124 COSMIC PHILOSOPHY, [pt. ii. 



sound is at first faint, then gradually becomes loud, then 

 grows fainter, till it disappears. Now, note what happens 

 when elementary sounds are made to succeed each other. 

 If the succession be irregular, there is a mere chaos of 

 noises — a case with which we need not here deal. But if 

 the succession be regular, and steadily increase in rapidity, 

 there follows a remarkable series of results. As long as the 

 waves or pulses answering to the elementary sounds succeed 

 each other slowly, the sounds are distinguishable from each 

 other as raps or puffs, according to the instrument employed, 

 and each has its maximum and its two minima of intensity. 

 But, when the waves begin to strike the ear at the rate of 

 about sixteen in a second, the consciousness of separate raps 

 or puffs becomes evanescent, and there arises the conscious- 

 ness of a continuous tone of very low pitch. That the con- 

 sciousness of the separate sounds has not quite ceased, and 

 that the continuousness of the tone which they compose is 

 not complete, are shown by the fact that the maxima and 

 minima are still perceived. In the deepest bass-notes of an 

 organ, for example, the pulsations are clearly distinguishable 

 — a fact which proves that we are conscious of the effects 

 answering respectively to the protuberances and to the 

 hollows of the waves. Now, the pitch of a tone depends 

 upon the rapidity with which the waves succeed each other, 

 and, therefoi-e, upon their length, or the distance between 

 two successive hollows, because as the waves come faster 

 they grow shorter. The shorter the waves, the higher the 

 pitch. Hence, as the pitch rises, the protuberance of any 

 wave approaches nearer and nearer to the protuberances of 

 the waves immediately behind it and in front of it, and the 

 maximum intensities of sound which answer to the protuber- 

 ances become crowded together in consciousness. The result 

 is that, after a while, the maxima and minima are no longer 

 distinguishable by the ear, so that by no effort of attention 

 can we discern the elementary pulses of which the tone is 



