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THE article on the application of conics to the layout of air‐craft by MR CAMPBELL, which we publish in this issue, is the latest of a number, constituting in effect a series on the subject though not designed as such, and has from the insular point of view a special interest because it is the first giving an account of British practice as exemplified by the Blackburn Aircraft Company. The previous two papers, which are referred to in a footnote to this present one, were contributed by members of the design staffs of North American Aviation and Fleetwing Aircraft respectively, and therefore represented transatlantic predilections. The truth is, of course, that there are as many ideas on applying the method as there are firms—if not, indeed, individuals—utilizing it. We have perhaps done our part by introducing some of these and it would become merely tedious to continue reproducing variations on a theme which is by now becoming familiar.