26 THE DIAMOND MINES OF SOUTH AFRICA
the
unstable ground was systematically anticipated and restricted. No
feasible care in the direction of men working in such shifting ground
can entirely do away with casualties. Some are scarcely to be avoided,
but most are attributable, more or less, to the miners' heedless
disregard of the warnings of overseers and proper precautions.
There
was another serious risk in mining in the upper levels of the mines,
where shale is heavily impregnated with bituminous matter, and no
device could wholly prevent the gathering of carburetted hydrogen,
which, mingling with air, forms the " fire damp " that has been so
deadly a peril to miners. When sinking shafts or driving tunnels in the
shale, miners are prohibited by the strictest injunction of the
management, and the formal regulations of the Government Inspector of
Mines, from carrying any lighted candle into passages where there is
any possibility of this gas having gathered ; but no prohibition has
ever been able to prevent an occasional stretch of recklessÂness on the
part of some careless miner. Locked safety lamps are provided
abundantly for testing the atmosphere in such parts of the mine
workings, but neglect of this precaution has caused startling
explosions, scorching and striking men down, and in a few cases causing
death. In 1883 there was a slight explosion of accumulated gas in the
reef workings of the French Company, Kimberley mine. Here thin bands of
coal had been struck in the black shale, and in an upward drive to meet
a pass, some gas had collected in the interval from Saturday to Monday.
A naked flame set fire to this gas and caused the explosion. Prior to
this time two other cases were on record, in both of which workmen were
severely injured. Perhaps the most notable instance of the gathering of
this gas was in a heading of the workings of the Gem Company in De
Beers mine in July, 1885. One of the workmen had his face and hands
badly scorched by an explosion at the end of the heading, and a second
explosion occurred shortly afterward, when the managing director and an
overseer attempted to examÂine the heading, taking candles to light
their way. The director,
