ap^ Wi Statural Hijlory 



and formation of />or, as was fuppofed . 24. of thefirft ,6<2~ 

 /fer of this Book. Whence alfo 'tis equally cafie to make thefe 

 three following Illations* 



it That firings agreeing in either lengthy bignefs, or tenfwn, can 

 be made unifons but four ways. 1 . If they be of the fame 

 length, bignefs, and tenfwn Cper Caf.i. Hyp.i.J 2. Of the fame 

 length, and one a cize and tenfwn equally greater than the o- 

 ther (per Caf^.HypA.J 3. Of the fame cize, and one a length 

 and tenfwn equally greater (per Caf. 2. Hyp. 2. J 4. Of the 

 fame tenfwn, and one as much longer as 'tis left (per Caf. 5. 

 Hyp* 2.) and after the fame manner when they difagree in 

 ail three, as will be obvious to the confidering : Wherefore 

 unifons are always firings of the fame, or a proportionable 

 length, bignefs, and tenfwn. 



2. That unifons may be moved by the fame force, in the fame 

 time ; or being moved by the fame or an equal force, will 

 vibratein the fame time ; as is manifeft in the fore-mention- , 

 ed Cafes, to which all others bear Analogy. 



3, That oclaves being moved by the fame or an equal force, the 

 upper will vibrate in half the time, that the under does, or 

 twice to its once Qw Caf 2 is 3. Hyp. 1 . is- Caf 1, 6, 7, (y 

 9. Hyp. 2.J wherefore they can by no force be made to vi- 

 brate together ; for as much as the fame firing (being of the 

 fame length and tenfwnj always vibrates in the fame time ; a 

 greater force only making it fly out to a greater difiance, or 

 fetch a greater compafs in its vibrations, and thereby move 

 (but not vibratej falter, />er Concluf. posl Prjemiffa*. And 

 thefame is verified concerning all other Notes. 



205. Having done with his firfi Principle, with the Hypothefes, 



and feveral Cafes attending it, the fame Reverend and Learned 



Dr. N. M proceeds to his fecond Principle, viz. That all tuned 



firings either are or confifi of unifons, which will plainly appear from 



thedivifionof the Monocbord ; where, 



1. Vnifons are as AB to BC, Fig. 6. 1 to 1 part, or vibration, per 



Illationemi. iy 2. 



2 . A Diapajon or Oclaves, as BCto CD, Fig. 7. 1 to 2 Vnifons, or 



2 to 1 Vibrat.per Illat. 3. 



3. A Diapente, or perfect fifths, as CD to VE, Fig. 8. 2 to 3 

 Vnifons, or 3 to 2 vibrat. 4. A 



