900. Mr. A. L. McAulay on the Recoil of 



which give the following values for the constants : — 



RaC. ThC. 



A=-21xl0" 8 C= 6-25X10" 10 A=r3xl0-< 0= -4X10" 11 



33 = 2-16X10" 8 D=-l-19xl0- 11 | B=5-56xl0~ 8 D=--92xl0~ u 



From these constants and the equation 



N = F(0) = A6>+JB6> 2 + C<9 3 + D<9 4 

 the curves of fig. 3 have heen plotted. 



6. The Field near an a Particle. 



Fig. 4 is a diagram of the field near an a particle deduced 

 from the figures given in section 4 on the assumption that 

 the forces are purely electrostatic. The simple form taken 

 for the field is purely arbitrary, but the results represented 

 graphically by the diagram are quite independent of this. 



Fi* 4. 





5.80 



The dotted lines represent surfaces, close to the a. particle, 

 whose potentials (in millions of volts) are given by the 

 numbers marked on them. The a particle is moving in 

 the direction of the large arrow, and the short heavy lines 



