518 Dr. R. Konig on the Simultaneous 



In making these experiments we can, as usual, strike the 

 forks with a bow ; but as in consequence of their high pitch 

 there is no longer any fear of the formation of partial notes, it 

 is often more convenient to strike them with a steel clapper, 

 as this moves more quickly, and the note of the fork first 

 touched has not then lost much of its intensity when the 

 second note is produced. 



All the clangs given in this Table allow the rattle (or, 

 as it is better termed in these high notes, the whir) of the beats 

 to be heard simultaneously with the beat-notes, which latter 

 are more powerful according as the tuning-forks are struck 

 harder. If we wish to hear the whir of the beats alone, we 

 have only to remove the two forks a little further from 

 the ear ; the beat-notes, however, cannot be distinguished 

 quite alone, even if we place the forks close to the ear ; we 

 cannot even quite succeed in doing this with the notes 7936 

 and 8192 v. s., although with these the beat-note c is extremely 

 powerful. 



We see by these experiments that with sufficiently power- 

 ful primary notes, not more than 32 beats are necessary to 

 form a note, that further beats to about 128 can be distin- 

 guished in intervals of any extent that may be wished, and 

 that between 32 and about 128 beats in the second the beats 

 and beat-notes can be heard together. The question now is 

 whether this is the same result which we obtain also with 

 primary impulses. 



It is known, in the first place, that 32 primary impulses can 

 form a note; and we might expect, on the other hand, that the 

 ear should be capable of perceiving more than 100 impulses 

 in the second, even from the old observations, according to 

 which it can perceive the difference of movement between two 

 pendulums which do not diverge from isochronism by more 

 than the hundredth part of a second. It was to be supposed, 

 indeed, that if the ear could receive two distinct impressions 

 only y^Q of a second apart, it could also perceive a whole 

 series of such effects with similar distances ; but this experi- 

 ment can also be very well directly made with a cog-wheel. 

 That which I used is of wood, 35 millims. thick, 36 centims. 

 in diameter, and with 128 teeth. If we press a small spring 

 board of hard wood very strongly upon these teeth, we hear 

 through the constantly increasing rapidity of rotation the first 

 hardly perceptible beats change to a rattle, which is still 

 clearly perceived when the wheel revolves once in the second, 

 and consequently the number of strokes has attained to 128. 

 Besides this rattle we can also hear, however, if the single 

 strokes are not too powerful, the note c (256 v. s.). If we re- 



