(68) 
cord of them to each other : And from the continua- 
tion of the motion the fame as to time till it ceafe is 
the caufe of the continuance of the Tone the fame. 
This Dodlrine he explains by the Pendulum and other 
ftnfible vibrating Motions, as firings or Springs : From 
which vifible Phenomena he concludes, that the Motions 
that caufe Mufical Sound are of the fame Nature, tho' 
they cannot be diftinguiflit by the fight. And in an 
Appendix to this Chapter he has farther explained the 
Dodrine, and refblved fome Doubts and Objeftions con- 
cerning it ; and more particularly applies it to the ex- 
plication of the tenfionjength, vibration, and velocity 
of Mufical firings ; (hewing that as fhorter Pendulums 
and ftronger Springs make quicker Vibrations, fo (hor- 
ter ftrings,and more ftrongly tended, make acuter Notes. 
In the Third Chapter he fpeaks in general of Confo- 
nancy and Diflbnancy, {hewing it to be the Refult of 
the Agreement or Difagreement of the undulated Mo- 
tions of the Air, which he explains by the undulations 
on the Surface of Water or Quick-filver, though he 
doth not inftance in them as exaft to his purpofe, but 
only as Illuftrations ; to which purpofe he alfo mentions 
fome Experiments of the Agreement and Difagreement 
of fome Mufical founds as they are made in the Air , 
which are more remarkable and notorious, and do very 
much pleafe, or very much offend the hearing, explain- 
ing the Rcafons of them by the fame general Doftrine. 
In the Fourth Cliaprer he more particularly (hews and 
determines what the Harmonious Sounds which pleafe 
the Ear ( which is the Judge) are, and therein (hews 
th t the Ear approves of thefe Intervals, i. e, the 8th. 
the 5th. the 4th. then of the 3d. major, the 3d. minor, 
the 6fh. major^ the 6th. minor; and of greater Intervals 
compounded of thefe with an 8th. as ot a roth, which 
is an 8th. and a 3d. of a nth. which is an 8th. and a 
5th. of a 15th. which is an 8th. and an 8th, tgc. This 
Syftem 
