326 FROM THE NIGER TO THE NILE 



occurs as a hard, finely foliated rock, and a fracture shows 

 a metallic lustre which when brought into contact with 

 moisture produces a blackish tint. All the poUshed ^ stone- 

 implements that have been found have a characteristic shape, 

 subject to hardly ^any variation. The districts where they 

 have occurred are bounded on the north by the Welle and 

 Dungu, on the west by the frontier of the Ubangui district, 

 while in the east they have been discovered in the Nile 

 Valley in the neighbourhood of Dufile and Wadelai, and also 

 in the basin of the upper Ituri. It is remarkable that no 

 other kinds of stone -implements have been found, such as 

 arrow-tips or knives, and that no tool has been discovered 

 with which these stones"^ might ^ have been made. The 

 districts to which I have alluded, where the stones have been 

 found, are inhabited by a great number of tribes, not one of 

 whom has kept any tradition of a time when the use of iron 

 was unknown to them, and they are ignorant of the origin 

 of the stones, believing them to be bolts of lightning which 

 strike trees and kill men. The Azandi call them " Mangua 

 Wgamba " or " axes of the lightning," and the Mangbettu 

 " Negbara Gombe " which means the same thing. They say 

 that these axes may often be discovered by turning up the 

 soil immediately a tree has been struck ; a httle later it 

 would be no good, because the stone would have gone back 

 to the clouds in order to strike again ! Many natives 

 attribute a mysterious power to them, believing that their 

 discovery announces a friend's approaching death, and the 

 Mangbettu cherish them as charms, every morning throwing 

 upon them the water with which they rinse their mouths in 

 order, as they say, to avert trouble. 



