ON ITS EXTERIOR. EARTHQUAKES. 193 



being overthrown, straight and parallel rows of trees were 

 inflected, and in fields having two sorts of cultivation, one 

 crop even took the place before occupied by the other : the 

 latter phenomenon shewing either a movement of translation, 

 or a mutual penetration of different portions of the ground. 

 When making a plan of the ruined city of Riobamba, I was 

 shewn a place where the whole furniture of one house had been 

 found under the remains of another ; the earth had evidently 

 moved like a fluid in streams or currents, of which we 

 must assume that the direction was first downward, then 

 horizontal, and lastly again upward. Disputes concerning 

 the ownership of objects which had been thus carried to 

 distances of many hundred yards, were decided by the 

 Audiencia, or Court of Justice. 



In countries where earthquakes are comparatively rare, 

 for example in the south of Europe, an imperfect induction 

 has led to the very general belief that they are always pre- 

 ceded by calms, oppressive heat, and a misty horizon. ( 184 ) 

 This popular error is however refuted, not merely by mr 

 own experience, but also by the observations of all those 

 who have lived many years in districts such as Cumana, Quito, 

 Peru, and Chili, where the earth is frequently and violently 

 shaken. I have felt shocks in serene weather as well as in 

 rain, and during a fresh east wind as well as during a 

 storm. Even the regularity of the horary variations of the 

 magnetic declination, and of the pressure of the atmo- 

 sphere, ( 185 ) were not disturbed on the days of earthquakes. 

 My observations were made within the tropics ; and those 

 made by Adolph Erman in the temperate zone, during 

 an earthquake at Irkutsk near Lake Baikal on the Stb of 

 March, 1829, give a similar result. At Cum an a, on the 





