﻿1050 



Prof. Townsend and Mr. Bailey on the 



24 millimetres pressure, / for pure hydrogen at one millimetre 

 pressure, and l a for pure argon at one millimetre pressure. 

 The free path l a is obtained from l m and l h by means of the 

 formula : 



_1_ = 24 1 



(5) 



The free paths h and Z>„ are shown by the curves in fig. 7 



Fig-. 7. 



3 

 1 



\ 



\ 











/ 







\ 









/> 



/ 







\ 



V 





9'" 



^ 











\ 



* 



f 



r 









\ 



\ 

















*k 



















^N 



%± 



itfie. 





















**•**« .Ji 



to 



IZ 



/* l(> 



M, */0" 



14. The free paths in pure argon at a millimetre pressure 

 are shown by the curves [a) and (b) (fig. 8). Curve (a) for 

 the lower velocities of agitation u, gives the free paths 

 obtained from the measurements of velocities of electrons in 

 a mixture of hydrogen and argon, and curve (b) the free 

 paths obtained from the velocities in pure argon. The 

 free paths for the range of velocities from ll'5xl0 7 to 

 13-5 x 10 7 were found by both methods, and the curves tend 

 to coincide with the larger velocities. Exact concordance 

 can be expected only at points where the variation in the 

 i'ree path with the velocity is small, or where the velocities 

 of agitation are very near the mean velocity u. For 

 velocities between 4 X 10 7 and 14xl0 7 there is a large 

 increase in the free path as u diminishes; and as explained 

 in section 11, the free path calculated by formula ^4) from 



