PREDICTING THE TIDES

Greymouth Evening Star, 6 December 1928, Page 10

PREDICTING THE TIDES

DONE BY MACHINERY.

Within recent years many kinds of robots (“thinking” machines) have been developed. Familiar among them are the adding and calculating machines now commonly used in banks and business houses. The latest robot is a German invention, and is operated at Hamburg, states a correspondent of the “San Francisco Chronicle.” It predicts the exact time, to the hour and minute, of high tide and low tide for every seaport of Germany, for every day, and it keeps two years ahead on the job with published figures. Thus the mariner, by looking in a printed pamphlet, can find out in a moment at what time the tide will be high or low on any day. The Unied States Government also has a robot that does exactly the same thing, predicting the tides two years ahead for all of American seaports. The machine, sometimes called the “great brass brain,” is housed in the offices of the Coast and Geodetic Survey, in Washington. The German machine, however, is wholly different in construction. The two do not look in. the least alike.

Although their predictions cover a period of only two years, either of these robots could just as easily forecast the tides 1000 yars ahead; or, if properly set, it could tell exactly the time of high tide and low tide at any seaport in the world 1000 years ago. Signs which are also erected in harbours and may be seen from a great distance ■with a telescope or even a field glass, are for the purpose of informing mariners of the stage of the tide. At the bottom of the sign, in the middle, is a wooden rod set vertically. It has two flanges, pivoted to the rod. Turned either way, they form an arrow*. If the arrow points down, the tide is falling; if it points up, the tide is rising.

When the flanges are straight up and down, not forming an arrow, the tide is neither rising nor falling, but is “on the turn.” A pointer to the big figures around the top of the sign indicates the number of feet at which the tide stands above low-water mark. At a tide-watching station is a little house which supports the sign and shelters the tide-observer.