They included demonstrations on a darkened stage. Special machines called static electric generators like Von Guericke's were cranked up to create large sparks and loud crackling sounds to amaze the audiences. A favourite presentation was to have several people holding hands. One would touch the generator while it was just being cranked up. The person on the other end of the line would touch someone in the audience.
People still enjoy watching electricity shows.
You can see a static electricity generator in action at the Ontario Science Centre in Toronto. There, you will see a demonstration of the Van de Graaff generator. First, a volunteer is chosen from the audience. This person places one hand on the large globe of the generator while it is being cranked up. As the charge builds up on the generator, it also builds up on the person who is connected by a hand.