408 POPULAR LECTURES AND ADDRESSES. 



said still more unqualifiedly of the minor thirds, 

 the number of beats on E G being more than 

 seventeen per second. It does not seem easy to 

 explain on any physical or physiological principles 

 the decidedly agreeable effect produced on the ear 

 by a succession of major and minor thirds of 

 pianoforte notes. It is, no doubt, to the slowing 

 of the beats by the superposition of a third note 

 upon either of the binaries C E or E G in the 

 ternary combination C E G, because of its com- 

 paratively close approximation to C G E (for 

 which the beats are only five per second), that 

 the comparatively smooth harmoniousness of the 

 common chord in the tempered scale is due. 



It is not generally known how easily beats on 

 approximations to other harmonies than unison 

 arc heard, even when the constituent notes are 

 simple tones. Through the kindness of Professor 

 M'Kcndrick I have been allowed the means of 

 testing them in very varied combinations, by aid 

 of a scries of excellent tuning-forks of Koenig's, 

 each mounted on a wooden box resonator, after 

 the manner of Marloyc. For such experiments 



