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Show Maps Eliminated With New Air Compass AVIATORS at last have devised a compass which not only is perfectly adapted to air work, but In addition is so advanced in Its operation that charts and maps are unnecessary even on long flights. Two army flyers recently sealed up their maps in a tin can, tossed them into their plane at Dayton, Ohio, and started the 575-mile trip to Mitchel field without a thought as to whether there was land, water or cloud beneath be-neath them. And they landed at Mitchel field as surely and directly as if they had traveled on rails. The wax seals on the map container were unbroken. un-broken. The earth inductor compass, as It is called, Is the product of the government gov-ernment experimental station at Mc-Cook Mc-Cook field. One of its originators. Bradley Jones, made the first map-less map-less flight with Lieut. II. O. Downey. On landing he explained the instru- lH'Ilt. "Adaptation of the mariner's compass com-pass to the airplane has never been a complete success." Mr. Jones said. The steel In the motor would give it an error of as much as twenty degrees. de-grees. The needle sometimes spins around futilely. We needed something some-thing more dependable and we've got it. The earth inductor compass is pUeed In the tail, away from the mo tor's influence. It is actuated by the earth's magnetic field of force like any other compass, but the difference lies in its use of the known and charted Isogonic lines, which are imaginary lines joining places on the earth's surface where the magnetic force of the true north Is the same." Mr. Jones pointed to a wall map In the Mitchel field operations office, showing charted lines running south in irregular waves from the magnetic North pole. "We know where these isogonic lines are. They don't change position," posi-tion," he said. "The new compass has two coils on either side of a rotor. Before making a trip the navigator plots out his course by the Isogonic lines and then sets his instrument In the relative position to these lines that he wants to travel. Then on the drift Indicator he makes his allowance for wind and they set "ft. Whenever the pilot gets off the set course that Is, gets out of line with the navigator's isogonic route the field of force in Ihe instrument's coils Is cut and current cur-rent is set up. "This is recorded on a dial in front of the pilot. An index needle that should point straight upward falls to one side and all the pilot has to do Is maneuver his plane to right the needle ' sgain. Simple as the A B Cs." |