A few days ago, Lindell and I were discussing something different when this watch ‘wormed’ its way into our conversation (my apologies for the photography). Sight unseen, using the serial number only (4737116), Lindell read to me the information regarding the watch from Meggers’ book. According to Meggers, this is a model 3, grade 405 made in 1926. Our conversation drifted to double rollers and screw held jewel settings (both of which this watch has) and if they were used by Illinois as standard practice by 1926. Consequently, I thought no more about the model and grade numbers – until later that evening. Then it occurred to me that the model 3 with which I was familiar is a three-quarter plate mechanism and this watch contains a bridge mechanism. In fact, it resembles the plate layout of a model 5, but is a going barrel rather than a motor barrel. So now I am stumped. Can someone identify this mechanism?

Mark.
From what I can see in my references all regular 12 size model 3s have the bridge. The model 3 in extra thin size is 3/4 plate.
That would be the regular 12s you have.

Kenny;
Thanks for the information. You supplied the key. The information that I had seen did not indicate that the three-quarter version was an extra thin movement.