A Boat with Fins.

Swiftly Profiled by thr Action of tr| Wavks~New Motive Fobob. Ton isfcs a«- Naples (his spring hare noticed a JHlle open boat, which set out seaward whenever the sea was rou^h, and particular when the freaoherou* tiiocoo sent the turbulent waves spraying over* the stone coping of the Via Carraciolo. Once having noticed the little frail shell, the fact of iti going out in he ivy weather seemed so muoh more strange since ib was impossible to tell how it moved about. The single person seated in the boat did not row, there was no sail, no smokestack was visible, no wheel, no screw, no boiler, no engine; none of the metal parts unavoidable in motors of any kind, and no noise indicating any of the ordinary motive powers, which man has made a tributary. At the rodder the man was calmly seated directing the little ihell wherever he wanted to go. What was driving the lUtle boat through the turbulent waves? Its inventor and constructor, secretary Linden, of the zoo. logical station at Naples, kindly explained the simple and exceedingly clever invention, which ho has just patented in several countries, and which is to be introduced both in the German and Austrian navies. The forward and aft ends of the boat are provided with vertical steel rods; at the end of these steel rods, which are dipped in the sea, wedge-shaped plates of spring steel of great firmness are fastened honzontioally with the wide and thin end away from the boat. When these pliable plates are made to vibrate by means of the movement of the waves, they set like the fins of a fish, and drive the boat forward. Not the waves alone furuieh the power, for in perfectly still water the mere pitching of the vessel will result in a forward movement. The lowering or raising ot the steel rods with the fine is an easy matter, and the fins tbem> selves can be attached or detached by a simple mechanism in a very few moment!. A trial with the small model of such a boat in one of the basins of the aquarium at the station is highly amusing and surprising at the sams time, '1 he toy is perfectly still when pace 1 in the Water, but as soon as little waves are produced in the basin with the hand or a small board, the toy starts as if driven by witchcraft. The power developed is rather considerable, and it is best compared with the pull exered by a kite in a brisk wind. The new boat, which the inventor has called the Autonaut, is nob exactly a boat without a motor, but one without the ordinary motive powers—as a matter of fact, the steel fin vibrated by the motion of the water is the motor of the Autonaut. Secretary Lindon first conceived the idea of the new motive force while observing the movement of the fishes in thn aquarium, particularly the tail motions, the most important, apparently, in the locomotion of the finny tribe. After many years' experiments, calculations and improvements, his last boat,-'which is thirteen feet long, has recently tun against a strong wind and tide in the Gulf of Naples at the rate of three uiid a half miles an hour. The steel fins were together about ten square fe6t in size, ■i.'id ho has by experiments established the bos! size to be about one-third of the surface upuu which the boat is resting. The fiuß, which were first made ot several layers of thin spring tstee!, are now wroughtoufcofone pieoks, and the most effec ive shape is that of lha dolphin's tail tin. 'The new boat can be ! steered in the ordinary manner, and will i draw another boat heavier thau it is itself. i The apparatus is eh- ap, and can be supplied j to any l;oac even if ib hue other motive I power. No matter liow little wind, the tide movement alono is f.ufficient to impart uuoKgh moti'M) to the waves to propsl the boat., provided with Linden fans. The greatest fieifl of the Lin :cn boat, however, and where its value is inestimable, is in the use of life-saving appara'us which has to travel abort distances in almost always heavy weather. The crew would arrive at the sprit whore they &re wanted iv excellent condition and would be of much more help to a sbipwieckcd crew, than now, when they arrive after dreadful aud often useless efforts '■ against (he overwhelming odds of waves and wind, combined.— Philadelphia Record,