196 
ON THE MOTION OF ELONGATED PROJECTILES. 
6. The way in which drift arises may be seen by considering the 
Lagrangian equation (i) remembering that N is now zero. If u x repre- 
sents the velocity of the centre of gravity in the direction 6 + this 
A 
equation reduces to 
AS - A ip sin S cos 6 + Cn sin 6 = - (P - R) u x w. 
From this initially, since 6, u x then vanish 
A6= ~{P-R) u x w 
where 
_ Mg cos£ 
sin/3-zcos/3= ° p . 
Thus the fact that the tangent to the path of the projectile gradu¬ 
ally drops below its initial direction leads not (as has been stated) 
directly to a diminution in the value of but to a diminution in 6, and 
when the. axis rises the condition of constant angular momentum about 
a vertical through the point of projection makes the shot point to the 
right. 
The subsequent angular motion is that of a rigid body of principal 
moments A, A, G under the action of a field whose force-function is 
(P - R) w\ 
