Tides are influenced by the orbit of the moon around the earth. To show this, our Tide clock has an extra hand, which makes a complete sweep at the lunar rate of approximately 12.5 hours instead of the normal 12, indicating the state of the tide for a chosen location. The case used is the same solid brass casting, with scuttle clamps, bevelled glass fronts and brass hands, that we use for our Saloon range. Outside diameter 5.5″, face is 3″ and depth 1.75″. IMPORTANT: because the lunar cycle varies with the Earth’s, there are times in a month when actual tides are a few minutes ahead or behind the clock.