of eha cavern of the internal part of the Ear^alternately goes 
and comes through its knot-like paflage , and fprcads it fclf 
through the other wayes of the fpuogy like boiie^and being 
repercuffcd to the webs that clofe it, rebounds and multiplys 
thefouqd* Another parcel of Air follows, andftrikcs the 
drum again, and caufeth the (haking as before* 
But if the Ear be withia two Sonorous Spheres, theaficft- 
edpuifes that eaufc the found, do fucceed the one amidft 
the other, by turns, to ftrike the outward drum ^ and by the 
exigences of the alternations , the ration's that are not expre- 
flible by numbers become to be (b,and that both offuch num- 
bersjas can be diftributcd amongft the particles of theAir^W 
of foch alternations^as that amongft the ftrooks, the (bakings 
of f he drum may be all numbred.And the Ibul perceives the 
numbers of thtfe alternarionsj and the numbers of the fliak- 
ing« of the drum amidft the ftrokes cf the two fouuds: And 
wbilft the aura that is afFedcd by the two founding bodies , 
does communicate witbthe aura between the drums ftic there 
takes alfo notice of the Logarithme of the ration of founds , 
and commcnfurates it with the Logarithmcsof ther^//W/ 
ihe doable, and its half * 
Now, for as much as the Soul pleafcth her felfwith two 
founds together, and with the fucceflion of many fouads one 
afte r an other^that occur so one Song/cis neceffary ftieftould 
comprehend in the Senfe thefe three things which fbc per- 
ceives, without any abftradion of the Mind^ The numbers of 
the alternation moft needs be eafy to make , and two in one 
fole numeration* The commenfuratioo of the Logarithmes 
muftbemadeby the way of an eafy divifion into parts, and 
into a number of parts eafy to be oumbred. 
And becaufe it is not poflible precifely to accord thefe two 
tjfiogs equally/ome crrours muft needs happen,which may be 
all perceived by Reafon^ but cannot all be alike taken notice 
of by Senfe : Some are inferifible/ome altogether intolerable 
md abfurd, others between both 5 and ofthcfe/ome arenea. 
rcr to the infcnOble ones ; others, tothofethat are intolera- 
blc : Of which errors, convenient eftimates are given, and ac- 
cording: to tiiedifiitences of thofe errors the ration^ of 
foundi^ are diftipgoiili'to., 
Laftly, 
