Danbury Shakes

[Sam Clements]

Obviously I'm looking for the earliest usage of the term in the US as it refers to hatters and mercury pisoning.  I checked the archive.  Nothing.

A discussion of some length over at Straight Dope some great time ago and a thread over at Dave Wilton's http://pub122.ezboard.com/fwordoriginsorgfrm1.showMessage?topicID=4563.topic  would lead one to believe this is an old term.  Is it?

We'll leave whether "mad" means "angry" or "crazy" for another day.