﻿552 Dr. H. W. Malcolm on Double Refraction in 



further the water has penetrated into the tube, the more it is 

 dammed and the slower grows the motion ; this may be 

 caused by particles dragged along by the water blocking up 

 the holes. Or the water may pass through holes in a series 

 of transverse lamella? ; by hydrostatic pressure these lamella? 

 are pressed together and shut like a kind of valve. If the 

 velocity is proportional to the voltage divided by the distance 

 travelled, or ds/dt = Au/s, then s 2 — Aut + & constant, which is 



Fig. 2. 

 '30 



to be put 0. In Table II. are given the values of s 2 /T ; these 

 increase till about one-fifth of the tube has been traversed ; 

 this increase is partly to be explained by the fact that the 

 curves in fig. 2 do not begin from the origin. The values of 

 s 2 /T multiplied by the square of the radius and divided by the 

 voltage are approximately equal. 



