The original title put down for this paper was “The Design and Operation of Commercial Aircraft.” I hope it will be observed that I have actually taken a very much more modest title than that. A paper with so broad a title as the original one might well have been read five or six years ago, but at the present stage of development of commercial aviation, he would be a bold man indeed who would attempt to deal with two such subjects in a single one–hour paper.

It happens that the Society has had two very valuable papers dealing with commercial air transport comparatively recently. I refer in the first place to Sir Sefton Brancker's paper of October, 1925, which gave a very comprehensive review of the progress of civil aviation during its first six years, including a general survey of the development of commercial aircraft design. A little later on we had a most interesting paper by Mr. Cowley dealing with the more theoretical aspects of aircraft transport economy.