502 



Mr. C. G. Darwin on the Collisions of 



Fig. 6 shows the relations between p and 6 

 of V determined by ^ = 0*1,0 2, 0*3, 0;4, 0"5. 

 no impacts occur at all, and the curve is simply p 

 As p is single-valued in #, it is the same as p. 



for values 



IE n^O-5 



— fjb tan 6. 



The curves 



10 



0-8 



0-3 



! 



0-2 



Fio\ 6. 













J 



/ 0/4 



^3 / 

 / 0-2 



f 



















^ 



' 









/> 



y^ 



i^>"^°y^ 



! 







J^ 



^ 



-^y 





._ 



j 

 i 





A 



%y 









1 

 j 

 i 





10 : 



6 



20 c 



30= 



40 c 



50° 



60°' 



7CT 



80 c 



90 e 



Collision Relation eoh Elastic Sphere of radius b. The numbers 

 on the (J), 6) curves refer to the values of ju/6, that is, are 

 proportional to 1/Y 2 . 



have little resemblance to those of fig. 4. In particular 

 they lie too close together for the small values of 6 and none 

 of them is in the least like curve C. Note that the discon- 

 tinuities of the curves are due to the discontinuity of force 

 and not to the cause described in § 2. 



The elastic sphere would appear to represent, in a general 

 way, systems of any shape, but orientated equally in all 

 directions, and from its failure to give anything resembling 

 the experimental curve, we conclude that the parts of a. must 

 be arranged in some way that can throw H definitely 

 forwards. It may be that a spherical system could be 

 devised to do so, if the operation of the inverse square law 

 at the larger distances were abandoned, but the behaviour 

 when V is small vetoes this possibility. Thus Rutherford's 

 suggestion that his experiments point to a plate-like nucleus 

 receives further support. Observe that there is nothing 

 inherently improbable in this, as the uniform orientation 

 may be connected with the circumstances attending the 

 break-up of the radioactive atom. 



