INAUDIBILITY OF CERTAIN SOUNDS. 



owing, perhaps, to the violence of the pain, added to that 

 kind of apprehension which our situation unavoidably 

 inspired. This appeared to me the more remarkable, as 

 my case was totally the reverse. I was in a state of ex- 

 citement resembling the effect of some spirituous liquor. 

 J suffered no pain ; I experienced only a strong pressure 

 round my head, as if an iron circle had been bound about 

 it. I spoke with the workmen and had some difficulty in 

 hearing them. This difficulty of hearing rose to such a 

 height, that during three or four minutes I could not hear 

 them speak. I could not, indeed, hear myself speak, 

 though I spoke as loudly as possible ; nor did even the 

 great noise caused by the violence of the current against 

 the sides of the bell reach my ears." 



The effect thus described by Dr. Colladon is different, 

 from that anticipated by Dr. Wollaston. He was not 

 merely deaf to low tones but to all sounds whatever ; and 

 I have found by repeated experiment, that my own ears 

 become perfectly insensible even to the shrill tones of the 

 female voice, and of the voice of a child, when the drum 

 of the ear is thrown into a state of tension by yawning. 



With regard to sounds of high pitch at the other 

 extremity of the scale, Dr. Wollaston has met with 

 persons, whose hearing was in other respects perfect, who 

 never heard the chirping of the Gryllus campestris, which 

 commonly occurs in hedges during a summer's evening, 

 or that of the house-cricket, or the squeak of the bat, or 

 the chirping of the common house-sparrow. The note of 

 the bat is a full octave higher than that of the sparrow ; 

 and Dr. Wollaston believes that the note of some insects 

 may reach one octave more, as there are sounds decidedly 

 higher than that of a small pipe, one-fourth of an inch in 

 length, which he conceives cannot be far from six octaves 

 above the middle E of the pianoforte. " The suddenness 

 of the transition," says Dr. Wollaston, " from perfect 



