242 UNIVERSITY OF VIRGINIA PUBLICATIONS 



ds being the element of arc length described by any point distant r from M. 

 The velocities are proportional to the distances of the points from M and 

 their directions make equal angles with their radii vectores from M. The 

 path curve described by any point homogeneously connected to ABC is 

 similar to that of any other point and is known when the path curves of 

 A, B, C corresponding to given mutual attractions are known. Sut-h a 

 movement of the points of a plane is a homogeneous similitudinous attrac- 

 tive movement. 



