Photo taken sometime between 1900-1910. As you can see the patient has some electrical wires connected to his fingers and wrist. Also there's a restraining chain crossing the "subject's" chest for some reason. That probably was a pay-as-you-go thing back then. A really big metal pot was placed in front of "the patient" for whatever purpose(s) you can imagine...no comment here.

Anyway, when the dentist "threw the switch" you can betcha the patient did not feel a bit of a thing as the dentist administered his "procedure".....