The ´Quoddy question — Time and tide

For the third time in thirty years, a major effort is being made toward the realization of the sixth wonder of the modern world, the Passamaquoddy Tidal Power Project Since the dawn of recorded history, man has been intrigued and puzzled by the phenomenon of the ocean tides that are caused by the gravitational pull of the moon and sun. About every four weeks — at the time of the new moon — the sun and moon lie in the same direction from the earth; and, fourteen days later, at the time of the full moon, these bodies lie in opposite directions. When either condition occurs, once every two weeks, the lunar and solar gravitation forces supplement each other to produce maximum, or “spring” tides. When the moon is at its quarter phases, however, the sun and moon subtend a right angle to the earth, as shown in Fig. 1. Their gravitational pulls oppose and partially neutralize each other, and produce minimal tidal ranges — or “neap” tides — that are only one third as high as spring tides. And when the moon is either new or full, and simultaneously in perigee, the tidal range is unusually great.