While searching on the internet I came across an old post on ancestry.com. At the bottom of page 2 of that thread, someone recently attached a 2 page letter from Lodge about the origins of the Blacklock and Lodge foundries. Not sure I have a right to attach the letter here, so I'm just providing the link to ancestry.com:
http://boards.ancestry.com/thread.aspx?o=10&m=84.3.1&p=surnames.blacklock
http://boards.ancestry.com/thread.aspx?o=10&m=84.3.1&p=surnames.blacklock