Doxa Chronograph vintage 1930's

Case Diameter: 35 mm
Case Height: 12 mm
Case length: 42 mm
Lug Width: 18.5mm
Movement: Doxa signed Venus 140, 17j manual wind
chronograph, 18,000 bph. Time is read at the 12 sub-dial,
the sub-dial at 6 is a 30-minute elapsed time.
The center second hand is for the chrono function.
Case material: Unknown