xpS The 3\(^mral Hiflory 
Tf it be askt, why, when DE is toucht on 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 ^ir back again on P£, it would at once 
lhake DZ and XE (Vnifons to CD) as in the former Prof of, Q^E,A, 
Prop. 6, If the lefer of two tmlfths Fig. 12. he touched^ 
each third part of the greater^ K a, a b, b L, will move ; hut 
in the divifions^ a b fiand ftilL On the contrary, if the 
greater he touched on its parts^ K a, a b, b L, all the lefs will 
tremhle ; hut if on the divifions a b, // will not flir, 
Experimentum ist Demonfiratio ut ante^ IK being a Vnifon to K a, a b, 
b L, per Princip. 2 . 
Prop. 7. If the kffer of twofifteenths^UN Fig. 13. he touched^ 
the greater will move in all its quarters N c, c 4, 4 d, dO, 
hut not in their divifions^ c 4 d. On the contrary, // the 
greater he touched on either of its quarters N c, c 4, 4 d, d O, 
all the lefs will move ; hut if on the divifions c 4 d, it will 
fiand ftilL 
Eocperimentumisr demonfiratio infiituunturut fupra. MNht'mg 
Vnifon to Nc, c4, ^d^dO^ per Princip, 2. 
207. Thus having cleared the late obferved Phd^nomenamm" 
tioncd above in §. 199. he infers the following Coro//^ria. 
1 . That all Confonancy (^or Sympathetic^ motion of firings J 
is made by Z^wi/ow^, that is, i moves i, and not i. 2, or 2,3 ^ 
isfc, as appears from the fore-going Propofitions, 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 o5iave 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, isrc Hence 
3. That all tuned firings whatever ( whether thirds/ourths^fifthsy 
fixthsj isrc.) will anfwer each other more or lefs, at the due 
touch of their Corre/pdndents : But the tremor or vibration 
. in fome of them being made in many places at the fame time 
C according to the number of the Vnifons ^per Corol. 2. J and 
therefore not great, where the part moved is but (liort (per 
Caf I . Hyp, 2. Princ. i.^ it cannot always be difcerned by 
the 
