In his opening remarks, Mr. Young stated that the magneto was an electrical machine of very small compass for converting mechanical energy into electrical energy at a very high potential. The electrical energy appears as high tension sparks which occur at regular intervals and in synchronism with the movement of the pistons. Each spark is the result of a very rapid rise of pressure in the secondary winding of the armature of the magneto. To-day magnetos are being produced capable of giving regularly 16,000 sparks per minute or 270 sparks per second.

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.

The paper to be given this evening will describe the methods used and the sequence of operations in erecting a machine which has been delivered new or overhauled from the makers, as distinct from carrying out repair work.

It is proposed to commence with the methods used for checking the correct assembly of components and the rigging of an erected machine. We will assume that a machine has been delivered to the owner in a dismantled condition; that is to say, the wings, tail units, undercarriage and centre section have all been received separately, and it is necessary to entirely re-assemble the machine. It is assumed that the machine is in good condition and that each component has been approved already.

The wind channel and the whirling arm have been devised and perfected over a period of a number of years with a view to providing reliable aerodynamic data for aircraft designers. Of late years the wind channel has been used considerably more than the whirling arm.

In the two pieces of apparatus distinct methods are used. In the whirling arm the model is carried through the air, which is stationary, in a circular path by a long arm. In the wind channel, on the other hand, the model is stationary and a current of air is caused to flow past it.

Various types of wind channel have been evolved, but I intend to describe fully the English wind channel in its present form, as perfected by the National Physical Laboratory and the Royal Aircraft Establishment, Farnborough.