Letter from Thomas Gold to Dr Peter Goldreich, Department of Geological Sciences, Mudd Building, California Institute of Technology, Pasadena, California Enjoyed his day at CalTech, and the tidal conversations, Many of the points they discusse became clearer in further discussions with Walter Munk and his colleagues. His two major points were accepted there - magnitude of drag independent of details of dissipation; dissipation oprobably of water against water, not against floor. Discusses the difficulty fo the problem. 17 March 1975