Nautical compass - Hemisferium
The Cardan or marine compass is a nautical instrument whose use was fundamental in the development of navigation and cartography.
New types of compasses were devised because the rock and pitch of a vessel make ordinary compasses useless. Ship compasses were mounted in a Cardan suspension, which allowed them to remain constantly level.
The compass went through few modifications until the 19th century, when scientists, engineers and navigators improved it notably.