imitates the Behaviour of Dielectrics. 229 



2. A simple twisted wire is not, however, able to imitate all 

 dielectric effects. Hence an endeavour has been made to 

 follow up this analogy more completely, and has resulted in 

 the construction o£ a model from which, by the application 



Front Elevation of Model, with Cylinder in section. 



of weights, curves of variation of velocity with time can 

 be obtained strikingly similar to the curves of current- 

 variation with time given by condensers when charged and 

 discharged. A simple form of the model can be made by 

 taking two short lengths of spiral spring S p S 2 , and a metal 



