THE SEAS SECRETS

Timaru Herald, Volume CXXXVII, Issue 19451, 28 March 1933, Page 10

THE SEAS SECRETS

REVEALED ON LAND. Secrets of the sea which made an eager juvenile audience cheer with delight or stare in surprise were revealed by Professor A. O. Rankine, at the second of his lectures for children at the Royal Institution, London. The sea was actually in the building—in tanks and jars. Professor Rankine believes in realistic demonstration. He wanted to show why it is difficult to drown in the Dead Sea if you keep your mouth closed. So he had a miniature of the real thing, with the water the exact density of that in the Dead Sea. Into this heplunged a doll of the same degree of solidity as a live baby. Of course the doll floated—and the children cheered. But there were no cheers—only questioning looks—when the doll, placed into ordinary sea water, sank out of sight. During the next demonstration there must have been times when the small audience imagined they were at sea in the far Caribbean. Professor Rankine had the lecture hall in darkness while he showed how the tydrophone, the latest Admiralty device for measuring the depth of the sea by sound, is operated. Somewhere in the stern of the ship, sound waves are sent to the bottom by a blow on a metal plate, which gives out 2000 vibrations per second. Forward is the hydrophone, which receives the echo from the ocean bed. According to the time taken for the echo to be received, the depth is registered. The progress of the “sound sounding” was flashed on a diagram, and the audience, in addition to hearing the tapping on the plate, heard the swish of the water against the sides of the good ship Royal Institution in their ears. Using two long, shallow basins, Professor Rankine disclosed to the children almost all there is to be known about waves. There are no “mountainous” waves, he said, for the biggest ever recorded were 560 ft high. He manufactured waves of all sizes on his miniature seas, and a clockwork boat plunged forward with the seas or battled against them, amid the cheers of the anxious watchers on the plush-backed shores. Two of the children were determined to hear all that was said. They used ear trumpets.