1897.] on Diamonds. 481 



but is pretty constant in the same mine. In 1890, the yield per load 

 of blue ground was — 



. From the Kimberley mine from 1' 25 to 1*5 carat. 

 „ De Beers mine „ 1-20 ,,1-33 „ 



„ Dutoitspan mine „ 0-17 „ 0*5 „ 

 „ Bulfonteiu mine „ 0*5 „ 0'33 „ 



In the face of constant developments I can only describe the 

 system in use at the time of my visit. Shafts are suuk in the solid 

 rock at a sufficient distance from the pipe to be safe against reef 

 movements in the open mine (Fig. 7). Tunnels are driven from this 

 shaft at different levels, about 120 feet aj)art, to cross the mine from 

 west to east. These tunnels are connected by two others running 

 north and south, one near the west side of the mine and one midway 

 between it and the east margin of the mine. From the east and west 

 tunnels offsets are driven to the surrounding rock. When near the 

 rock, the offsets widen into galleries, these in turn being stoped on 

 the sides until they meet, and upwards until they break through the 

 blue ground. The fallen reef with which the upper part of the mine 

 is filled sinks and partially fills the open space. The workmen then 

 stand on the fallen reef and drill the blue ground overhead, and as 

 the roof is blasted back the debris follows. When stoping between 

 two tunnels the blue is stoped up to the debris about midway between 

 the two tunnels. The upper levels are worked back in advance of 

 the lower levels, and tlie works assume the shape of irregular terraces. 

 The main levels are from 90 to 120 feet apart, with intermediate 

 levels every 30 feet. Hoisting is done from only one level at a time 

 through the same shaft. By this ingenious method of mining every 

 portion of blue ground is excavated and raised to the surface, the 

 rubbish on the top gradually sinking and taking its place. 



The pcene below ground in the labyrinth of galleries is bewil- 

 dering in its complexity, and very unlike the popular notion of a 

 diamond mine (Figs. 8, 9). All below is dirt, mud, grime ; half naked 

 men, black as ebony, muscular as athletes, dripping with perspiration, 

 are seen in every direction, hammering, picking, shovelling, wheeling 

 the trucks to and fro, keeping up a weird chant which rises in force 

 and rhythm when a titanic task calls for excessive muscular strain. 

 The whole scene is more suggestive of a coal mine than a diamond 

 mine, and all this mighty organisation, this strenuous expenditure of 

 energy, this costly machinery, this ceaseless toil of skilled and black 

 labour, goes on day and night, just to win a few stones wherewith to 

 deck my lady's finger ! 



Owing to the refractory character of blue ground fresh from the 

 mines, it has to be exposed to atmospheric influences before it will 

 pulverise under the action of water and mechauical treatment. It is 

 brought to the surface and spread on the floors (Fig. 10). Soon the 

 heat of the sun and moisture produce a wonderful effect. Boulders, 

 hard as ordinary sandstone when fresh from the mine, commence to 



