The Blue Ground. 41 



has ever dug into the earth, the area of the former 

 at the surface bemg thirteen acres, with a depth of 

 •450 feet, the area and depth of the Latter being- 

 even greater. These mines are no longer worked 

 from the surface, Ijut from shafts sunk at some 

 distance from the original holes, and penetrating to 

 the blue ground by transverse drivings at depths 

 varying from 500 to 1200 feet. The blue ground, 

 when extracted, is carried in small iron trucks 

 to the " floors." " These are made by removing 

 the bush and grass from a fairly level ^iece of 

 ground ; the land is then rolled and made as 

 hard and as smooth as j^ossible. These ' floors ' 

 are about 600 acres in extent. They are 

 covered to the depth of about a foot with 

 the blue ground, which for a time remains on 

 them without much manipulation. The heat of 

 the sun and moisture soon have a wonderful effect 

 upon it. Large pieces which were as hard as 

 ordinary sandstone when taken from the mine, 

 soon commence to crumljle. At this stage of the 

 work, the winning of the diamonds assumes 

 more the nature of farming than of mining ; the 

 ground is continually haii'owed to assist pulveriza- 

 tion by exposing the larger pieces to the action 

 of the sun and rain. The blue ground from 

 Kimberley mine l^ecomes quite well pulverized in 

 three months, while that from De Beers requires 

 double that time. The lono-er tlie oround remains 

 exposed, the l)etter it is for Avasliing." ^ The 

 process of exposure being completed, the blue 

 ' Keport, 1890, General Manager, De Beers. 



