( j6o ) 
The found is folike as not tobeeafily diftinguifhedby 
the nicefl Ear, and as it performs the very fame Notes, fo 
it has the fame defefts as a Trumpet, for if the String 
beftop'd in any part, butfuchas produces a Trumpet 
Note^t yields a harfh and uncouth (not a Mufical) found. 
Let us therefore proceed toourfirft inquiry, and ex- 
amine what is the reafon that the Trumpet-Marine will 
perform no other but the Trumpet Notes. 
It is a known Experiment of two Unifon Strings, that 
ftriking one of them moves the other, which- probably 
proceeds from hence, that the impulfes of the Air which 
are made by one String, do more eafily fee another in mo- 
tion which lies in a difpofuion to have its vibration Syn- 
chronous to them, than a third whofe motion would be 
crofs. 
We may improve this a little farther, by obferving 
that a String will move not only at the ftriking of a Uni- 
fon, but an 8ch. or 12th, though after a different manner. 
If a unifon is ftruck, it makes one in tire vibration in 
the whole String, as in Fig. A, and the motion is moft 
fenfible in the middle at m, for there the vibrations take 
the greateft fcope. 
If an 8th. is ftruck, it makes two vibrations, as in 
Fig. B, and then the point m is in a manner quiefcent, 
and the moft fenfible motion at n, n. 
If a 1 2th. be ftruck, then it makes three vibrations, 
as in Fig. C 9 and the greateft motion at q, m> y, and hardly 
to be perceived at All which may be plainly experi- 
mented by putting a little piece of paper upon thefe- 
veral parts of the String to make the motion more con- 
fpicuo us. 
So that in fhort this Experiment holds when any 
Note is ftruck which is a unifon to fome aliquot part of the 
String, as in the former Examples, an 8th. is unifon to 
half the String, and a 12th. to a third part of it. 
In 
