One of the most remarkable recent developments of the gyroscope is its use as a stabilizer in ships to keep them from rolling in a heavy sea. A comparatively small wheel is mounted in the hold of the vessel with perfect freedom to turn in any direction. If the wheel is clamped so that it cannot precess, the vessel will roll and pitch, but the instant the gyroscope is released it exerts its wonderful powers. The ship rides smoothly and its groaning and creaking ceases, showing that it is no longer subjected to severe strains. Of course, it rises and falls with the waves, but it maintains an even keel as if sailing in smooth water. The object of stabilizing a ship is not merely to cater to the comfort of passengers who are subject to seasickness, but to save wear and tear on the vessel and also to economize time and fuel. An unstabilized ship riding a heavy sea pursues a very sinuous course; in other words, it must travel farther than it would in smooth water. The rudder must constantly be turned to keep the ship on its course, and this acts as a drag on the progress of the ship, slowing it down and wasting the power of the engine. As the ship wallows in the sea it displaces much more water than it does when riding on an even keel and here there is a further loss. It has been estimated that a 15,000-ton vessel running at 18 knots may waste as much as 1,000 to 1,200 horsepower in a heavy sea. If stabilized with a gyroscope, practically all this wasted horsepower would be saved at the expense of a very small amount of power used in keeping the gyroscope spinning. The first man to stabilize a ship with a gyroscope was Dr. Schlick, who demonstrated the powers of this mysterious mechanism in 1906. His stabilizer, however, was not sensitive enough to provide perfect stabilizing. The ship had to roll some before the gyroscope exerted its corrective forces. Recently, however, Mr. Elmer A. Sperry has improved the stabilizer, making it so sensitive that there is practically no rolling or pitching of the vessel. Curiously enough, the gyroscope may be used not only to keep a ship from rolling, but also to make it roll. Should a vessel run upon a mud flat it may be rocked by braking or accelerating the precessional motion of the gyroscope. In this way the ship may work itself out of the mud bank. Ice breakers are equipped with gyroscopes, so that they may be rolled to prevent them from being frozen into an ice pack and to assist them in crushing their way through the ice. THE MONO-RAIL CAR