158 THE POPULAR SCIENCE MONTHLY 



before it was generally known." Another woman, in poor health, 

 ascribed the peculiar feeling that she experienced to an attack of heart 

 disease, and sank frightened in bed. Experiences of this kind have 

 been noted in other earthquakes and appear to be due to a morbidly 

 excitable condition of the ill-defined and unspecialized sense of general 

 well being. Some people perceived the earthquake chiefly through the 

 sense of touch, as when a man, seated in a chair and resting his legs 

 on a railing, " felt his legs shake," or as when a chief of police, also 

 seated, felt that his chair shook. In several other cases the earthquake 

 was likewise merely " felt." No doubt the sense of touch entered as 

 an important element in a far greater number of instances when men- 

 tion is made that something shook, trembled, quivered or rocked, or 

 when there was a jar or a tremor. The sense of equilibrium or of 

 poise was evidently involved in the case of a man who felt " dizzy," 

 and in the case of people who " wabbled on the streets," in cases where 

 occupants of houses noted a " heaving," " rocking " or a " swaying " 

 motion, and when people " were thrown down," or " nearly tumbled 

 over," or " found difficulty in keeping on their feet." 



The reports mention only five instances of sounds accompanying 

 the earthquake. Such sounds are general in the mesoseismal area in all 

 severe earthquakes in all parts of the world, except in Japan, and one 

 noted seismologist believes that their absence in that country is due to 

 a racial inability among the Japanese to hear sounds of very low 

 pitch. The general absence of sounds in the Illinois earthquake is 

 readily accounted for by its comparative weakness. It was faintly 

 audible only in three epicentral tracts. Some parties claim to have 

 heard a distinct rumbling before the shock in Dubuque. In Waukegan 

 one man described the quake as a rush of wind, and said that he had 

 heard it. This swishing noise is one of the many known characteristic 

 forms of earthquake sounds. In Springfield, 111., a faint rumbling 

 was heard, and a janitor in one of the school buildings in Peoria made 

 a similar observation. One man heard a sound like the " bumping of 

 a locked door." This is another variation of earthquake noises, which, 

 when more powerful, resemble volleys of musketry and artillery, and 

 which, like the other noises, originate under the ground. Many ob- 

 servations involve sounds which are, as it were, proxies of the quake, 

 induced by secondary events, such as the rattling of windows and 

 dishes, the crash of falling brick and the like. The student of earth- 

 quakes depends, as we have seen, on such noises for much of his in- 

 formation on the progress of the earth waves in the peripheral region 

 of the disturbed area. 



The sense that gives us the most reliable information on earth- 

 quakes, as on most other physical phenomena, is the sense of sight. 

 Visible earth waves are, however, rarely seen except in severe disturb- 

 ances. It is uncertain whether they appeared anywhere in this case. 



