Tide

Term given to the alternate rising and falling of the water of the oceans, seas, bays, rivers etc. twice in every 24 hours 29 minutes; caused by the attractive forces of the sun and moon, the moon’s influence on the water of the earth being 2 ’/2 times that of the sun. In several seas, the Mediterranean, Baltic etc. for instance, the rise and fall of the tide is very slight, although in other parts, as the Bristol Channel, it sometimes reaches a height of 36, and at Gloucester even 72 feet.