The mariner's compass, which enabled mariners to know the direction in which they were sailing, has always been one of the most important navigational instruments.

This example is mounted in a wooden box to keep it safe (the lid is now missing). The compass itself is mounted on brass gimbals to keep it steady on a moving ship. It has a single iron needle with a brass cap that rests on a spike projecting from the bottom of the bowl, which also contains some lead to weigh it down and keep it steady. The compass card is made of paper and is marked both in degrees and with the points of the compass. North is indicated by a fleur-de-lys, while the other cardinal and half-cardinal points have images of figures representing the sun, moon, Mercury, Mars, Venus, Jupiter and Saturn. Some small blobs of sealing wax remain on the underside of the card (they were originally put there to keep it balanced).