346 



DR. KCENIG'S researches ON 



less this arises from the greater true intensity of the sounds of higher 

 pitch. With the object of pursuing this matter still more closely, Dr. 

 Koenig constructed a series of 12 forks of extremely high pitch, all 

 within the range of half a tone, the lowest giving sU and the highest 

 lit-. The frequencies and the beats and beat-tones given by seven of 

 them are recorded in Tabl**. iir. 



Table III. 



The first of these intervals is a diatonic semitone ; the second of them 

 is a quarter-tone; the third is an eighth of a tone; nevertheless, a sen- 

 sitive ear will readily detect a difference of pitch between the two sep- 

 arate sounds. The last of the intervals is about half a comma. 



These forks are excited by striking them with a steel hammer. Some 

 of the resulting beat-tones will be heard all over the theater; but, in 

 the case of the very low tones of 40 and 32 vibrations, only those who 

 are close at hand will hear them. The case in which there are 2C beats 

 is curious. Most hearers are doubtful whether they perceive a tone or 

 not. There is a curious fluttering effect, as though a tone were there, 

 but not continuously. 



We have seen, then, that the beat-tones correspond in pitch to the 

 number of the beats; that they can themselves interfere and give sec- 

 ondary beats; and that the same number of beats will always give 

 the same beat tone irrespectively of the interval between the two pri- 

 mary tones. What better proofs could one desire to support the view 

 that the beat-tones are caused, as Dr. Young supposed, by the same 

 cause as the beats, and not, as von Helmholtz maintains, by some 

 other cause? Yet there are some further points in evidence which are 

 of significance and lend additional weight to the proofs already ad- 

 duced. 



Beats behave like i)rimary impulses in the following respect, that 

 when they come with a (re<iuency between 32 and 128 i)er second, they 

 may be heard, according to circumstances, either discontinuously or 

 ]>len(li:ig into a (tontiiiuons sensation. 



It has been objected that, whereas beats imply interference between 

 two separate modes of vibration arising in tw^o separate organs, combi- 

 nation-tones, whether summational or differential or any other, must 



