52 TERRESTRIAL MAGNETISM". 



was also customary to use them in determining the direction 

 of the walls when building Budhistic convents. Their 

 frequent employment led some of the more acute thinkers to 

 form physical speculations respecting the nature of the 

 magnetic phenomena. The Chinese panegyrist of the 

 magnetic needle, Kuopho, a contemporary of Constantine 

 the Great, compared the attractive force of the magnet 

 to that of rubbed amber. " It is/' he says, " as if a 

 mysterious breath passed through both, communicating 

 itself with the swiftness of an arrow." The symbolical 

 expression of "a breath" reminds us of the equally 

 symbolical expressions used in Grecian antiquity by 

 the founder of the Ionic school, Thales, in reference 

 both to the magnetic stone and > to amber, which were 

 said to be " animated," or imbued with a " soul" or " spirit," 

 meaning evidently an indwelling principle of motive 

 activity. ( 55 ) 



As the too great mobility of these Chinese floating 

 needles was found inconvenient, they were replaced in 

 the beginning of the 12th century by a different con- 

 struction, in which the needle was suspended freely in 

 the air by a cotton or silken thread, quite in the manner 

 of the " Coulomb" suspension, which was first employed in 

 Europe by Gilbert. With this improved apparatus, ( 56 ) 

 the Chinese even determined early in the 12th century 

 the amount of the west declination, which appears to 

 undergo only very slow and minute changes in that part 

 of Asia. At length the compass came to be employed at 

 sea as well as on land. Under the dynasty of Tsin, in the 

 4th century, Chinese ships guided by compasses visited the 

 ports of India and the eastern coast of Africa. 



