#567: Urgent Mission explain

[Cueball is coming out of star shaped hole, the hole has black stripes in it. Cueball has one leg inside but the rest of his body outside the hole. He points one arm at Benjamin Franklin. Franklin is sitting in a chair at his desk writing with a quill on a piece of paper. He is drawn with square glasses and long hair, but only at the back of his head, leaving most of his head bald.]

Cueball: Benjamin Franklin?

Franklin: Yes?

Cueball: I bring a message from the future! I don’t have much time.

Franklin: What is it?

Cueball: The convention you’re setting for electric charge is backward. The one left on glass by silk should be the negative charge.

[Caption below the panel:]

We were going to use the time machine to prevent the robot apocalypse, but the guy who built it was an electrical engineer.