FAEMEES' INSTITUTES. 



3G5 



me to be irreconcilable with the statement that " the repulsive energy of the 

 electrical discharge at right angles to the axis remains of the same intensity as 

 in the case of a statical charge," because in the statical condition no electricity 

 can be drawn from the interior of a charged prime conductor. 



The question whether electricity sent through a wide plate will all accumu- 

 late at the edges and no part pass along the center of the plate, "was submitted 

 to experimental test as follows : parallel strips of tin-foil were pasted on a wide 

 plate of glass, the cuds being connected by cross strips of tin-foil ; the parallel 

 strips of foil were then divided into a large number of squares by drawing a 

 sharp knife across them, so that the track of the electrical discharge could be 

 traced by the light at points of interruption in the strips of foil. Cat VI. 

 exhibits the arrangement employed. 







VI 



On passing strong discharges of electricity through this apparatus, the path 

 of the discharge was sometimes by the side strips of foil, but most frequently 

 by some of the interior strips. It seemed to be governed by caprice, — rarely 

 twice in the same path. Trifling variations seemed to determine its path, e. g., 

 the presence of moisture by the breath or a touch of the hand, or the proximity 

 of a body upon which it could act inductively, such as a metallic rod under the 

 glass. I did not find that uniform discharge along the edges which I had 

 anticipated. 



A modification of this experiment for class-room illustration is shown in Cut 

 VII., where parallel strips of tin-foil were pasted on opposite sides of a plate of 



van 



glass six feet long ; projecting strips at a, ~b, c, d, and e were placed at the same 

 distance from corresponding strips from the opposite side ; when electrical dis- 

 charges were sent from + to — the spark usually leaped from c to the opposite 

 strip, frequently from h and d, and rarely from a and e. 



I conclude this subject by saying that, much as I honor the distinguished 

 Secretary of the Smithsonian Institution, on reviewing the whole subject, even in 

 the light of his ingenious experiments, I am led to coincide with the views of 



