Electron emission

Edison´s observation of the discharge of negative electricity from the carbon filament of an incandescent lamp to an auxiliary electrode in the bulb, commonly known as the “Edison effect,” remained unexplained until the beginning of the 20th century. Since that time, an entire new industry — radio — has grown up as a result of continued research in the emission of electrons from hot cathodes. This article, seventh of a series prepared under the sponsorship of the A.I.E.E. committee on education, reviews some of the more important observations and conclusions obtained from investigations in this field.