46 APPLICATION OF 



Shocks. The last method of applying common electricity as 

 a remedial agent, is by means of shocks. The method is simply 

 to discharge a Leydenjar through the affected part or member, 

 as may be considered advisable. The easiest method of accom- 

 plishing this is, to twist a thin wire round the exterior coating of 

 the jar, and having charged it, to bring the wire in contact with 

 one end of the course it is intended to traverse, and the brass 

 knob of the jar to the other end. Against this method, however, 

 the objection lies, that we are not enabled to measure the 

 amount of the charge ; to attain this object, it is necessary to 

 interpose a discharging electrometer in the circuit. The knob 

 of the jar being now placed in contact with the conductor of a 

 machine in motion, and at the selected distance from one of the 

 balls of the electrometer, the discharge takes place so soon as 

 the free electricities have acquired sufficient tension to force 

 their passage through this interval, and a shock is felt in the 

 part of the body which completes the circuit. If this be too 

 strong, the ball of the electrometer must be placed at a less 

 distance, and vice versa. The two parts of the body between 

 which it is intended that the electricity shall pass, are to be 

 touched by the balls of two separate directors, held by an 

 assistant, and connected by means of chains, the one with the 

 electrometer, and the other with the outer surface of the jar. 

 Thus, if one of the directors be in contact with the hip, and the 

 other with the knee, when the discharge takes place, the shock 

 will be felt along the entire thigh. The above described method 

 of regulating the shock, should be familiar to such as employ 

 electricity in the practice of medicine. The discharge of a 

 small jar proves fatal to the smaller animals ; and there can be 

 no doubt that by means of a battery of no very great surface, 

 human life might be destroyed. The power too, of sustaining 

 the shock, is very different in different individuals, and even 

 varies in the same person, so as to differ at different times and in 

 different states of the system. These circumstances enjoin 

 caution in the administration of electricity, particularly by means 

 of the jar ; and it may be added that its injudicious and indis- 

 criminate use has proved extremely injurious. 



