508 



Mr. C. G. Darwin on the Collisions of 



connected with the fact that if 7 = 0, H has initially exactly 

 such a motion that it would come to rest midway between 

 the halves of a. For 06, 0'7 there is a single oscillation, 

 but in the higher values 6 never becomes negative. After 

 obtaining the p, 6 carves we convert them into p, #, a process 

 only affecting those for which &<0-7. Fig. 9 shows the 

 curves. The discontinuities in - 5, 0*6, 0*7 are of the type 



Fig:. 9. 



Collision Relation for Bipole. 



The distance between the poles is 2 units. The numbers on the {p, 6) 

 curves refer to the value of k, which is proportional to 1/V 2 . The 

 inset gives the (p, V) curves in the same form as fig. 5. 



with one tangent vertical. Towards 90° all the curves rise 

 very steeply, but it has been necessary to omit these angles 

 in order that the important part, from 0° to 50°, might be 

 drawn on a reasonable scale for comparison with fig. 4. 

 From the p, curves with constant k, we deduce the p, V 

 with constant 6. These are shown in the inset of fig. 9, 

 plotted with k (that is, 1/V 2 ) as abscissa. This completes 

 the description of the collision relation. 



10. The Square Nucleus. 

 The collision relation of § 9 was calculated on the very 

 arbitrary assumption that we can represent the action of 

 a plate by means of a pair of poles, twisted round so that 



