( 6;i )

Eet the Distance os Verjalllcs, as M. Nuis suppofeth, be iigco Foof,and the Capacity ös each Recept ack be about one half os a Cubick Foot :

I might make the Wheel with the Axis to malte their Revolution in one Mi-nute of Time, and lb Order all Things that the Air under the AfcendingPlug: might corste to be Rarisied to dich a degree that by its Elassicity itmight nöt Coutlterpoise more than 7 Foot of Water ; but at the fame timethe Air in the Rcc'ptacles A, A, B, B, would, even in its greatest Dilatation,be able to Countcrpoise 17 Foct: so it is plain, that the Air will be drivenfront the Recept rief es into the Pumps by a Strength equivalent to 10 Foot ofWarer : Now if we Compute the * Velocity of Air driven by soch a Pressure : vid.Suf.caf.y»-we (hall find that the said Velocity will be about 740 Foot in a Secotid : so §• xn -that in half a Minute, du ring which the Plug geeth up, this Air might paßabove 2.2.000 Foot, although it werc not Rarisied at all; but being Rarisied,as we do suppose it to be, it might go a great deal further.

I muss now take notice, that according to the Honourable Mr. Boylci Ex-periments, the RnrefncUon of the Air is niuch lesser than Mr. Nuis takes it tobe: for the Water contained in the Pipe N O, is so far front causing the Airto sil! up a {pace four times bigger, that it will not Extend it seif to L Spacaonce bigger than before ; Conhdering therefore the Velocity of the Air, andthe fnwll Dilatation it doth Risset, if any one will take the trouble to Com-ptite, he will sind, that if the Pumps have in Diameter the Diagonal of aSquare Foot, and the sime Height: and if the sinall Tubcs of Commutiicationbe made of f part of an Inch in Diameter j so that being 1 2000 Foot long,they may contain about one Cubick Foot of Air, that would be more than Suf- •ficient to make the neccsiary Raresatlion in the Rcceptadcs.

. But for the goed Succels of the Engine it is not enough to make the Air paßfront the Receptaclcs into the Pumps , it muss also Return front the Pumps intothe Rcccptacles .- Now for this Intern it would be necessary to sct the Recepta -des but five Foot above one another ; so, to Drive the Water up the PipeNO, it would be enough that the Air in the Rcceptade B, ssiould Preß wkha llrength Equivalent to 13 Foot of Water: For it is plain, that five Footin the Pipe NO, together wich a Pressure Equivalent to 17 Foot, which Ihave supposed to be in the Upper Recept aclc A, will make but 2.2. Foot in all;and therefore 2.Z Foot Pressing in the Receptaclc B, muss prevail, and causethe Water to Alcend : Now the Pressure in the Receptaclc being but 2.Z Foot,and the Air in the Pump Returning to its Ordinary Pressme, which is aboutZZ Foot, it is plain that the Air going back to the Receptade will be Drivenby Strength Equivalent to 10 Foot, as well as it had been in coming fromthe Reccptacle towards the Pump .- and (0 die Bigncls assgned for the Commur.i-cetien Bipes Will also pröve more than sufficient to sssss Effect.

From what I have been faying, it is plain, That in great Dissances thereIhould be made as many Pusnps as Rcccptacics, as hath been already pro-pounded : and for to Raiso Water but 60 Foot High, there ffioulci be re-quired 1 3 or 14 Recept aclcs, and as many Pumps of the Bignels -.forefissd.

Some People may take. this for a great Difficulty. But I Answer, That in