172 DIAMONDS AND 



indeed the ancient bed of the river. To get at this, the stream is 

 dammed off in the dry season, and shafts, from 6 to 30 ft., sunk 

 to this diamond-bearing layer, and the gravel is brought to the 

 surface in baskets by negroes, and stored by the washing-sheds to 

 be examined during the rainy season. The season during which 

 the ground can be excavated is very short ; I believe, not above 

 ten weeks, at the end of which time the rains commence suddenly 

 in such deluges as to destroy all works, carrying away the em- 

 bankments and filling up all the holes, and the following season 

 the miners have to begin again anew, and as all trace of former 

 workings are obliterated, it not unfrequently occurs that a miner 

 sinks his shafts on ground already worked, and thus has the 

 season's work wasted. In this way, and owing to the great diffi- 

 culties to be overcome, diamond-mining in the Sierras has become 

 a most precarious and dangerous operation. In the third district, 

 that of Bahia, the Diamonds are also found in an alluvial gravel, 

 but instead of occurring in the ancient beds of rivers, this gravel 

 is spread in a very thin Stratum over the face of the country, close to, 

 or on the surface, and requires little more than to be raked up and 

 washed. In a locality discovered about a year since, called Cana- 

 viras, near Bahia, and now being worked with success, the gravel 

 lies quite on the surface, and forms a stratum not six inches thick, 

 and although the area over which it extends is very considerable, 

 it is estimated it will be worked out in two years. In 1841, a 

 paper was read before the Academy at Brussels by M. P. Chasseau, 

 in which he claimed that in one locality the Sierro di San Antonio 

 di Grammagoa, the Diamond had been found in its matrix rock. 

 He described it as " gres psammite," and it is, I believe, the same 

 as the Itacolimite of other authors, which has been frequently 

 described as a kind of sandy freestone. It is, however, a mistake 

 to suppose that this is the rock in which the Diamond is formed. 

 It is only a somewhat compact conglomerate, formed of the same 

 elements as the cascalhao. 



I will now turn to the South-African Diamond-fields, the rich- 

 est and most interesting in the world. The existence of Diamonds 

 at South Africa had been asserted many years ago, and there is a 

 mission-map, dated as far back as 1750, on which is written, across 

 the district of West Griqualand, " Here be Diamonds," and it is 



