Hi I have recently finished reading Jack Dempsey's Championship fighting boxing manual and it's surprising how much of it is still relevant today. I just came across a boxing manual by James Corbit called Scientific boxing. The difference between the 2 manuals is very fascinating. It appears that much of James Corbett manual is more based on bare knuckle boxing where defending the body was more important than the face. In this image they appear to be wearing hot pants. This content is protected Hmmm This content is protected Here is the link it's a free book now. http://www.scribd.com/doc/14747516/Scientific-Boxing-by-James-J-Corbett-1912
I think you have hit the nail on the head when you say that defending the body was a greaer priority in that period. Those 4oz gloves would have made body blows debilitaing.