A meeting of the Technical Committee was held on 9 January in London, at a session which was open to Members of the Institute and to various other people by invitation. From the Chair Wing Commander E. W. Anderson explained that the object of this kind of meeting was to enable the Institute to consider more or less informally matters which were in dispute and to give all Members an opportunity of attending these discussions. The subject under consideration had been discussed, sometimes with vehemence, at meetings, in private correspondence, and in The Journal but agreement among the contestants seemed no nearer. An exchange of views at a technical session might be fruitful. In this account of the discussion, written contributions not presented at the meeting have been included.