It may be said, too, that the gyrocar is provided with lateral legs that may be let down in case of emergency or when the car is not in use, to avoid waste of energy in needless running of the gyroscope. All in all, it would appear that the dangers of travel in a gyrocar should be fewer than those that attend an ordinary double-track car; and Mr. Brennan believes that it will be possible, with the aid of the new mechanism, to attain a speed of one hundred and fifty, perhaps even two hundred miles an hour with safety. [Illustration: TWO VIEWS OF MR. LOUIS BRENNAN'S MONO-RAIL GYRO-CAR. The gyroscopic mechanism for automatically balancing the car is contained in the cab-like anterior portion. The platform of the car maintains its equilibrium even when the forty passengers are crowded on one side, as shown in the upper picture.] VIII THE GYROSCOPE AND OCEAN TRAVEL It must not be supposed that Mr. Louis Brennan's remarkable monorail car affords the first illustration of an attempt to make practical use of the principles of gyroscopic action. The fact is quite otherwise. The idea of giving steadiness to such instruments as telescopes and compasses on shipboard with the aid of gyroscopes originated half a century ago, and was put into fairly successful operation by Professor Piazzi Smyth (in 1856). More than a century earlier than that (in 1744), an effort was made to aid the navigator, by the use of a spinning-top with a polished upper surface, to give an artificial horizon at sea, that observations might be made when the actual horizon was hidden by clouds or fog. The inventor himself, Serson by name, was sent out by the British Admiralty to test the apparatus, and was lost in the wreck of the ship _Victory_. His top seemed not to have commended itself to his compatriots, but it has been in use more or less ever since, particularly among French navigators. BESSEMER'S COSTLY EXPERIMENT