Early watches which indicate anything more than the time of day are not common, but this example has several notable features. The dial-plate with its engraved border has a conventional chapter-ring for indicating hours only, but within this ring are two further rings for the date and the 'age' of the moon, read against the tail of the hand. A revolving central disc has an aperture through which may be seen the phase of the moon, and engraved on the disc is an aspectarium giving information concerning the planetary relationships.The pre-balance-spring fusee movement has turned baluster pillars and a main spring-barrel with ratchet set-up. It has a verge escapement with a pierced and engraved balance cock pinned to a stud on the back plate.The oval case is made of gilded-brass with an applied silver band engraved with scrolling foliage. The cover has a latched and removable horizontal sundial with a central compass for orientation. The movement is signed 'Coenrad Jacobs Leouardiae'.