1880.1 



Notes of Observations on Musical Beats. 



529 



reeds themselves was raised or not ; I think it was not. But the 

 nominal value, depending" on the accelerated beats- was, of course, 

 increased, and the experiment of the forks shows that it was increased 

 exactly in the ratio of the internal to the external beats. At any rate, 

 therefore, if the pitch of the tones was increased, it was not caused by 

 the confined air acting upon a single speaking reed, but was occasioned 

 by the joint action of two speaking reeds. 



This joint action was very powerful. It shook the whole instrument 

 violently. When reeds 256 and 260 (I cite them always by their 

 nominal value) were sounded together, at first only a crash was 

 audible, but after about a second the ear could distinguish the beating 

 of the two primes, closely resembling the beating of two tuning-forks 

 held over resonance jars, but accompanied throughout by a great crash, 

 which made the simple beats difficult to keep well in the ear. This 

 was totally different from the effect when a fork was substituted for 

 one of the reeds. The simple beats remained, but the crash dis- 

 appeared. Moving of the head caused considerable difference in the 

 loudness of the simple beats, due perhaps, to placing the ear at or near 

 a node of the sound wave, and removing it again. It was useless to 

 attempt to count the beats till these simple beats were well recognised. 

 As I ascended the scale, the crash became less. It was much less for 

 reeds 272 and 276, and the contrast of these beats with those of 256 

 and 260 on the one hand, and 288 and 292 on the other, was very 

 striking. For reeds 320 and 324 the crash was comparatively faint. 

 I could not distinguish the beats of the second partials or octaves from 

 the general crash arising from the beats of all the other partials. The 

 beats of the primes were quite separate, slow (4 in a second) and 

 distinct, and they seemed to give the time to the other beats. For 

 reeds 376 and 380, the beat of the primes overpowered the crash, 

 which became comparatively light, and after this point, the beats of 

 the primes were always easy to find. From reeds 412 and 416, the • 

 beats of the primes were the principal phenomena, and after 492 and 

 496, the beats were practically simple. 



In the tenor and bass tonometers, the beats were still more dis- 

 tressing to the ear, for even for single notes the upper partials beat 

 clearly and slowly enough, after reed 64, to be distinctly perceived as 

 beats ; and the beats of two reeds sounded almost like a continually 

 reiterated feu cle joie. Below reed 16, the primes could not be heard 

 at all, but down to 8 the beating upper partials could be heard. 



The effect of the external beats on the ear was distinctly different 

 from the effects of the internal beats. The surge of the other partials 

 was not so strong, and the beats were much easier to count. At one 

 time I placed the two tonometers fully 50 feet apart, and stood half 

 way between them to count the beats, which were remarkably clear, 

 the surge becoming indistinct, very like that of the distant waves on 



