6o On RYTHMICAL MEASURES. 



equal parts, the number of parts into which we adually can 

 divide it mufl depend upon the powers which we have of per- 

 forming quick motions. Thefe powers are very Umited. The 

 roll of a drum, the moft rapid movement of a mufician upoa 

 an inftrument, does not divide a fecond of time into much more 

 than fixteen or eighteen equal parts, hardly ever into twenty-four. 

 Our power of dividing a fmall interval of time, equally and 

 uniformly, and of perceiving fuch a divifion by the ear, is alfo 

 confined to certain proportions. The fimplefl: and the eafieft 

 divifion is into two, or any of its powers which are within the 

 limits of pra(5licability. We can divide an interval into two or 

 into four equal parts with almoft the fame eafe. Having ob- 

 tained either of thefe divifions, we can alfo confider each of the 

 parts as an unit, and fubdivide it into two or four, thus making 

 a divifion into eight, or, if our powers of quick motion will 

 admit, into fixteen *. Beyond this we cannot carry the powers 

 of two in the divifion of fingle intervals. The divifion into 

 three equal parts is not fo fimple as that into two. By practice, 

 however, it comes to be equally eafy. Having eftablifhed this 

 divifion, we can, as in the former cafe, fubdivide each of them 

 into twos, into threes or into fours, thus obtaining a divifion 

 into fix, nine and twelve. We alfo obtain the numbers fix and 

 twelve, by breaking down into threes each of the parts of a 

 divifion by two or four f . A divifion into five equal parts re- 

 quires a confiderable effort of the attention. W^e fometimes 

 meet with a fucceffion of fuch divifions in the works of mufi- 

 cians. In executing fuch pafTages, the performer, fixing his 

 attention upon the unit, probably runs on to the end of the 



fuccefEon 



* Eight is moft eafily conceived as two fours; fixteen is always conceived as 

 four fours. 



+ Six we can indifferently conceive as three twos^ or as two threes ; nine we muft coD- 

 ctlve as three threes; twelve we can either conceive as three fours or four threes) we 

 «an alfo conceive it as two fixes, but with more difficulty as fix twos. 



