UNITS IN THE ELECTROMAGNETIC UNIT OF ELECTRICITY. 
717 
“ Fig. 4. 
“ Section on line s, t, w. 
“a, c are stiff insulated horizontal contact bars connected to the two jDoles of the 
battery, d, e,f are insulated springs normally touching a and c on the under side. 
d is connected by a wire to the guard ring, e to the plate of guard ring condenser, f to 
the sliding condenser, b is an insulated binding screw connected with c for the purpose 
of more conveniently introducing the battery wire. I is a spring connected to earth, k is 
a stiff insulated piece carrying an adjustable point in, normally in contact with the upper 
side of the insulated spring h. From k a wire leads to the quadrant of the electrometer. 
k can at any moment be put to earth by a spring key. The insulated spring g has 
its end between e,f and h, and is normally in contact with neither. The springs d, e,f 
can he simultaneously bent downwards by an insulated plunger. When this plunger is 
struck downwards we have the following operations effected in a fraction of a second— 
1°. Cd and e are in contact with a. 
\ f in contact with c. 
2°. d, e, and f insulated. 
3°. f d connected to l. 
L e,f and g connected together. 
4°. e,f g, h, k connected together. 
5°. Connexion of k and li broken. 
“The whole switch, binding screws and all, is covered with a brass cover connected 
to earth and provided with apertures for the connecting wires. The ebonite legs 
which carry the pieces a, b, c, d, e, f, g, k are attached to a brass base plate, so 
that if any leakage occur from a, b, c, d, e, or f, it shall be to earth and not to the 
electrometer.” 
4 z 
MDCCCLXXXIII. 
