EXPLOSIVE OR BOOMING NOISES IN CENTRAL AUSTRALIA. 193 



M. van der Broeck, after referring to the 'Barisal guns,' 

 says that he was disposed to regard the noises as due to 

 some peculiar kind of discharge of atmospheric electricity. 

 "But my colleague M. Rutot believes the origin to be 

 internal to the earth. He compares the noise to the shock 

 which the internal fluid mass might give to the earth's 

 crust." 



M. Clement Reed has informed M. van der Broeck that 

 he believes similar noises are heard on Dartmoor, and in 

 some parts of Scotland. I was not previously aware of 

 anything of the kind in these islands." Professor Darwin 

 then asks for further information from correspondents on 

 the subject. 



The article by La Touche, referred to by Sir George 

 Darwin, is entitled "On the Sound known as ' Barisal 

 Guns ' occurring in the Gangetic Delta." These are heard 

 in the delta and the hills to the north of it. He states 

 that five suggested explanations have been given of the 

 phenomenon, viz.: — (1) The breaking of surf rollers, (2) the 

 falling in of high banks, (3) the firing of bombs, (4) atmos- 

 pheric electricity, (5) subterranean or subaqueous volcanic 

 seismic agencies. None of these he considered entirely 

 satisfactory, except, perhaps, the last. He further suggests 

 that the noises may be due to slight movements of layers 

 of silt. 



As the result of Sir George Darwin's note, the next volume 

 (Vol. 53, 1895-6) of Nature contains contributions to the 

 subject from a number of writers. H. G. Olcott refers to 

 the Theosophist Magazine (Vol. 9, p. 705 and Vol. 11, p. 

 409) for his personal experiences of the Gangetic phe- 

 nomenon. This periodical I have not been able to consult. 

 He considers that the sound resembles an evening gun and 

 that all the theories so far proposed were inadequate. 



M— Sept. 6, 1911. 



