64 UNIVERSITY OF MISSOURI STUDIES 



upper positions. At B, the first thirty-one of them are at 

 their lower limits. At C, the stirrup has caused eleven 

 sections to assume their upper limits. From C to D, 

 the stirrup moves inwards through fourteen units of space, 

 pushing down the eleven sections which were up at C, leaving 

 the following twenty unmoved since they are down already, 

 and pushing down three more, so that now the first thirty-four 



Fig. 22. The combination 4 and 9 



sections of the partition are down, six further sections are up, 

 and all the following ones are in their normal positions. From 

 D to E the stirrup makes an outward movement through 

 thirty-three units of space, moving up the first thirty-three 

 sections of the partition. From E to F, the stirrup moves 

 inwards through twenty-three units of space ; and so on. At 

 S, we find the partition in the same position as at A, our 

 starting point; then, a new period begins. 



Let us now try to interpret the figure. We can easily 

 see that the first eight sections move down and up again nine 

 times during the period. This would mean 

 Do we hear 9? that the nerve ends located on this section 

 convey to our mind the sensation of the 

 tone 9 of the relative intensity eight. The ninth section of 

 the partition moves down and up only eight times during the 

 period ; but after our discussion about the omission of stimuli 



