This lens is part of the periscope that allowed U-Boats to see what was happening on or above the water.

After sinking more than 20 ships during the last year of the war, U-117 surrendered at Harwich, England after the November 1918 armistice. A.R.M. Lower, a Canadian officer in the Royal Navy and later a prominent Canadian historian, once owned the lens.

Periscope Lens
CWM 19740259-010