From Sandy Henderson, Dunblane, Stirling, UK
Lu mentions exploiting the buoyancy of an airship to propel it by storing compressed air and using it for thrust. Your columnist Daedalus (David E. H. Jones, 1938-2017) had a more elegant solution with his thermal “glidoon” (). He proposed effecting buoyancy change through the condensation of ammonia. Some drones at sea now use this technology.
Some of your other recent reports also touch on things he discussed. For example, Jones prefigured your story on a generator that runs on heat escaping to the sky (21 September, p 17), describing it as an “anti-greenhouse” (3 March 1966, p 562); and also discussed the effect of electric fields on crops (24 August, p 42, prefigured on ). It would be nice if you gave him a bit more recognition.
