This folder contains correspondence pertaining to the "Edison Effect"the flow of current between a hot filament and a positively charged surface, first described by Edison in 1880 as an "electric carrying" phenomenon and mentioned by him in U.S. Patent No. 248,418. The documents for 1917 deal with the relationship between the Edison Effect and the thermionic valve (vacuum-tube diode) invented by John Ambrose Fleming in 1904. Included is a manuscript letter drafted by Edison to be signed by William H. Meadowcroft and sent to the editors of eleven technical journals, reminding them that Fleming's invention was based on Edison's earlier work. Also included is a list of periodicals to which the letter was sent, as well as the four replies received in response. A carbon copy of Meadowcroft's typewritten letter to the Scientific American has been selected as a sample. Identical letters addressed to the ten other journals have not been selected. Courtesy of Thomas Edison National Historical Park.