Letter from R B Boardillon, National Institute for Medical Research, Hampstead, NW3, to [Henry Dale], President of the Royal Society Letter urging consideration of his proposal for detecting ships near enemy coasts. Suggests that mine-laying submarines should be adapted to lay submarine cables to points within a few miles of enemy coasts with hydrophones on the end. Notes that radiolocation has not been sufficient to detect the Scharnhorst and Gneisenau. 3 March 1942