78 The Causes and Phenomena of Earthquakes. 



and at Roquemaure, in Languedoc, on 2nd September, 8imila r 

 explosions attended shocks. 



At Oban, in Argyleshire, " the watcher heard a noise like that 

 of a cannon discharged at a short distance," at a bottom of a 

 lighthouse where the vibrations were not felt, though the light- 

 house rocked. 



At Tiflis, in Georgia, two loud explosions accompanied a very- 

 severe vibratory shock, on 20th May, 1841. 



On 15th July, 1841, in Denmark, the air vibrated during 

 shocks, as during " a discharge of artillery ;" and a loud aerial 

 noise attended the tremor at Sparta, in Greece, on 12th June, 

 1842. Two explosions also accompanied a shock at Nantes, on 

 13th November, 1842. 



Lastly, to show the connection between such shocks and vol- 

 canic eruptions, I quote Mr. Campbell (Frost and Fire II. 374.), 

 who, in a letter dated 10th February, 1865, from Giarra, during 

 an eruption of Etna, thus writes : — " At the present moment, 

 while I am writing, all the windows of the house I am living in 

 have been broken by concussion, which was accompanied by an 

 earthquake. The noise is like a continued cannonading, with a 

 discharge from time to time of a hundred guns." Numerous 

 examples might be also quoted from eruptions of Vesuvius, and 

 in the Andes. 



These examples have been quoted from all available sources, 

 not only to confirm the reports of three of our earthquakes, but 

 to justify my belief that there have occurred (of which there is 

 no other evidence than such aerial noises) six other shocks, though 

 the observers have left no other phenomena on record. The bare 

 mention of the facts would only attract the passing attention of 

 the reader ; but viewed in connection with the preceding remarks, 

 I think I am justified in assuming that shocks of earthquake took 

 place at the times mentioned. 



One of these must have occurred between 27th August and 

 3rd September, 1845, and is thus referred to by Captain Sturt 

 (Central Australia. II. 25) : — 



" When Mr. Browne and I were on our recent journey to the 

 North, after having crossed the Stony Desert, being then between 

 it and Eyre's Creek, about 9 o'clock in the morning, we distinctly 

 heard a report as of a great gun discharged to the westward, at 

 the distance of half a mile. 



" On the following morning, nearly at the same hour, we again 

 heard the sound ; but it now came from a greater distance, and, 

 consequently, was not so clear. When I was on the Darling, in 

 latitude 30°, 1828, I was roused from my work by a similar 

 report ; but neither on that occasion nor on this, could I solve 

 the mystery in which it was involved." 



Sir Thomas L. Mitchell heard a similar report on the Darling. 



