in other countries. It is comparatively rarely that a weapon is brought into use by one country without it having at least been considered by others. The reason for the one country using a weapon before the others may be due to a more urgent demand in that country or to a superiority in military research departments. Nevertheless, a good Intelligence Service would always be watching for indications of entirely novel weapons or methods of operation, and by maintaining a good knowledge of academic and commercial research everywhere and of Service research at home, much of the field of the first two stages can be covered.