316 



Mr Willows, On the distance between the striae &c. 



electrodes caused by successive discharges, and so the further 

 measurements were taken while the discharge was passing. The 



TO PUMP 



Fig. 5. 



difference of potential of the terminals was taken by an electro- 

 static voltameter. 



On decreasing the distance between them, the difference of 

 potential fell to a minimum and then rose rapidly, but the critical 

 distance was always considerably less than the distance between 

 the striae ; in fact, the minimum did not occur until the anode 

 had entered the dark space. 



In conclusion I must thank Prof. Thomson for much help and 

 encouragement. 



Cavendish Laboratory. 



The teaching of Mechanics by experiment. By Prof. Ewing. 



[Bead 5 March 1900.] 



Prof. Ewing pointed out how by a course of suitable experi- 

 ments students could not only be rendered familiar with the 

 general principles of Mechanics but could at the same time learn 



