232 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



was practically 110 evidence of flame or heat. He, however, 

 admitted in cross-examination that carbon monoxide played a 

 part in the after effects of his supposed wind-blast, and that 

 carbon monoxide, under the circumstances, could only be pro- 

 duced by the incomplete combustion of coal dust; but he 

 thought the heat produced by the compression of the air 

 was sufficient to cause the coal dust to distil with- 

 out flame. Assuming that an area of roof 44 yards square 

 fell in a block in a little under half a 1 , second from a height 

 of six feet, and that 50 per cent, of the air beneath the falling 

 roof escaped into the surrounding goaf, or into the space from 

 which the fall came, he reckoned that the velocity of air out 

 of the 4th Right would be 700 miles per hour. The damage 

 done at a great distance from the 4th Right, such as the 

 overturning of skips at Price's Flat, 32 chains away by road, 

 which could not have been caused by the direct force of the 

 wind-blast, he accounted for by saying that the percussion pro- 

 duced by the fall would operate at long distances, though there 

 would be no direct forcible motion of the air. He did not 

 see any smoke himself ; but the smoke of which the witnesses 

 had spoken would be caused by the distillation of the dust. 

 He could not account for the heat observed by several wit- 

 nesses in the mine shortly after the disaster, except by the 

 disarrangement of the ventilation. 



These remarkable views appear to have had little or no 

 support by facts. As emanating from the consulting engineer, 

 they were given due consideration, but the Commission con- 

 sidered this wind-blast theory depended on too many assump- 

 tions, some of w T hich were quite untenable. It was assumed 

 that an area of roof 44 yards square fell in a body from a height 

 of 4ft. Gin. above the floor; that the time of falling was about 

 half a second (the rate at which it would fall in vacuo) ; and 

 that it would drive out half of the air beneath it through an 

 opening 12ft. by 6ft. Allowance does not appear to have been 

 made for the fact that the time of the fall would be prolonged 

 by the resistance of the air beneath, which would be enormous 

 if the air were to be, according to the hypothesis, compressed 

 to such an extent as to raise its pressure from, say, 1411). to 

 351b. per square inch, for a resistance of only 281b. per square 

 inch would balance a mass of rock of at least 24.6 feet in 

 height. The hypothesis, the Commission added, even if it 

 be possible, is certainly grossly improbable. Mr. Leitcli, who 

 was under-manager of Mt. Kembla up to six weeks before the 

 disaster, gives the area which remained to fall as only 1242 

 square yards, not 44 yards square as assumed by Dr. Robert- 

 son. This would be quite insufficient to develop the energy 

 requisite to support the wind-blast theory. Moreover, experi- 

 ence shows that the rock would not fall in a solid sheet, but 

 rather that it would crack and break up in numerous pieces. 



