378 ELECTRICITY. 



pass irom the inside to the outside of the glass jar. 

 When the shocks are to be given with this appa- 

 ratus to any particular part of the body, for 

 instance, to the arm, then instead of the chain x, 

 which must now be taken away, two slender and 

 pliable wires, E L, I L, are to be fastened, one to 

 the open ring E of the electrometer, and to the 

 brass hook I of the stand H I, which communicates 

 with the outside coating of the jar. If the jar has 

 not the stand H I, the extremity I of the wire I L 

 may be simply rested under, or may be tied round 

 it. In short, it must be put in contact with the 

 outside coating of the jar, in any convenient manner. 

 The other extremities of the wires must be fastened 

 to the brass wires L, and L of the directors K L, 

 K L. Each of those instruments, justly called di- 

 rectors, consists of a knobbed brass wire L, which, 

 by means of a brass cap> is cemented to the glass 

 handle K. The operator, holding them by the 

 extremity of the glass handle, brings their balls 

 into contact with the extremities of that part of 

 the body of the patient through which he desires 

 to send the shock. The management and conve- 

 nience of this apparatus are easily comprehended 

 by inspecting the figure ; for when the machine is 

 in motion, and the apparatus, &c. is situated as in 

 the figure, the discharge of the jar must be evi- 

 dently made through that part of the patient's arm 

 which lies between the knobs of the directors; 

 and the operator, whilst an assistant keeps the 

 machine in motion, lias nothing more to do but to 

 hold the knobs of the directors to the extremities 

 of the arm, or to any other part of the body that 

 is required to be thus electrified; always taking 

 care that the two wires E L, I L, do not touch 

 each other, because, in that case, the shock will 



