American merchant ships, as well as naval vessels, were equipped with modern apparatus and furnished competent operators. Thousands of radio operators were required, and 7,000 were enlisted and trained. At Harvard University we established the largest radio school that ever existed. Beginning with 350 students in 1917, the number grew to 3,400 and operators were graduated at the rate of 200 a week. Air, surface and undersea craft were linked by radio, easily communicating with each other at long distances. Battleships received four messages and transmitted three simultaneously. During the flight of the Navy planes across the Atlantic, in May, 1919, a message was sent from the Navy Department to the NC-4 far out at sea. An immediate reply was received from the plane, and this was transmitted to London, Paris, San Francisco and the Panama Canal Zone, and its receipt acknowledged by these stations, thousands of miles apart, all in three minutes after the original message left Washington. When President Wilson went to France on the _George Washington_ to attend the Peace Conference in Paris, we kept in touch with the ship by wireless all the way across the Atlantic. On the return voyage we made a test with the wireless telephone and from an instrument much like the 'phone in your home or office, I talked with the President when he was 1,700 miles at sea. The radio compass, used first for locating enemy submarines, became a most important aid to navigation. Any ship out of its course or uncertain of its reckoning has only to transmit the signal, "Give me my position." The operator at the radio compass station turns the wheel now this way, then that, until he finds from what point the wireless comes strongest. At the same time other stations along the coast are doing the same thing. Triangulating the directions reported, the master out at sea is told the position of his vessel, the latitude and longitude and, if in danger, is told what course to steer to get out of his predicament. The saving in life and property has more than compensated for the cost of this system. Beginning with a few on the Atlantic, there are now some 75 of these compass stations all along our coasts. The necessity of a single control of wireless was shown by an instance that occurred one night in the Navy Department. A message was being received from Darien, in the Panama Canal Zone, when some one broke in on its wave-length and mixed up words and letters in a hopeless jumble. The operator had to stop Darien until he could find out where the trouble was. At last they found it was a station in Nova Scotia, that was testing its apparatus. It had unintentionally "broken" into the wave-length our operators were using, and caused interference clear to Panama.