352 Prof. Biscbof 07i the Natural History of 



it is going rather too far to take the explosion of fire-damp for 

 the cause of earthquakes, as Kries does.* It is not impossible, 

 that what has been taken for flames, if not altogether an illu- 

 sion, was only an appearance of light, produced by the sudden 

 expansion of highly compressed gases, exactly the same as is 

 seen when an air-gun is discharged in the dark. 



The heating and boiling up of the water in the sea and in 

 lakes, the spouting up of streams of water, as well as the ejec- 

 tion of various substances from fissures in the earth,*]- which 

 have occasionally been witnessed, may be satisfactorily ex- 



* In his prize-essay on the causes of earthquakes. 



t Yon HofFL c. t. xxv. p. 73, t. xxix. p. 421. At the time of the earth- 

 quakes, which destroyed a part of Italy (1702-1703), many rents were 

 formed in the Abruzzij which emitted a large quantity of stones and then 

 troubled water. The latter was thrown up higher than the trees in the 

 neighbourhood. Flames and a thick smoke rose from the neighbouring 

 hills, which continued three days with some interruptions. Hist, de I'Acad. 

 an. 1704, p. 10. During the earthquake, the 21st October 1766, which totally 

 destroyed the city of Cumana, the earth opened at several places in the pro- 

 vince, and vomited sulphureous water. These eruptions were particularly nu- 

 merous in a plain, which extends towards Casana^/ two geographical miles east- 

 ward of Cariaco, and which is known by the name of the holloic land Ctierra 

 Tiueca) because it seems to be every where undermined by hot springs. 

 Von Humboldt Keise, t. i. p. 482. During the violent earthquake, which 

 in one minute overthrew the city of Caraccas, on the 26th March 1813, so 

 much water was thrown up through the cracks, that a new stream was form- 

 ed. At the same time the ground was also found covered with a fine white 

 earth, like volcanic ashes, which had been thrown up from fissures in the 

 neighbourhood. The eruptions of volcanic masses were still more consi- 

 derable during the earthquake of Biohamha, 1797. The earth was fissured 

 at innumerable places, and immense gulfs were formed in some places. 

 Masses of water rose, filling up valleys 1000 ft. wide, and 600 ft. in depth ; 

 and also at the same time a peculiarly stinking mud, consisting of vol- 

 canic matter, accumulated so as to form considerable hills, now called moya. 

 Wide rents were likewise opened during the violent earthquake in the 

 north coasts of South America^ last year, in order to give exit to streams of 

 water which rose. It was often observed, that during the earthquakes, 

 water with sand, mud, &c., was thrown up from wells, sometimes to a height 

 of 30 ft. Von Humboldt relates, (Relat. Hist,, t. ii. p. 287) that this pheno- 

 menon is generally observed during the earthquakes at Cumana. The same 

 thing happened the 1st Nov. 1755 near Colares (Philos. Trans, t. xlix. 

 p. 416.), and also during the earthquake in Calabria. (Journ. de Phys. lxii» 

 J). 263.) 



