

 logical heads, and was there divided among different 

 sections. 



It is among the Chinese that we find the first application 

 of the magnetic directive force to practical purposes by the 

 employment of magnetised needles floating on water, which 

 goes back to an epoch anterior perhaps to that of the 

 Doric migration and the return of the Heraclides to the 

 Peloponnesus. It is remarkable that in this part of Asia 

 the use of needles, the south end of which was the one dis- 

 tinguished, as with us the north, commenced in land journeys 

 before their employment in sea navigation. Instead of a 

 ship's compass they used a magnetic car, on the front part 

 of which a floating needle carried a little figure, whose out- 

 stretched arm and hand pointed to the south. Such an 

 apparatus, Pse-nan (indicator of the south), was presented, 

 under the dynasty of the Tscheu, 1100 years before our era, 

 to the ambassadors from Tunkin and Cochin-china, to 

 guide them across the great plains on their return from 

 China to their own country. The magnetic car continued 

 to be used as late as the 15th century. ( 54 ) Many such 

 instruments were kept in the Emperor's palace, and it 



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