Gimballed compasses are primarily used used for nautical applications, where the compass needs to be kept level whilst the ship is moving around. The is done by use of a two pairs of bearings at 90 degrees to one another and a gimbal ring. By ensuring the compass base is heavy enough the compass remains level and easier to read.
When the compass becomes larger it is often fitted in a binnacle and installed as a permanent fixture. It can also be fitted with the means to “adjust” the compass.
Adjusting the compass is done to compensate for metal fixings and structures that are used in the construction of modern ships.