Scattering of a, Particles by Gases. 295 



the centre outwards along four radii 90° apart. The averages 

 of the four equal areas at the same distances from the centre 

 were taken. 



Some typical results are shown in fig. 3 for the case of air, 



Fig. 3. 



400 



300 



200 



100 *- -> 100 



Distances from Centre in fl . 



200 



300 



400 x; 



the left-hand part of the curve as shown being simply a replica 

 of the right-hand part. The general distribution oE the 

 particles for different air-pressures can be seen from the 

 figure, but the results are not sufficiently accurate to deduce 

 the most probable angle of scattering with any certainty. 



The primary intention of the investigation was to determine 

 the scattering in hydrogen, which is even smaller than in air. 

 This problem has not yet been solved, but in view of the 

 necessity of discontinuing the experiments, it was thought of 

 interest to indicate a method which shows good promise of 

 success. 



In conclusion, the writer desires to express his indebtedness 

 to Drs. W. Makower and N. Bohr for their kind help and 

 guidance in carrying out the research. He is also thankful 

 to Sir Ernest Rutherford for allowing him to carry out the 

 above experiment in the Physical Laboratory of the Uni- 

 versity of Manchester* as well as for his kind interest and 

 advice. 



