66 Transactions of the South African Philosophical Society. 



towards the end of that year contained this statement : " Mud 

 Bushes : These have been much less frequent than during the 

 previous year, owing to the surface water having been taken up. 

 For many months no mud rushes of a serious nature have occurred." 

 Nevertheless it will show how little effect this high-level water 

 produces, that in the month of December, 1895, there was more mud 

 than ever before, or since, and in the following year (1896) there was 

 almost as much as in 1894 before the high-level water was interfered 

 with. 



It may be expected that the tunnel which is to be driven round 

 the rock, on the 1,000 foot level, between the blue ground and 

 quartzite, will give better results, and capture a lot of water that is 

 really dangerous. Yet it is doubtful at the best if anything but a 

 temporary security can be gained thus. Deeper levels are certain to 

 reintroduce the elements of mischief. Personally I am inclined to 

 think that variations of current meteorological conditions ought 

 not to be neglected at any time. I have recommended to the 

 directors of the De Beer's Company the free use of recording 

 aneroid barometers indicating on a very open scale, and these 

 instruments may shortly be provided. I have further ventured to 

 suggest that if traffic in the dangerous places could be stopped for 

 about a minute (so as to eliminate artificial eddies in the air) three 

 times a day, and observations taken of the behaviour of two candle- 

 flames, one near the roof and the other near the floor of the 

 tunnels, it might be possible to foretell a rush of mud. The Society 

 will judge of the chances of success. The idea is that, as a rule, 

 the heated air from the drilling and filling places should rise and 

 flow out under the roof of the tunnel, cold air flowing in along the 

 floor to take its place. The candle-flames ought therefore to be 

 deflected accordingly. But should a volume of mud be advancing 

 from its place within the bowels of the debris, the imprisoned air 

 lying between it and the miners being pushed rapidly on before, 

 might be expected to deflect both candle-flames outward. The wet 

 and dry bulb thermometers might also furnish some useful additional 

 data. Of course if any information could be gleaned in this 

 manner, a very rapid judgment would be essential as to the 

 proximity of the danger. 



