The conning-tower and periscope are placed on the upper deck, as shown.
I was glad when I picked up its homely white front in my periscope.
The captain turns the periscope around, scanning the waters.
This periscope was not in use and had not been above the surface.
He looked neither to right nor left but was still at the periscope.
De Hooch went over to the periscope ...