218 LIGHT SCIENCE FOR LEISURE HOURS. 



great earthquake were experienced. Within historic 

 times Misti has poured forth no lava-streams, but that 

 the volcano is not extinct is clearly evidenced by the 

 fact that in 1542 an enormous mass of dust and ashes 

 was vomited forth from its crater. On August 13, 

 1868, Misti showed no signs of being disturbed. So 

 far as their volcanic neighbor was concerned, the 44,000 

 inhabitants of Arequipa had no reason to anticipate 

 the catastrophe which presently befell them. At live 

 minutes past five an earthquake-shock was experienced, 

 which, though severe, seems to have worked little mis- 

 chief. Half a minute later, however, a terrible noise 

 was heard beneath the earth ; a second shock more 

 violent than the first was felt ; and then began a sway- 

 ing motion, gradually increasing in intensity. In the 

 course of the first minute this motion had become so 

 violent that the inhabitants ran in terror out of their 

 houses into the streets and squares. In the next two 

 minutes the swaying movement had so increased that 

 the more lightly-built houses were cast to the ground, 

 and the flying people could scarcely keep their feet. 

 " And now," says Yon Tschudi, " there followed during' 

 two or three minutes a terrible scene. The swaying 

 motion which had hitherto prevailed changed into 

 fierce vertical upheaval. The subterranean roaring 

 increased in the most terrifying manner : then were 

 heard the heart-piercing shrieks of the wretched people, 

 the bursting of walls, the crashing fall of houses and 



