CoiiJlruSi'wn of an Air Pump ivithout the Lower Valve. 127 



is foldered, that conveys the air from the valves to the du£l going under the valve pump, 

 as may be feen in Figure 8 ; o is part of the faid dud ; p is the joint funic into a 

 focket in the crofs piece Pi', which coiineds the cifterns, and has a dud through it leading 

 to them. Into this duft open the dufts q and r, the firfl; leading to the gauge in front of the 

 pump, the other to the cock and receiver. 



The other barrel is left out of the figure to fliew fome of the parts more diftiniSHy, ex- 

 cept Q, which is the top of the barrel retained and brought down out of its place to (hew 

 the top plate that fhuts up the barrel, feparatcd from the box which contains the collar of 

 leathers. 6 fhews one of the holes in the plate over which the valve lies, and which is 

 covered by R in the crofs piece. VV is the piiton fliewing the valve open on the top, 

 which is to prevent labour when the pump condenfes. WX is the ciftern, in which is 

 more diftinaiy feen the ilioulder for the leather which clofes the point between this and 

 the barrel, and alfo the focket iii which the oil lies over the leather. YZ is the condenfing 

 gaupe, with the orifice of the tube raifed above the furface of the quickfilver. e e is the col- 

 lar of leathers, through which the glafs tube moves, i is a fmall pipe coming up through 

 the quickfilver to make a communication between the valves and the gauge. 



Fig 7. is a view of the upper furface of the top plate which clofes the barrel, being 

 foldered into it, fhewing the place of the valve over the three fmall holes, one of which only 

 can be feen at S in f ig. 3 . 



Fig. 8. is a perpendicular feftion of the bottom piece, pipes, valve pump, cock, &c. at 

 right angles with the other fedion. Fig 6. AB is the pipe between the barrels, as repre- 

 fented in Fig 6. The button o is here fcrewed into the top inftead of the gauge. CD 

 is the valve pump and its ciftern, e the place of the valve under the cap. EF the cock 

 fhewing the duft through it leading to the atmofphere. GH the pipe leading from it to the 

 ftem of the receiver plate, in which is the cock I, to fhut up the dud when the plate is 

 ufed as a transferer. KK is the plate. L, a piece to {hut up the hole, into which tubes 

 &c. are occafionally fcrewed to perform experiments without removing the plate. The 

 clotted line at O fhews the place of the fcrew which prefles the plate againft the pipe : PO 

 the pipe and common gauge Handing in front of the pump. 



Fig. 9 is a horizontal feftion of the cock, and pieces containing the du£ls leading from it 

 to the receiver, the cifterns, and the valves on the top of the barrels. AB the duft con- 

 nedling the cifterns together. CD the duft leading from the cifterns to the cock. GH the 

 dua leading from the cock through the pipe AB (Fig. 8.] to the valves. DE the duft 

 through the cock, which occafionally conne£ls the two laft mentioned dufts with the duft 

 EF, leading from the cock to the receiver. I, the duft in the cock leading to the atmo- 

 fphere, which, when connefted with the duifl at D, lets ths air into the cifterns and bar- 

 rels for condenfation ; the other dud through the cock at the fame time conneding H .ind 

 I"-. Thisduft alfo, when conneiled with E, reftores the equilibrium in the receiver. KL 

 IS part cf the duft leading from the cifterns to the gauge. The dotted circles ftiew the 

 places of the pipe and valve pump onthe piece, and r the place where the air enters the 

 valve pump from the du(fl GH, and is thrown into the atmofphere when the pump ex- 

 haufts. 



Fig. 10. (hews the under furface of the boxes which contain the collars of leathers with the 

 croft piece which connefts them together, having a duel through it, as reprcfented by the 



a dotted 



