L-4
The attractive young woman is unknown but she has taken the time to note on the back of the photo that it was taken aboard the L-4 and the vessel had spent four days “...in the dock here...” that has implications of dry docking. It is possible the photo was taken in England as the L-4 and other US submarines went to Portland, England and were dry docked before making the return trip to the US. She arrived at Philadelphia, Penn. on February 1, 1919.
The young woman has placed her left hand on the top of the 3”/23 caliber deck gun of the submarine. The curved disk is the gun's splinter shield and the gun as a whole, when not in use, would rotate to a vertical position and retract into the superstructure into the gun's water-tight housing. The curved splinter shield would mate with the housing's top edge making the breech water-tight.
