Pneumatics.

piston. These Holes in the Pistons and°stoms of the Barrels are cover’d with

193

Bi

a Res, to prevent the Return of the Air in-*° the Receiver. 111 is the Mercurial Gage,common Barometer, immersed in a Ba-0l t of Mercury m m fix’d in the Bottom ofFrame, and at Top communicates withReceiver, which therefore strews how^tich the Receiver is exhausted by the Ris-§ of the Mercury . in the Tube, by a^ ra duated Scale affixed thereto. The Stop-Co cb n a jf 0j communicates with the Re-^ lVe r* and consequently with the Swan-and Mercurial Tube : Its Use is, bylUr ning the Cock, to re-admit the Air,^en there is Occasion. The Receiver is^ r ° u nd true on the Bottom, and is fixed^ the Pump at first by means of wetted. ’Others to exclude the Air, instead of Ce-eil t formerly used for that Purpose..

^ L: t with how much more G'onveniency,^ less Expence, Pneumaiical Experi-E^ts of all Kinds may be perform’d, byElegants and Portable Air-Pump ,

; . lc o I have lately contrived and made,be easy to apprehend from a bare View^ the Figure thereof: In which AB is■fete or Part containing the Wheel,^h alternately raises and depresses the"ol. II. O Pistons

Plate

XXIi.Fig- 5*

Vc