The new Douglas DC-2 transport plane combined all the knowledge of thirty years of flight. In the early “thirties” air transport began to come into its own. Plane-to-ground radio was put into use. The radio range, or radio beam, pioneered by “Shorty” Schroeder with Henry Ford in 1927, was guiding our airliners on their course. The radio beam flashed the Morse code letters “A” and “N” along the flight path of the airliner. The dot-dash of the “A” signal was flashed on one side of the route and the dash-dot of the “N” signal was on the other. In the center of the flight path the two signals blended into a steady hum. This hum notified the pilot that he was “on course.” Regardless of fog, rain, or darkness the pilot got his course through his earphones. The application of the gyroscope to aircraft instruments was a great step in the advancement of flying. First experimented with by Lawrence Sperry in the early days of the airplane, the constant action of the gyroscope was used to register the changes of attitude of aircraft in flight. It was first used in the Turn and Bank Indicator, then in the _Gyro-Horizon_ and _Directional Gyro_. Power-driven gyros constantly whirled in the direction in which they were set. They were attached to dials on the instrument panel and to the plane itself. The position or attitude of the gyro was indicated on the dial in relation to the attitude of the airplane. As the plane changed, the constantly spinning gyro remained in its correct attitude. The gyro position and the position of the plane shown on the dial told the pilot the actual attitude of the plane in the air so that he could correct in relation to the true position indicated by the gyro. This allowed the pilot to keep his plane on a true compass course and in the proper flight attitude without having to see the horizon. Thus a pilot could fly through fog or total darkness with both ease and safety. [Illustration: WHEN THE GYROSCOPE IS SET SPINNING WITH ITS AXIS POINTED TO THE CENTER OF THE EARTH IT WILL RESIST ANY FORCE THAT ATTEMPTS TO CHANGE ITS POSITION.] [Illustration: THE GYROSCOPE AUTOMATIC PILOT CONTROL CABLES THE GYRO UNIT CONTROLS MOTORS THAT OPERATE THE CONTROLS OF THE PLANE. THE GYRO PILOT AUTOMATICALLY FLIES A PLANE IN ANY POSITION THAT THE PILOT DESIRES. WHEN THE GYRO IS SET TO FLY A PLANE IN A LEVEL POSITION, IT WILL RESIST ALL ATTEMPTS TO CHANGE ITS POSITION. IF THE SHIP SHOULD NOSE DOWN, THE GYRO STARTS THE CONTROLS TO WORK, TO BRING THE NOSE UP. THIS IS TRUE IN ALL FLIGHT MOVEMENTS.] The gyro instruments soon proved their value and were installed in the cockpits of transport planes the world over. The Sperry Gyropilot then was perfected. This remarkable instrument, based on the gyroscope movement, was developed actually to manipulate automatically the controls of even the largest airplane, keeping it directly on the desired course and leaving the human pilots free for their many other duties.