The humour of these nicknames is not striking. Jack the Bald(calvus) is Calvin; Jack with a lantern represents the enthusiast with his inward light. Cf. Hudibras, Part 1, Cant. i. l. 505
"'Tis a dark lantern of spirit,
Which none see by but those who bear it."
— Note Section 6, p. 152, 1. 27