What is a binnacle lamp?

binnacle - a nonmagnetic housing for a ship's compass (usually in front of the helm)

Most ships were equipped with a magnetic compass that was kept on deck in a binnacle that could be illuminated at night by means of a lamp burning olive oil.

(I no longer remember where I got these quotes from, or the pictures either, which shows why you should never try cutting and pasting from web sites at 6 in the morning.)