Injuries produced by contact with electric circuits

This paper discusses the results of a series of experimental investigations that have been conducted at The Johns Hopkins University on the effects of electric shock. Rats and dogs were used as the experimental animals. They were completely anesthetized before the experiments. Studies of the effects produced by electric current upon the nervous system and upon the heart are reported. Three types of circuits were used in the work, namely, direct current, alternating current, and the discharge of an impulse generator.In the first series of experiments, the effect of voltage was studied and it was found that low voltage alternating current circuits are much more deadly than direct current circuits of the same voltage. At voltages of 1,000 and higher the reverse is the case. In this work, the importance of the size of the animal as related to the injury was definitely established, larger animals being able to withstand a greater current than those small in size.The resistance offered by a body in an electrical circuit was determined. The resistance is made up of two parts—the contact resistance, and the ohmic resistance of the body proper. The resistances offered at the contacts are of the nature of a voltage drop and are largely independent of the current flowing. The importance of contact resistances in industrial accidents is emphasized.In a second series of experiments the effect of the current path through the