THE SOUTH-AFRICAN DIAMOND-MINES. 469 



cessfully conducted. A shaft is sunk in the blue to a total depth of 

 five hundred and twelve feet below the red soil, and two sets of work- 

 ings are opened up — one at this lowest level in course of preparation, 

 while a first level eighty feet higher is now being worked out. At 

 each level two sets of tunnels are used, one above the other, at a ver- 

 tical distance of fifty feet apart. The upper tunnels give the level at 

 which the excavation of large chambers is begun ; and these are grad- 

 ually worked downward, the roof being left untouched, while the ex- 

 cavated ground is delivered down vertical passes to the trucks in the 

 lower or main tunnel. 



The De Beer's mine is similar in formation to the Kimberley mine, 

 but about one fifth larger in area. The reef incasing it for a depth 

 of one hundred feet is a yellow basalt, after which succeeds a layer 

 of black shale, extending to a total depth of two hundred and ninety 

 feet from the red sand, where the hard igneous rock is struck. Within 

 the mine the diamondiferous soil is " yellow ground " to a depth of 

 one hundred feet from the surface, after which follows an unknown 

 depth of " blue ground." As in the Kimberley mine, the richness of 

 the ground greatly varies in the different sections. Having the ad- 

 vantage of the experience of the Kimberley, this mine has been steered 

 clear of serious difficulties from reef. But some falls of reef which 

 took place in 1883 and 1884, and a fall of nearly half a million loads 

 of top unpayable ground, foi*ced the claim-holders to consider some 

 alternative to continuous working in the oj:>en mine ; and it has become 

 apparent that the future excavations must proceed underground. Five 

 out of the seven companies holding the mine have sunk shafts within 

 it for the purpose of reaching the "blue ground." One company has 

 a shaft outside of the reef-margin, with a tunnel leading into the mine 

 at a depth of one hundred and fifty feet from the surface. Another 

 company has sunk a shaft from the outside at an angle of thirty-five 

 degrees from the vertical to a depth of five hundred feet from the sur- 

 face, from which working-galleries open at depths of five hundred and 

 three hundred and eighty feet. This mine, like the Kimberley, is 

 reduced in size at the cutting in of the hard rock. 



The Bultfontein mine is almost circular in shape, with a diameter 

 of about three hundred yards. It does not present equal prornise to 

 the operator with the two mines already described, and a considerable 

 proportion of its claims are still unworked, while others have been 

 abandoned on account of the encroachment of a mass of shale upon 

 them. No underground workings having been begun in it, it presents 

 to the casual observer a better idea of the nature of the operations 

 that have been carried on within the last ten years than any of the 

 other three mines, and for that reason it has been chosen to furnish a 

 model of diamond-mining for the Indian and Colonial Exhibition. 



The Dutoitspan mine derives its name from the " pan," or small 

 lake, which lies between it and the Bultfontein mine. This pan is filled 



