Two of the bricks that we recovered from a Wisconsin site were impressed
with makers' marks. One of the bricks, a buff/cream-colored variety, carried
an NB-in-diamond stamp, while the other, a brown-colored example, was
stamped with O X W S R.  Has anyone come across these manufacturers' stamps?
 I believe that the widespread use of proprietary marks on bricks didn't
begin until the 1890s, but that's as close that I've able to come to dates
and/or manufacturers of these two bricks.  I'm not sure if their listed in
Gurcke's guide since I don't have access to his book.  Hope someone can
help....  

Thanks,

Kent Taylor