Letter, from Henry Oldenburg to Christiaan Huygens, dated at London Concerning work on the theory of motion and that he was going to publish Wren's paper on this subject; asks for permission to publish Huygens's paper on the laws of motion; that Robert Moray was going to send all that he has regarding the dispute between Huygens and James Gregory but hopes that it is ended now Postscript wishes Huygens to write his discovery in cipher and transcribes Wren's cipher 4 February 1669