Correspondence from D.W. Heightman to Edward Appleton, 1936-1945

Correspondence from D.W. Heightman to Edward Appleton. Heightman was a radio broadcaster (G6DH) who observed the 'hissing phenomenon' in 1936 and corresponded with Appleton, and with Wireless World, on the subject. In 1945, further correspondence ensued and Heightman's letter of 6 July 1945 encloses observations noted 1936-39. Appleton acknowledged Heightman's early observations in some of his later writings on solar noise.