t hap. 3.] The fucking Pumpj 45 1 



with a pipe of 'afpiratfion or lucking pipe F P adapted 

 to the lower part. At the union of this pipe with the 

 body of the pump is a fucker s> defigned to permit 

 the water, while the pifton is raifed, to enter through 

 the pipe of afpiration P F into the body of the pump 

 F E, and to prevent it, while the pifton is lowering, 

 from being difcharged the fame way. In the body of 

 the pump is a pifton L, made like that at I in PlateVII. 

 Fig. 3. and which it put in action in the fame man- 

 ner by the afliftance of the lever X Z Y. This pump 

 fhould be placed in fuch manner as to have only the 

 lower extremity of the afpiration pipe F P plunged 

 into the water. 



While the pump remains inactive, the two fuckers 

 S and s are naturally clofed from their own weight. 

 If the pifton L is raifed up by means of putting the 

 lever X Z Y in the fituation u Z y, the column of air 

 which refts above is elevated, and the air which is 

 clofed up in the afpiration pipe, from the furface of 

 the water a to the pifton, having then more fpace to 

 occupy, becomes more rarified than the external air. 

 This laft then preffes more forcibly upon the furface 

 of the water a, and caufcs it to rife in the afpiration 

 pipe, till the interior air has regained its former den- 

 fity by occupying lefs fpace. Thus, after feveral 

 ftrokes of the pifton, the water reaches the body of 

 the pump, and paries over the pifton, by railing up the 

 fuckers s and S, one after another, and the pifton, by 

 its fubfequent elevation, forces the water to efcape at 

 the fpout E. 



As it is the prefiurc of the air which caufes the 



water to rife in this pump, and as this prcffure can 



fuftain only a column of water of about thirty-two 



feet, it is clear that the afpiration or fucking pipe 



G g a Should 



