VOL. XL.] PHILOSOPHICAL TRANSACTIONS. IQ3 



pressure of the air within, when they sink down into the water. On the same 

 heads are two pliable leathern tubes k, r, fixed one at the top of each water- 

 bellows, which tubes are made and prepared in the same manner as those used 

 in water-engines for extinguishing fire. These leathern tubes, or pipes, reach 

 from the bellows, to wooden tubes t, t, which carry the wind into the iron 

 furnace m, or any other place desired. 



These bellows are also provided with iron chains k, k, fastened to two sweeps 

 s, s, by which means they hang perpendicular from the beam of the balance, 

 and at the same distance from the centre of its motion c. 



On the balance are two sloping gutters f, f, into which the water alternately 

 runs from the gutter g, and so give motion to the whole work ; so that these 

 last-mentioned gutters f, f, do the same service as an over- shot, or any other 

 water-wheel, and cost a great deal less, but give as even and regular a motion, 

 as any pendulum, for measuring time; for as soon as so much water runs 

 into either of the aforementioned inclined planes of the gutters, so that the 

 momentum of the water exceeds the friction near the centre of motion c, the 

 gutter immediately moves down with a velocity increasing, till the balance 

 meets with the resistance of the wooden springs h, h, and at the same time 

 raises the opposite water-bellows, or that bellows which is fixed under the op- 

 posite gutter. In the same moment again as the said gutter begins its motion, 

 being come down on the spring, and delivers all the water it has received ; at 

 the very same time the water begins to run into the opposite gutter, which re- 

 ceives its load of water almost as soon as the former is emptied ; so that one of 

 the gutters does its effect, as soon as the other has done his, and this alternately 

 one after the other. 



These sloping gutters, on the balance, do therefore all the service and efl^ect 

 which a water-wheel does in working the ordinary bellows, and that by means 

 of the power which the water applies to the wheel of giving the ordinary bellows 

 their motion, after the same manner does the water here empower the sloping 

 gutters to do the same work. 



But as to the manner and the means by which these water-bellows are fit to 

 blow the fire, and to perform the same as leathern or wooden bellows, there is 

 no other reason, but the very same in which the effect of the ordinary bellows 

 consists. For an ordinary pair of bellows blow for no other reason, but that 

 the air, which enters the bellows, and which they contain when raised, is again 

 compressed or forced into a narrower space, when the bellows close : now since 

 the air, like all other fluids, moves to that place where it meets with the least 

 resistance, the air must consequently go through the opening left for it, with a 

 velocity proportioned to the force by which the air is compressed, and must 



VOL. viii. C c 



