winter ice, which severely disrupts shipping in colder climes, may no longer pose a problem. A Canadian marine engineer, Per Andersen, claims that he has found a technique to control ice formation. His wave generator projector could prevent sea water from freezing, by producing artificial waves ( New Scientist , Vol 151, No 2043).

When sea water is mechanically agitated, the deeper, warmer water gets mixed with the colder surface water. Andersen has tested his prototype in Canada. The machine is 7.5 m long. It consists of a floating helical roller