( 44 ) 
II. A Calculation of the Velocity of the Air moved 
by the new- invented Centrifugal Bellows of 
7 Feet in Diameter , and i Foot thicks within , 
which a Man can keep in Motion with Very little 
Labour , at the %ate of two ^Revolutions in one 
Second. Dy J. T. Delaguliers, R ^ 5. 
W HEN the Wheel revolves upon its Axis, 
which is performed in this Machine every 
Revolution in about half a Second, the 
Air maybe confidered as divided into as many con- 
centrical Circumferences as there are Particles of 
Air contained between the leaft and the greateft 
Circle, confequently the centrifugal Forces will be 
as the Radii ; that is in an arithmetical ProgrefEon. 
Ft. 
Let R = Radius of the greateft Circle 3. 5 
r = Radius of the leaft Circle o. 75 
m— Radius of the middle Circle 2. 125 == 
R — r R + r 
r + = 
2 2 
v — Velocity or Space defcribed 
in- a Second in the middle 
Circle, upon the Supposition 
that theWheel revolves two 
Revolutions in a Second. 
S = Space defcribed in a Second? ^ 
by the A&ion of Gravity, £ 
s = 
