[ *54 1 
But as for the manner and by" what means thefe 
Water-Bellows are fit to blow the* Fire, and to per- 
form the fame as Leathern or Wooden Bellow s, there 
is no other Reafon, but the very felf-fame wherein 
the Effed of the ordinary Bellows confifts. For an 
ordinary pair of Bellows blow for no other Reafon, 
but that the Air, which enters the Bellows , and which 
they contain when raifed, is again comprefled or forced 
into a narrower Space, when the Bellows clofe : Now 
fince the Air, like all other Fluids, moves to that 
Place where it meets with the lead Rcfiftance, the 
Air muft confequently go through the Opening which 
is left for the fame, with a Velocity proportioned to 
the Force by which the Air is comprefled, and muft 
of neceflity blow ftronger or weaker, in regard to the 
Velocity by which the Top and Bottom of the Bellows 
meet % theBlaft alfo will laft inProportion to theQuan- 
tity of Air, that was drawn into the Bellows through 
the Valve or Wind-clap. 
This does after the fame manner happen in our 
Water-Bellows s for the Air, which they contain, 
cannot force itfelf down through the Water more 
than though a well-fecured Deal-board with Pitch $ 
^hen the Bellows are lower'd down into the Water, 
* the Air which they contain muft neceflarily be com- 
prefled by the Water, which rifes alternately into 
the Bellows A and A ; fo the Air muft recede and go 
through the Leathern Tubes R, R, where the Air 
meets with the leaf! Refiftance. From all which it un- 
doubtedly follows, that the larger, that is to fay, the 
more Air thefe Water-Bellows are made to contain, 
and the greater the Velocity is by which they are made 
to defcend into the Water, fo much greater is 
their 
