Having–honoured me with an invitation to deliver a lecture this Session, the Society intimated that the most acceptable subject would be “Heavy–Oil Engines for Aircrat.” Unfortunately difficulties intervened which prevented the Society's choice from being adopted, and the outcome has been the hurried preparation of this lecture upon a subject which may seem remote from that mentioned.

As regards the broad title, this remoteness is more apparent than real, however, since the difficulties to be surmounted in evolving heavy–oil engines for aircraft relate quite as much to the mechanics of engine design as to problems of fuel injection and combustion. That this is so may be gathered from the paper Mr. Pye read before the British Association last summer, and from Mr. Chorlton's comments in the December issue of the Society's Journal. In Mr. Pye's paper, information is given which shows that much progress has been macfe in this country (and notably at the Royal Aircraft Establishment) in the direction of obtaining satisfactory combustion at high engine speeds with airless fuel injection.