94 Mr. J. J. Waierston on some Electrical 



The characteristic of the magic pane is, having' the engaged- 

 lines of force enclosed and compressed laterally by the disen- 

 gaged or free lines, which may issue either from one side or 

 both. Fig. 14 represents them as issuing from one side; but 

 as the free lines, by various causes, are gradually discharged at r 

 surface^ the lateral enclosing force of compression diminishes, 

 and the engaged lines expand outwards until on the outer side" 

 of x appears the male force in a free or inductively active state : 

 these free lines extend from outside x to outside r, and enclose 

 the engaged lines that extend from inside x to inside r (fig. 15). 



Fig. 16. The wax plate in the condition represented in fig. 14 

 is now shown separate from the excited sulphur cake. The 

 engaged lines become free, and are directed with male aspect 

 from both sides of surface x, and the wax plate seems positively 

 excited on every side. 



Fig. 17. The coating on w side has been touched and the lines 

 between w and x are engaged, the charge on w being negative 

 but directed inwards, and masked and enclosed by the free lines 

 issuing from the positive roots on the outer side of surface x. 



Fig. 18. The coating on x has now been touched, by which, 

 not only the free positive escapes, but also a certain portion that 

 was engaged by the negative that is now rendered free on the 

 outer side of w. 



The behaviour of non-conducting matter under conditions of 

 excitement and induction, 



35. The behaviour of an excited electric while isolated. — A cake 

 of sulphur 4 inches in diameter and \ an inch thick, after being 

 excited negatively by slapping one surface, a, with a warm silk 

 handkerchief, was placed with this surface resting upon three 

 sticks of sealing-wax set upright (fig. 19). The insulated B. D. 

 was placed on centre of unexcited surface ft, then touched with 

 free wire and removed. The induced charge thus obtained was 

 halved by touching with the twin B. D. Then applying it 

 to the cap of the electroscope, the gold-leaves opened to 90° 

 P., showing the inducing force at ft to be 90°x2N. (first con- 

 tact) . Other observations were taken from a as well as ft, as 

 follows : — . 



h m o h m 



From /Sat 1 24 p.m. 90 x 2 N. From ft at 1 40 p.m. 80 X 2N. 



From ft at 215 p.m. 80 x 1 N. From ft at 3 2 p.m. 30 x 1 N. 



From ft at 11 20 p.m. 85 x 1 P. From ft at 10 20 a.m. 85 x 1 P. 



From a at 11 20 p.m. 85 x 1 N. From a at 10 20 a.m. 85 x 1 N. 



The gradual transition from negative to positive of the electric 



