334 PHILOSOPHICAL TRANSACTIONS. [anMO 1747. 



on the organ during the winding up of yy, will be written on the scroll by the 

 pencils b, c, d, &c. 



All the graces in music, being only a swift succession of sounds of minute du- 

 ration, will be expressed by the pencils by small hatches geometrically propor- 

 tioned to those durations. Ex. gr. 



A single beat _" 



A double beat _ ~- 



A shake ~ _~ 



A turn ~_ _ 



A single backfall "~ 



A double backfall ""— ~ 



A shake and turn '■ 



If a line commence exactly over or under the termination of another, it is an 

 indication of a slur ; as 



So a small interval indicates the contrary ; as 



Flat or sharp notes are implied by their situation on the red or faint lines ; the 

 natural notes being always drawn between them, viz. in the spaces. (See fig. 6.) 



The scroll may be prepared before-hand with red lines to fall under their re- 

 spective pencils. It is the surest way to rule them after ; though it is possible 

 to contrive that they may be ruled the same instant the music is writing. The 

 places of the bars may be noted by two supernumerary pencils, with a commu- 

 nication to the hand or foot of a person beating time. 



Grave music from brisk, slow from fast, &c. will be better distinguished by 

 this machine, than in the ordinary way by the words adagio, allegro, grave, 

 presto, &c. for by these words we only know in general this must be slow or fast, 

 but not to what degree, that being left to the imagination of the performer ; but 

 here it is known exactly how many notes must be played in a second of time ; 

 viz. as many as are contained in 1 inch of the scroll. 



Lastly, whereas, in the ordinary way of writing music, you have either no 

 character for graces, or such as do not denote the time and manner of their per- 

 formance, here you have the minutest particles of sound that compose the most 

 transient graces mathematically delineated. 



