80 The Causes and Phenomena of Earthquakes. 



" a terrible rumbling as if tie roof of the works bad fallen in ; " 

 and, from tbe accounts I bave read, tbe sbaking above ground 

 was severer still. 



It can bardly be doubted tbat some of tbe above examples 

 belong to M. de Bylandt's tbird class of earthquakes, as in some 

 way connected witb electric and otber adventitious forces , a 

 conclusion I would also admit in relation to our sbock of tbe 18th 

 June, as experienced on tbe Hunter Eiver. 



Eespecting tbe sbock of 1809, felt at Prospect, Mr. Lawson 

 remarked to me, tbat it changed tbe well waters from fresh to 

 salt. This may merely refer to a local circumstance, tbe whole 

 of the soil in the formation on which his house stood being 

 naturally saline, and the effect of draining off the fresh water 

 might be to allow the saline springs to operate. 



If the subject deserves further consideration, the enquirer may 

 be referred to examples of mineral changes produced in springs 

 by earthquakes, as recorded in Perrey's catalogues, and in the 

 valuable Report of Dr. Daubeny " on Mineral and Thermal 

 waters," wherein he not only alludes to the influences of earth- 

 quakes, but to the effects produced on water by mineral proper- 

 ties of soils. 



He also alludes to the possibility, that salt may be formed (a s 

 in certain strata) by volcanic action. (Report B.A. 1836), and 

 during the earthquakes of 26th December, 1755, in the Alps of 

 Europe, some of the wells there became salt. 



I would now offer a few remarks on the shocks recorded by 

 myself at Parramatta in 1841, and at St. Leonards in 1868. 



Respecting the direction and time of the former I have no 

 doubt. At the moment of its occurrence I was in bed, being 

 unwell, and bad my face turned towards the clock on the church, 

 facing to and not far from the window, wishing to know the time. 

 The other observers, with one exception, mark the time as 8 

 o'clock. But Mr. Mackinlay, of William's Eiver, states that he 

 felt tbe shock there at a quarter-past 7. If his time was correct 

 there must have been two shocks that morning. Moreover, he 

 states that the motion lasted from ten to fifteen seconds, whereas 

 the motion was felt by myself during not more than five seconds. 



The direction was a little east of north, determined in a way 

 that could not deceive, by an observation on the soap-suds thrown 

 up in the hand-basin in the room, and which is the next best 

 indication to that of treacle. In that instance the shock came 

 from the direction of Maitland, and Mr. Dunlop, the late Astron- 

 omer, who at first ridiculed the idea of my turning a basin into 

 a seisometer, afterwards, when he had returned from a visit to 

 the Sugarloaf, near Maitland, apologised for what he had said, 

 and acknowledged himself satisfied that I was right. Some 



