Broadcasting Penetrates Into Cave

Radio Record, Volume III, Issue 26, 10 January 1930, Page 11

Broadcasting Penetrates Into Cave

SNUGLY lodged in the deep récesses . of the Mammoth Cave, in Kentucky, with a superheterodyne receiver and loop antenna: set up beside them and seventy-five feet of: sandstone rock above their heads, two graduates of. the McGill University, Montreal, Canada, recently listened-in on radio programmes from American stations. They . were experimenting to find to what extent radio waves will penetrate_ rock. With a 300-foot .aerial, coupled to. the loop of the set, the programme was distinguishable through 300° feet: of rock. Similar experiments previously had been. conducted. in the Mount Royal Tunnel at Montreal. ‘In both the cave ‘and the tunnel it was, found that highfrequency stations could not be ‘tuned in, but that low-frequency stations came in loudly. The’ reception was hardly as strong as that ‘in the open air, however. — &