( 6i9 ) 



On Certain Properties of a Field of Force Due to 

 a Single Mass. 



Bj Francis E. Nipher. 



Let )n (Fig. i) represent the acting mass. 'At any distance r' 

 along any radius, the force will he mr'~-. At the point O 

 draw any line at right angles to the radius 7nr\ and let r repre- 

 sent the distance from 7)i to any point on the line. The line 

 drawn at right angles to the radial line will be tangent to a cir- 

 cle whose centre is m and whose radius is /-'. For brevity we 

 shall call this line OT the tangent line. 



