Page:Popular Science Monthly Volume 90.djvu/248

 The Wireless Detective

How transgressors of national and international Radio laws are caught

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��A "Radio Detective" which not only picks up passing wireless messages but also determines the direction from which they come and the probable location of the sender

��EVEN in times of peace it is often of importance to locate wireless sending stations. When an amateur's station is transgressing national law, or a spying government's station is transgressing inter- national law, a "radio detective" will be of valuable assistance to our government. But in time of war, an instrument that can not only intercept wireless messages but can also locate the senders, will be of great strategical importance.

The photograph above shows such an instrument which has been brought out by Frederic Koester, a young experimenter in the United States Bureau of Standards, of the Department of Commerce. The ap-^ paratus picks up the passing radio mes- sages and, at the same time, indicates the direction from which they come. By listening to the same message with two instruments of this kind placed at two different points, the position of the sender may be definitely determined. It is neces- sary only to mark on a map the two posi- tions where the instruments are receiving the message and to draw two straight lines in the directions shown by them. The place where the two lines cross on the map will indicate the desired spot.

��Motion-Pictures Tell South Americans of Our Industrial Development

TO acquaint South Americans with the industrial development of this country and particularly to educate them in typical American manufacturing processes, wel- fare work in industrial institutions, and other details of economic life, the commer- cial attaches in the Latin-American coun- tries are exhibiting motion pictures in their respective localities.

The pictures are being given under the auspices of the Bureau of Foreign and Domestic Commerce, but the films are obtained through the Bureau of Commer- cial Economics, an unofficial organization with headquarters in Washington, which has on hand a large number of films showing various phases of American industry. The films which the Bureau thinks most desirable are sent to the commercial attaches.

In addition to educating the South Americans along American industrial lines, one purpose of sending the films is to stimulate interest in a much more extended campaign by which American manufac- turers may have their films displayed for advertising purposes.

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