40 Dr. C. Davison on Earthquake- Sounds. 



duced by a heavy traction-engine passing, while another will 

 be equally positive that the shock was unaccompanied by 

 sound. Not only people in the same town, but persons in 

 the same house, and even in the same room, differ in this 

 respect. There is no reason, it should be remarked,, for 

 supposing that they were not equally alert, or that their 

 conditions varied essentially except in their powers of per- 

 ceiving deep sound. 



This point is so important that I venture to give further 

 evidence in illustration. 



M. Ch. Deville, who studied the Guadeloupe earthquake 

 of Feb. 8, 1843, remarks that " ce bruit . . . n'est pas percu 

 par tout le monde. Ni moi, ni les personnes qui m'entour- 

 aient, ne Favons entendu a la Dominique ; bien plus, peut- 

 etre par suite de Pemotion, une foule de temoins du desastre 

 de la Pointe-a-Pitre disent ne l'avoir point entendu. Quel- 

 ques uns afferment, au contraire, que ce bruit s'est prolonge 

 un petit nombre de secondes encore apres la commotion ; 

 pour d'autres, il a ete sensible dans quelques unes des 

 secousses de moindre violence qui se sont succede depuis 

 celle du 8. On pretend meme que chacune de ces dernieres 

 est annoncee par un bruit souterrain dans les ilets de la 

 rade de la Pointe-a-Pitre " *. 



" In the Tokio seismic area," says Prof. Milne, "sounds 

 accompanying earthquakes are rare. Although the author 

 has observed many earthquakes when sounds are said to have 

 been heard, it has only been once during a period of several 

 years that he can say that he distinctly heard a sound. This 

 was on March 11th, 1881, when a sound between hissing and 

 rumbling was heard "t. 



During the Hereford earthquake of 1896, if we take the 

 evidence only of those observers who were awake before it 

 began, we find that two out of five observers at Clifton did 

 not hear the sound, at Leamington two out of six, in Birm- 

 ingham and the neighbourhood four out of 23, in London 

 eight out of 18, and at Bangor two out of seven. In the 

 whole disturbed area, 148 persons who were awake heard no 

 sound, and all but five of these were within the boundary of 

 the sound -area. 



Partial Inaudibility to some Observers. — Similar evidence 

 is afforded by the partial inaudibility of the sound, by its 

 total cessation, generally during the shock itself, to some 

 observers, while others continue to hear it. In Great Britain 



* Observations sur le tremblenient de terre eprouve a la Guadeloupe 

 le 8 fevrier 1843 (Basse-Terre, 1843), p. 4. 



f Japan Seismol. Soc. Trans, vol. xii. 1888, p. 56. 



