http://b4hntuy3fimfh2227vf4f74emnya7p35i5brtqujs6leqvtclfwvjbqd.onion/doc/physics/diamonds-crookes/The%20Project%20Gutenberg%20eBook%20of%20Diamonds,%20by%20William%20Crookes..html
By this ingenious method every
portion of blue ground is excavated and
raised to the surface, the rubbish on the
top gradually sinking and taking its place. [45] The scene below ground in the labyrinth
of galleries is bewildering in its complexity,
and very unlike the popular notion of a
diamond mine ( Fig. 7 ). All below is dirt, mud,
grime; half-naked men, dark as mahogany,
lithe as athletes, dripping with perspiration,
are seen in every direction, hammering,
picking, shovelling,...