This type of cabin compass was suspended in the beam above the captain's berth and indicated the rudder's steering errors and possible changes of course. This allowed the captain to check his vessel's direction without having to climb onto the bridge.

The Smithsonian holds engravings by a François Morel (France 1768 - Italy 1832), a pupil of Giovanni Volpato who specialised in city and architectural views. He is most famed for his copies of now-lost Pompeian wall paintings, which are kept at the Archaeological Museum in Naples.