Scientific Lectures. 197 



into the strangely shaped cavity small, rather heavy, solid bodies, 

 ■which will not vibrate readily or easily. In certain parts of the laby- 

 rinth we find particles of calcareous sand, imbedded among the deli- 

 cate nerve filaments, whose office it is to resist their motion, when they 

 tend to vibrate along with the water which fills the cavity, and acting 

 as drags to stretch, and thus stimulate them into activity. 



I hold in my hand a long india rubber string, stretched by a weight ; 

 if I raise the string slowly the weight readily follows, and the string 

 is not elongated more than before ; but when I attempt suddenly to 

 raise the string the weight resists, the string is greatly lengthened, 

 and it is possible, by a quick jerk, to cause it, as you see, to separate 

 from the weight. This last form of hearing apparatus is the simplest, 

 the least elaborate of the three, and we find it among the lower ani- 

 mals, where the more complex contrivances are, to a greater or less 

 extent, absent. As an example of the third class of sounds, I may 

 mention the snap of the electric spark, which is due to the production 

 of a single wave, as Toepler has demonstrated. 



Thus it would seem that the Creator has provided man with a most 

 elaborate and complicated piece of apparatus, with which it is practi- 

 cable to perceive and distinguish several thousand simple tones, and 

 the number of their possible combinations is, of course, infinite. 

 Think of the delicate care required to keep such an instrument in 

 order, its strings properly weighted and stretched, its rods all in tune, 

 day after day, during the process of growth and waste, to which it, 

 like the rest of the body, is constantly subjected. It gives us no care ; 

 we never think of it, as in our random way we supply ourselves with 

 such food as we fancy, some of which is siTre to be required for its use, 

 and to be eventually incorporated into its tissues, by the aid of an 

 unseen, unfelt hand, whose delicacy of operation surpasses our thought. 

 And with what may seem to us a certain prodigality, we must reflect 

 that He has also bestowed this same beautiful and complicate appara- 

 tus not only on the wildest of savage men, but likewise on many of 

 the higher animals, " brutes that perish," and with the same fond, 

 all-embracing care, preserves it for them in order during their lives. 



If you were to tell a thoughtful man, who happened to be quite 

 ignorant of the mechanism and action of the voice, that there were 

 living beings who endeavored to express their wishes, thoughts and 

 feelings merely by the aid of mechanical vibrations, thus causing the 

 particles of the air to swing, like invisible pendulums, backward and 

 forward, in certain ways, your listener would be impressed by the 



