The Causes and Phenomena of Earthquakes. 79 



On 24th May, 1861, Wills and King heard a like explosion on 

 Cooper's Creek; and lastly, Mr. Landsborough, on 18th May, 

 1862, heard a similar report on the South Warrego, which he 

 thought was that of a gun, but it is very doubtful. 



The similarity of these noises to that of an aerial explosion, 

 like that of a cannon, might well attract notice at the time, and 

 when we find in the examples quoted that such explosions have 

 been heard at a distance from the locale of a shock, sometimes 

 preceding, sometimes following it, we may safely presume that 

 the noise was not of a falling tree (and in some of these six 

 instances recorded by our explorers, there was scarcely any 

 probability of such a solution), and therefore I include them in 

 my list of shocks. And let me remark, that they all occurred in 

 the same kind of country, and in the same geographical region. 

 I should be very glad to receive fresh data for the establishment 

 of these occurrences as indicating earthquakes ; and from Mr. 

 Kempson's letter (already named), it would appear that the flat 

 interior is subject to them. 



"With respect to the singular fact pointed out by Mr. "Wilton, 

 that the shock at Newcastle, in 1837, was felt strongly on the 

 beacon cliff, but not felt in the coal mines, twenty-three fathoms 

 below the surface, this is paralleled by some curious instances in 

 Australia. 



Daring the eighty shocks of earthquakes which were felt at 

 Maestricht, in Belgium, from February to April, 1756, the shocks 

 in general " were stronger in the upper parts of the houses than 

 on the pavement." During the same period, a great part of 

 England, France, and G-ermany was shaken ; and " in the coal 

 pits near Liege, the miners, at the depth of 900 feet, heard a 

 rumbling noise over their heads (and then felt the shock), whilst 

 those above ground heard a similar noise under their feet." 



Professor Perrey calls the attention of physicists to the cir- 

 cumstance, that in the silver mines of Marienberg, in Saxony, at 

 the beginning of this century, powerful shocks alarmed the 

 miners so that they ascended to the surface, where no shock was 

 felt at all. D Archiac, who quotes this case (Histoire des Progress, 

 Tom. I., p. 609), takes another from the Cosmos of Humboldt (I. 

 529) of an inverse kind, in the year 1823, when the miners of 

 Pahlun and Persberg felt no shock, whilst over their heads a 

 "violent earthquake greatly alarmed the inhabitants. 



This is precisely what Mr. "Wilton mentions, and which was 

 the case also at Newcastle on the 18th June last, where a number 

 of labourers who were working on the wharf " declare they felt 

 nothing of the shock whatever." It may be said they were so 

 occupied as not to distinguish the motion. 



In California, on the 29th May this year, miners underground 

 felt the shock that occurred at Virginia City very plainly, with 



