292 Mr D, Milne on Earthquake'Shocks i?t Great Britain, 



pearance of clouds, with a notable defuscation. The 1st No- 

 vember, early in the morning, a thick fo^ arose."* 



It is stated by an eye-witness, that, at Lisbon, the earth- 

 quake of 31st March 1761 was followed next morning by 

 ''^reat/o//s:'f 



The Chichester earthquakes of November 1833 and January 

 1834 are stated to have been preceded by thick fogs ; and, 

 with regard to the former, it is specially mentioned, that the 

 thick fog preceding it was recognised as " precisely similar 

 to the fog which accompanied the Lisbon earthquakes in 1807 

 and 1816." 



Under date August 1786, it is mentioned, that, on the even- 

 ing preceding the shock, " a thick fog came on." 



11. The next phenomenon deserving of notice in this place, 

 is the appearance o£ a Jine powder, or dust, covering consider- 

 able districts of country^ which is thought to be connected with 

 earthquake-shocks. 



Two cases of this class are mentioned in the register, under 

 dates October 20. and 23. 1755, and February 1837. 



The first case is explained by an eruption of K6tlugia,*a 

 volcanic mountain in the south side of Iceland, which took 

 place on the 17th October 1755, and continued till the 7th 

 November 1 755. It is stated that a column of fire rose from 

 the crater which was seen at the distance of 180 miles, and 

 the atmosphere was so filled with smoke and ashes, that the 

 adjacent parishes were in a state of complete darkness.^ 



The other case has not received any explanation, and per- 

 haps it might not be thought worthy of any attention, were it 

 not that the phenomenon (if such it may be called) has seve- 

 ral times since been observed, with the additional circumstance, 

 that the dust or powder has been found covering considerable 

 districts of country. The subsequent cases now alluded to hav- 

 ing occurred after September 1839 (when the register ^tops), 

 they will not be farther noticed at present, falling more properly 

 to be afterwards described, with the continuation of the regis- 

 ter. Meanwhile, it may be observed that the powder which 

 was observed in Stratherne was (as stated in the Register) not 



* Discourses on Earthquakes, p. 315, t Philos. Trans, for 17G2, p. 423. 

 J Henderson's Iceland, i. 314. 



