Letter from Thomas Gold to Dr Martin Rees, Department of Astronomy, California Institute of Technology, Pasadena, California Thanks him for the proof. Gold has indeed sint a corrcted version to the printers. He has no views as to which solution is more probable - the ring being hit be a spherical burst or the sphere being hit by a plane burst. Had thought of both possibillities at the time of the meeting. 20 May 1971