EARTHQ UAKE-PHENOMENA. 



5 2 3 



The diagram shows the waves radiating from the earthquake focus 

 A to c d ef and g successively, and reaching the surface at B, where 

 the shocks would be vertical. At 1 2 3 they become more and more 

 oblique, and at greater distances appear almost horizontal. 



Fig. 9. 



Continuous Waves fbom a Single Shock. 



Now, while the movement of the transit-wave may be very rapid, 

 that of the particles of matter is surprisingly small. At Lisbon the 

 velocity of the wave was 20 miles a minute, or 1,200 miles an hour. 

 According to Mallet, where the velocity of the transit wave was 1,000 



DlAGBAM SHOWING THE MOVEMENT OP WAVES FBOM THE CeNTBE OB FOCUS. 



B, point where the shocks would be vertical. ] 2 3 and 1' V y are points where the waves would reach 



the surface. 



feet per second, the movement of the particles was only 12 feet per 

 second, or eight miles an hour, and he states that three columns of the 

 Temple of Serapis, on the shore of the Bay of Baise {see frontispiece), 

 a region subject to earthquake-shocks, would be overthrown by a shock 

 " whose wave-particles had an horizontal velocity of 3$ feet per second." 

 The shock which threw human being-s 100 feet in the air, at Riobamba, 



O 7 7 



must have had a velocity of 80 feet per second. The theory of Mr. 



