76 



ON THE PHYSIOLOGICAL CAUSES OF 



of time, and being consequently an octave higher in pitch. and D, 

 on the other hand, represent the waves which result from the super- 

 position of B on A. The dotted curves in the first halves of and D 

 are repetitions of so much of the figure A. In 0, the initial point e 

 of the curve B coincides with the initial point d of A. But in D, 

 the deepest point b. 2 of the first hollow in B is placed under the 

 initial point of A. The result is two different compound-curves, the 

 first C having steeply ascending and more gently descending crests, 

 but so related that by reversing the figure the elevations would 

 exactly fit into the depressions. But in D we have pointed crests and 

 flattened hollows, which are, however, symmetrical with respect to 

 right and left. 



FIG. 10. 



Other forms are shown in Fig. 10, which are also compounded of 

 two simple waves, A and B, of which B makes three times as many 

 vibrations in a second as A, and consequently is the twelfth higher 

 in pitch. The dotted curves in C and D are, as before, repetitions of 



