We are standing in the Captain's Day Cabin looking into the Captain's Sleeping Cabin.
"To be fitted with Water-closet, Bath &c., as is usual in H.M. Service, or such conveniences in lieu thereof as may be directed."
Specification, Admiralty 1 July 1867
The photo is from the Peruvian Turret Ship "Huascar".
There was a skylight over the Captain's Day Cabin.