On RYTHMICAL MEASURES. 71. 



movement, or fufpend the flow of the units, during a time 

 which is either indeterminate, or of whieh we take no exaft 

 account, and proceed afterwards as if no fuch paufe had been 

 made. Thefe ad libitum paufes, as they are called in mufic, 

 are feldom taken into the meafure, or confidered as making any 

 part of it. The intention of them is to roufe and flrike the 

 mind of the hearer ; and there are various occafions on which 

 they may be introduced with very happy effedl. Modern mu- 

 ficians often ufe them as opportunities of difplaying the extent 

 of their invention and execution, when lofing fight of the 

 compofer, giving the reins to their fancy, and little regarding 

 rule or meafure, they entertain their hearers with a feries of 

 rapid divifions through the whole compafs of their inftrument, 

 and of uncommon and irregular modulations. But farther, 

 we can not only fufpend for a time the courfe of the rythmical 

 movement in the manner above defcribed, we can alfo render 

 it occafionally flower or quicker, by increafing or lefl'ening the 

 dimenfion of the unit, when we wifh to exprefs a heavy lan- 

 guid movement, or one that is light and animated ; and after 

 having executed a part of the fucceffion in that manner, we 

 can often, with great accuracy, refume our firft unit, or re- 

 turn to our original time. We probably do this with mod cer- 

 tainty, when this enlargement or diminution of the unit is 

 made in fome fenfible proportion, as that of two to one. This 

 practice, and the effedls of it, were well known to the an- 

 cients. They made it a branch of their rythmical inftitution, 

 under the title of Ayuyri pv6f/.ix^, or Du£lus Rythmicus. 



In mufic, the accented note, or beginning of the meafure, 

 is not always the firft note that is founded j it is often preceded 

 by one or more feeble notes, which are placed before the bar 

 or perpendicular line which marks the commencement of the 

 firft meafure. Thefe introdutftory notes are thought to give a 

 foftnefs and delicacy to the opening of the piece. In regular 

 mufic, when the parts are repeated, the time of thefe notes 



is 



