Inquiry into the Origin of Mud Hushes in De Beers Mine. 55 



mining operations. The great rushes, on the other hand, are more 

 often of thicker mud mixed up with large and small lumps of " blue 

 ground " and " reef." On more than one occasion 1,000 linear feet 

 of tunnel have been packed full in a very few moments with mud of 

 this description, and it is this which so frightfully mangles the 

 unfortunate body overtaken by its onset. The blue prints annexed 

 show fairly well the area attacked by a typical mud rush ; though 

 not by any means the largest, they represent the last three of any 

 noteworthy magnitude. Figs. 1 and 2 depict the circumstances of 

 the double rush of September 9, 1896, on the 920 and 960 foot 

 levels, causing the deaths of three natives ; Fig. 3 depicts the rush 

 of October 17, 1896, on the 1,000 foot level, in which six natives 

 lost their lives ; Fig. 4 represents the rush of November 12, 1896, 

 on the 960 foot level, which was not attended with any fatality.* 

 On Fig. 4 will be seen a cross tunnel which the mud failed to pene- 

 trate, though each end was blocked. On all these pictures the close 

 lines drawn diagonally across the direction of the tunnels indicate 

 the portion of the mine from which the diamondiferous rock was 

 being excavated on that particular level when the rush of mud took 

 place. The red line on Fig. 1 marks the junction of the blue ground 

 and boundary rock. It occupies the same approximate position on 

 all the levels. 



The origin of the water in the mud is not very clearly understood. 

 The belief has been, general that it is directly due to the rainfall, 

 and further, that a heavy rainfall is always followed after an in- 

 terval of eight days by a mud rush. So much has this idea prevailed 

 that any further attempt to get to the root of the matter has been 

 deemed superfluous. It has even been said that a rainfall record is 

 as good as a dated list of mud rushes. Now since none of the deep 

 levels in the mine are free from the danger, and lives are certain to 

 be lost so long as a firm grasp is not obtained of the physical 

 agencies involved, it became very necessary to place this fact, if 

 fact it should prove to be, on a sure footing. Accordingly a list of 

 the dates on which mud rushes had taken place was compared with 

 the rainfall of Kenilworth, the rain-gauge being about two miles in a 

 direct line N.B. of the mine. It soon became apparent that, far from 

 the mud rushes following hard upon the rain, a season of drought 

 was, on the contrary, if anything, distinctly the more dangerous. 



Table 1 gives the monthly rainfall for the three years ; Table 2 

 the number of mud rushes in each month. 



* According to the official returns the total number of deaths caused by mud 

 rushes in the De Beer's Mine in the three years 1894-1896 is forty-five. 



