298 The Natural Hiflory 



If it be ask, why, when DE is touchton Xor Z, whereby the 

 conterminous parts feem principally to be moved, CD does not 

 vibrate, which is Vnifon to it. He anfwers, that if all CD could 

 tremble, then beating the Air back again on DE, it would at once 

 fhake DZ and XE (Vnifons to CD) as in the former Prof of. QJL.A'. 



Prop. 6. If the kffer of two twelfths IK, Fig. 12. be touched, 

 each third fart of the greater, Ka, a b, b L, will move ; but 

 in the dwifions, a b fiandfiill. On the contrary, if the 

 greater be touched en its parts, K a, ab, b L, all the lefs will 

 tremble ; but if on the divifions a b, it will not fiir. 



Experimentum (sr Demonfiratio ut ante, IK. being a Vnifon to K a, a b, 

 b L,perPrincip. 2. 



Prop. 7. If the kffer of two fifteenths, MN Fig. 1 3. be touched, 

 the greater will move in all its quarters N c, c 4, 4 d, d O, 

 but not in their divifions, c 4 d. On the contrary, if the 

 greater be touched on either of its quarters N c, c 4, 4 d, d O, 

 all the lefs will move ; but if on the divifions c 4 d, it will 

 fiandfiill. 



Experimentum & demonflratio infiituuntur ut fupra. MN being 

 Vnifon to Nc, c4, /[.d,dO, per Princip. 2. 



207. Thus having cleared the late obferved Phenomena men- 

 tioned above in . 199. he infers the following Corollaries. 



1 . That all Confonancy Cor Sympathetick. motion of firings J 

 is made by Vnifons, that is, 1 moves 1, and noti. 2, or 2.3, 

 isre. as appears from the fore-going Proportions. Hence 



2. That each firing at the due touch of another, will tremble in 

 as many places as it contains Vnifons thereunto, whether to 

 the whole or its parts. So a lower oftave in 2, each half be- 

 ing Vnifon to the higher ; a lower fifth in three, and the 

 higher in two, they being as 3 Vnifons to 2, irc Hence 



3. That all tuned firings whatever C whether thirds fourths,fifths, 

 fixths, i&c.) will anfwer each other more or lefs, at the due 

 touch of their Correfpondents : But the tremor or vibration 

 in fome of them being made in many places at the fame time 

 ( according to the number of the Vnifons, per Corol. 2 .J and 

 therefore not great, where the part moved is but (hort (per 



Caf 1. Hyp. 2. Princ.i.) it cannot always be difcerned by 



the 



