( 4 « > 
Ring c, by an individual Action, and comptefs it 
likewife in Proportion to the Difference of the 
Forces, and fo on in the other Ring?. So that 
the Compreflion of the laft Ring or Body is to be 
look’d upon as it were like a Subfiance or Body 
put into Motion, which continues in Motion, ’till it 
meets with fomething elfe, that makes an equal or 
fufficient Refiflance. 
From the Whole Mr. Gerjlen draws this material 
Propofition, that the Body a may after this manner 
acquire, by repeated Vibration?, a greater Expanfion 
in the Line AB, than it had before, provided the 
Series be long enough, fo that the Force impreifed may 
not be foon reflected. This Matter is treated of more 
at large in the following Propofitions, to the end of 
the Chapter. 
The fecond Chapter is an application of the 
'theory deliver’d, to the Solution of the Phenomena 
of the Barometer, after the following manner. The 
Particles of Air, fays Mr. Gerjlen, however unknown 
in other refpe&s, are very well known to be capable 
of receiving and propagating tremulous Vibrations : 
From hence it follows, as alfo from fome Prin- 
ciples of Sir Ifaac Newton, that the Air (as in 
Prop. V ) may be dilated by repeated tremulous 
Vibrations \ and by Prop. VJ, thefe Vibrations may 
be generated or produced by a confufed Motion of the 
Particles of the Air, or by the Agitation of a Wind. 
The Author in Prop. VII and VIII, undertakes to 
demonftrate, that the Dilatation produced by the 
Motion of a Wind, is lefs when the ambient Air has 
a Motion the fame Way, than if the Wind moved 
with 
