134 ORIGIN OF THE AMERICAN NEGRO. 
with each other by two tunnels running north and south, one near 
the west side of the mine and one midway between it and the east 
margin of the mine. 
Fromi the east and west tunnels offsets are driven to the sur¬ 
rounding rock. When near the rock, they are widened into gal¬ 
leries, 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 over¬ 
head; as the roof is 
blasted back the debris 
follows. When stoping 
between two tunnels, the 
blue is stoped up to the 
debris about midway be¬ 
tween the two tunnels. 
The upper levels are 
worked back in advance 
of the lower levels, and 
the works assume the 
shape of irregular ter¬ 
races. 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 down and taking its place. 
The scene below ground in the labyrinth of galleries is be¬ 
wildering in its complexity, and is about as little like one’s idea of 
a diamond mine as can well be conceived. Electric light is uni- 
