the Rotatory Motion of Bodies. . 277. 
// /// 
with the momentary pole p, />, 8cc. changes its place. 
/ 
Confequently, if pr be an arc in the faid immoveable 
concave fphere whofe line is 
rv 
y/u l + v z f 
, the great* 
I+ r z f 1 
/ i a it Hi v// 
circles q p, q p, q p, Sec., will interfedt each other at the 
point r. 
7. Moreover, the force f being invariable and adting 
as exprefled in the preceding article; the primitive pole 
/ Ht 
p and the momentary poles p, p y . Sec. will all be founds 
t nit* 
in a circle ppp 8cc. defcribed upon the furface of the 
revolving fphere, as obferved in that article; which, 
circle, during the adtion of the force of f, will (as is alfo 
obferved in the faid article) always touch and roll, along 
/ 1/ Hi 
the immoveable circle (p p p &c.) whofe radius we 
have juft now found — 
rv 
, the point of: 
\/ u z + v z y 1 e 2 u 
1 +“ 
contadt being always the momentary pole. . 
t. !< 
Let the line of the arc PQ_of the great circle RpQji t 
in the revolving fphere be equal to h, the radius of the 
i a ni 
faid circle ppp 8cc. then will the point Q_and its oppo- 
fite point’ (o) in the furface of the faid fphere, during 
the adtion of the force F, deferibe circles in the fur- 
3, rounding 
