[ 417 ] 
General Proposition. 
Suppofmg an homogeneous fphere OABCD (Fig. i.) 
revolving unifortnly about its centre , to be added on at 
the extremity A of the radius OA, in a direction AL 
perpendicular to the plane of the equator ABCD, and 
parallel to the axis of rotation Pp, by a given force , 
tending to ge?ierate a new motion of rotation at right 
angles to the former j It is propoj'ed to determine the 
change , that will arife in the direction of the rotation 
in confe queue e of the Jdid force. 
Fig. i. 
Let F denote the given force, whereby the motion 
about the axis Pp is difturbed, fuppofing/' to repre- 
fent the centrifugal force of a fmall particle of matter 
in the circumference of the equator, arifing from the 
fphere’s rotation 3 and let the whole number of fuch 
particles, or the content of the fphere, be denoted 
by c : let alfo the momentum of rotation of the 
whole fphere, or of all the particles, be fuppofed, 
in proportion to the momentum of an equal number 
V o l. 50. H h h of 
