PEOPERTIES OF SOUND. 363 



by. The little bones which form a chain from this membrane to the oval 

 one at the back of the drum participate in this movement, and, indeed, 

 serve to convey it, without much loss, across the cavity. It is consider- 

 ed that this is their function, since it may be proved experimentally that 

 wave sounds going through such a solid combination, surrounded by at- 

 mospheric air, pass with but very little loss of intensity. Under the im- 

 pulses thus communicated to it, the oval membrane commences to vi- 

 brate, and in those movements the water in the labyrinth joins ; and so 

 the filaments of the auditory nerve become aifected, and the sensation of 

 sound is transmitted to the brain. It is supposed that the three semi- 

 circular canals, which are set at right angles to one another, as it were, 

 occupying the three adjoining faces of a cube, are for the purpose of de- 

 termining in what direction the sound is coming whether upward, down- 

 ward, or laterally. Moreover, it is believed that the little muscles winch 

 operate on the membrane of the drum have the duty of tightening or 

 slackening it so as to receive the sounding waves in the most available 

 way. 



It is not necessary to enter on a lengthy criticism of this explanation. 

 Physiologists have long regretted that it assigns no use for Criticisms on 

 many of the most complicated and delicate arrangements con- this hypothe- 

 nected with the ear, offers no explanation of the manner in S1S ' 

 which that intricate organ is enabled to present to the mind the various 

 relations of sound, and is inconsistent with many of the facts of compar- 

 ative anatomy. Indeed, it is very plain that a true interpretation of the 

 action of the different regions and structures of the ear can only be given 

 from a conjoint study of the physical nature and properties of sounds, of 

 the peculiarities of the soniferous waves which it is necessary p r0 permodeof 

 for us to perceive, of the comparative anatomy of the ear as obtaining a 



i 11 , -1 ri't* i ^ , t true interpret- 



presented in all tribes ol liie ; and, since mere must be a cor- a tion of these 

 respondence among the lower tribes perhaps we might have functions - 

 said the higher too between the organs of voice and the organs of audi- 

 tion, the obscure points in the structure of the latter may be illustrated 

 by what is known of the former. To these might be added the study of 

 its embryonic development. It is by the aid of these different means 

 that I pass to the description of the function of audition. 



What, then, are the physical peculiarities existing in the waves of 

 sound which we actually perceive? They are these three, Three hvsical 

 1st. The intensity, that is, loudness or feebleness of the peculiarities of 

 sound; 2d. Its note or pitch; 3d. Its quality; for two sounds s< 

 of the same intensity and note may differ characteristically. The sound 

 of the violin differs from that of the flute, and this, again, from that of 

 the human voice. Our organ of audition is so constructed that it is af- 

 fected by each of these peculiarities, and transmits them to the mind. 



