this section is mainly focus on the develpoment of bb movement from the 30's. there are 3 series of movement being 1)8 3/4 with watchmaker intruction 2) autor rotor 3) perpetual.
examples in the picture is a full watchmarker instruction 8 3/4" prototype movement
1st series bubbleback, double name beyer
this is really hard to come by, a criss cross double dial on a 8 3/4 first series makers instruction movement, 3 pieces case, oversize crown, the great grand father of all automatic rolexes...