Here is an oversized American pocket? watch made for the Columbian Exposistion in 1896 in Chicago. It was an attempt by a Bristol,Connecticut clock maker named Welch to make a pocket watch. This was their only attempt and only a few were made. Another Connecticut watch company(Waterbury Clock) first watches were oversized also and both used scaled down clock movements as does this one. The case is approx 70mm in diameter and approximately 28mm thick!!

The back has a scene of Columbus landing in America in 1492

Inside the back cover you can see the large winding key and the small loose key to set the time.

Here you can see the very clock like movement with it's large mainspring on the left