EXPLOSIVE OR BOOMING NOISES IN CENTRAL AUSTRALIA. 203 



intervals of several miles between them. In some places 

 there are groups of more than a dozen springs within sight 

 and in others only one or two. The upward flow of water 

 in the mud-springs would naturally be along fissures which 

 would continually enlarge and weaken the enclosing walls, 

 which might break with a crushing noise which would 

 reach the surface. The 4 desert sound ' is familiar to 

 residents of that district. 



When one of my sons, Mr. G. M. Mathews, was in Queens- 

 land some twelve or fifteen years ago, he told me that 

 subterranean noises are frequently heard in the vicinity of 

 Mount Gregory, between the Belyando River and Mistake 

 Greek, approximately in latitude 22° and longitude 146f°. 

 It is curious that this corresponds closely to the locality 

 where Sir Thomas Mitchell heard the sound described by 

 him in his ' Tropical Australia,' pages 280-81. Most of the 

 rumbling sounds referred to by me took place in the even- 

 ing, but I attribute that fact to the quietness prevailing 

 at that time. I am of opinion that they occur at any hour 

 of the day or night in the districts mentioned, and prob- 

 ably at other places from which no reports have yet been 

 published. 



After the reading of Dr. Oleland's paper, I wrote to my 

 son Mr. H. B. Mathews, Surveyor, Moree, knowing that 

 he had heard similar sounds, and have only just received his 

 reply, as he was away on field duty. He says, "When 

 camped on Doyle's Greek, County of Hunter, on 7th May, 

 1906, one evening about 7 o'clock, I heard a distant boom- 

 ing noise coming from the west. The evening was perfectly 

 clear and there was no wind to speak of. The country to 

 the westward of my camp was hilly for a long distance." 



