322 



tomed to hear the thunder roll beneath their 

 feet % as it is heard by us in the region of the 

 clouds. Confidence easily springs up in the 

 human breast, and we end by accustoming 

 ourselves on the coast of Peru to the undula- 

 tions of the ground, like the sailor to the toss- 

 ings of the ship, caused by the motion of the 

 waves. 



The earthquake of the 4th of November ap- 

 peared to me, to have had a sensible influence 

 on the magnetical phenomena. In a short 

 time after my arrival on the coasts of Cumana, 

 I had found the dip of the needle 43 53° of the 

 centesimal division. Some days before the 

 earthquakes, I was occupied very assiduously 

 in verifying this result. The governor of Cu- 

 mana, who was in possession of several scienti- 

 fic books, had lent me the interesting Tratado 

 de Navegacion of Mendoza. I was struck with 

 the assertion there made *f~, " that the monthly 

 and horary fluctuation of the dip of the needle 

 is greater than that of the magnetic variation." 

 A series of observations, which I had made in 

 1798, conjointly with the Chevalier Borda at 

 Paris, and afterwards by myself at Marseilles 

 and Madrid, convinced me, that the diurnal 

 variations could not be perceived in the best 



f Los bramidos de Guanazuato* See vol. ii, ch. iv, p. 228. 

 f Vol. ii, p. 72. 



/ 



