a new-confirucfed Air- Pump. 519 
. Fig: 4. is a fide view of the pump, fhowing the fituation of 
_ the valve-pump and handle of the cock ; where A is the pump, 
. and B the handle. .. 
, Fig... is the Ma Rd which fcrews the key of the cock 
into its fhell, and keeps it tight: the upper furface of it is 
marked with directions to turn the key fo as to produce the 
effect defired : for when the mark on the key agrees with the 
mark on the plate, the pump exhaufts, and fo of the reft- 
