BY JAMES ANDREW. 103 



Kopje implies the locality was originally a hill, and from its site 

 20,000,000 of tons of diamondiferous ground and the surrounding 

 rock have been removed. Work of almost similar magnitude has 

 been simultaneously carried on at the three other mines, each but 

 little inferior in depth to Kimberiey, and two of considerably greater 

 area. 



The "blue ground," composed of pebbles and stones of various 

 kinds cemented together by a silicate of alumina or lime, is of 

 varying degrees of hardness in the several mines, and frequently 

 varies very much in quality in different sections of the same mine. 

 It has first to be loosened by blasting, and then, after being broken 

 with large hammers and heavy picks into pieces which can be 

 handled, it is hauled to the surface for future treatment. 



The hauling gear is of most ingenious construction. A complete 

 plant, consisting of a double serial tramway, each division or line 

 being constructed of two stout wire cables on which travels a frame 

 or four-wheeled carriage, bearing a large iron tub, slung on 

 trunnions, of a capacity of about 30 cubic feet. As the sides of 

 the mine are inclined at varying angles, and the tramway may for 

 some distance be either nearly perpendicular or nearly horizontal, 

 the slinging system is a necessity. 



From the large hopper receptacles, into which the "blue" is 

 received on the surface, trucks are filled and run on lines of railway 

 or trams to the outskirts of the camp. There being spread over the 

 surface of the ground, exposed to the disintegrating action of light 

 and weather, the "blue" remains until fit for treatment in the 

 washing machinery, the time varying from some two or three weeks, 

 under favourable circumstances, to so long as three months. 



The depositing floors are of great extent, a single company often 

 having 5,000 or 6,000 loads under treatment, and land for this pur- 

 pose was diflicult to obtain within a reasonable distance of the mine. 



Large lumps of " blue '' are frequently broken up with hammers. 

 I believe steam stone crushers have even been used for the purpose, 

 and rollers, clod crushers, and harrows, etc. , intended for agricultural 

 pursuits, have been brought into requisition for pulverising the 

 ground. The boundaries of the floors are marked by beacons and 

 by walls built up with refractory lumps of " blue " used with the 

 dual object of vacating valuable floor room and facilitating the 

 desired result by increased exposure. Careful watch has to be 

 kept over the natives employed in spreading and loading the ground 

 on these floors, as many of the finest diamonds are frequently 

 found there, as well as in the primary operations of blasting and 

 picking in the mines. Lumps always separate more readily at 

 the spot where a large stone is embedded than elsewhere. One 

 white man is usually placed in charge of from every five to ten 

 natives, with the sole duty of keeping watch against theft. The fine 

 gravel which results from this disintegration of the " blue " is next 

 treated in circular rotary washing machines, to which it is fed 

 through revolving cylindrical screens of graduated mesh, so as to 

 remove any remaining lumps. Several arms fitted with knives or 

 scrapers rotate in the washing machine, and stir up the diamond- 

 iferous ground mixed with water, which enters through an opening 

 in the outer edge of the machine. The lighter stuff comes to the 

 surface, and floats away through an aperture in the inner rim, and 

 the heavier gravel falls to the bottom of the pan. The inner cir- 



