In my little book, An Approach to Winged Flight, published in 1928, I advanced the view that the flight of all human gliders might fairly be regarded as a winged flight with locked wings.

I suppose that if the wings were unlocked they would flap upwards and the aviator would come down; but that if they could be unlocked and yet restrained by springs so strong that, until any other force were applied, they would retain their horizorital position, then it seemed credible that their movement would be under the control of the aviator and that, as soon as he knew how to exercise that control to his own advantage, he would actually be flying.

The first requirement in any manufacturing process is to secure a stable raw material, and to this end scientific control was essential, for it was found that the rubber obtained from trees on the top of a hill differed from the trees in the same field or plantation at the base of the hill. A process of blending was therefore essential.

The pure rubber was rolled and crushed so that it became a “ flannelly ” sheet of crêpe rubber such as is used on tennis shoes, etc., but in this form the rubber becomes sticky when heated. Filling agents are therefore added, and colouring materials to give the red tint for inner tubes and grey for outer covers.

I have, for the second time, the honour of addressing you. Four years ago I told you how I had had the good fortune to discover a new method of flying with characteristics altogether different from the conventional aeroplane.

To-day, taking advantage of your kind invitation, I come to tell you of how the crude experimental autogiros of 1925 have been developed into practical flying machines. I will also deal with a number of theoretical points in justification of the assertions I have often made about the qualities of the autogiro and in answer to the criticisms of which my system has been made the object from time to time.

The ground covered by the Compagnie Generale Aeropostale comprises thefollowing:—

• 1. The main air line from France to Chile via Toulouse, Casablanca, Saint Louis, Natal, Rio de Janeiro, Buenos Aires, Santiago.

• 2. The tributary lines: Bordeaux-Toulouse; Marseilles-Barcelona; Buenos Aires-Asuncion; Buerfos Aires-Commodore-Rivadavia.

• 3. The line Marseilles-Algiers.

• 4. The line Paris-Biarritz-Madrid.

British aircraft engineering has reached a stage in its development when one is safe in saying that:—

• (a) The aerodynamics of flight is appreciated and understood to a satisfactory extent;

• (b) The methods of determining the loads likely to be present in the primary structural members are reliable;

• (c) The change over from wood to metal construction is, for all practical purposes, a reality; and

• (d) Suitable ferrous and non-ferrous materials of construction available for use by aircraft constructors have been standardised and proved to be reliable and consistent in quality.