The following Paper comprises some of the results of an investigation originally undertaken by the writer to determine the effects of the humidity of the atmosphere and other secondary factors upon the static lift of airships. It is almost invariably found on completion of such a craft that a considerable deficiency is revealed between the designed lift and the apparent value deduced, for example, from a “ lift and trim ” trial. Clearly, it is of considerable importance that the reason for this discrepancy should, if possible, be determined; for whilst the loss may be only a small percentage of the total displacement of the ship, and hence difficult to trace, yet considered in terms of disposable lift, it frequently is very serious.

The attainment of the mighty speed of 379 miles an hour by an officer of the Royal Air Force (Flight Lieutenant Stainforth) is fresh in our minds and we honour the pilots, the aircraft builders and the engine constructors who made this possible. We remember also, I hope, the scientific workers, whose investigations afforded the basis on which so much else was built. When one contemplates motion at such speeds as this, one cannot help speculating where such enterprise will lead. The power to move is not new; railways and roadways give abundant evidence of high speed, but motion along them is almost entirely in two dimensions. It is only when the freedom of the air makes three-dimensional motion possible that the problem appears in its greatest and most interesting aspect. In the air there is combined the greatest possible freedom with the highest possible speed, and it is this combination which makes the study of such intense scientific interest. Moreover, the flight path may be greatly curved and that curvature may be in any plane. Great forces may then arise and act upon the aircraft from any side. It is not for nothing that the pilot is strapped into his seat.

If the amount of printed matter published on a technical subject is any guide to the general state of knowledge on that subject, then neither the turbo-compressor nor the general problem of the supercharging of aircraft engines can be very well understood at present, much less the combination of the two. Apart from the brief treatment accorded to the behaviour of engines at high altitudes, and supercharging in the well-known text-books on engines, the only printed matter available on the subject is contained in papers published in technical journals (so far as one knows), viz.:—

“ Supercharged Aero Engines,” R. F. R. Pierce, the Journal of October, 1926.