( 4 ^ ) 
sg.^__r will be to the Velocity the fame Column 
would have from the PrelTure occafioned by the 
centrifugal Force, 
as 
^ — , f v <v ) 
V i ,1 or i to V — I- 
R — rxV 
Laftly, Since the Velocity proceeding from the 
Aftion of Gravity upon a Column = R — r, is al- 
ways a known Quantity ; it may be call’d = a (e- 
■-qual in this Cafe to if. 38 Ft. per Second) andconle- 
cjuently the PrelTure proceeding from the centrifugal 
Force will be a x — 1 or, av x y/ - — 
R — rxil R — rxS 
or ; — . er:. : That is , in this Machine 
VR-rxS 
15. 38 x 16. 71 _ „ „ . . . 
• — - — - = 49. 67 Ft. per Second. And if we 
V 4. if X 16. I 
add to this the Velocity of the outer Circle in the 
Tangent of which the Air efcapes, which (in the 
Suppofition we made of two Revolutions in a Se- 
cond) is 44 Feet per Second, we fhall have =93.67 
Feet per Second. 
N. B. This Calculation fuppofes the Bore of the 
Sucking-Pipe fufficiently great to furniih as much 
Air as would elcape, according to this Velocity ; 
but in this Machine the Sucking- Pipe being no 
greater than the Ajutage or Blowing-Pipe, the Ve- 
locity proceeding from the PreiTure occafioned by 
the centrifugal Force, and from the Velocity in the 
the Tangent (which may be reprefented by a Column 
of Air of fufficient Height to give the Velocity of 
93.67 Ft. which is 145.881 Ft.) muft be divided 
