A new industry calls for new methods—autrea jours, autres mceurs—and the aeroplane industry is therefore not exceptional in demanding many departures from recognised woodworking practice. In the first place the number of machines required to–day is so large that their construction should be described as a manufacturing rather than a building operation. That is to say, they should preferably be almost entirely put together by the aid of accurate machinery instead of being dependent to such an extent upon the skill of the individual workman, in trying and fitting one part to another until the whole is built up. In this connection it may be remarked that the design of the metal fittings for aeroplanes is not such as to call for any radical departure from previous high class small metal working practice. It is the woodworking side of the business which presents the new scope for initiative. It is this latter aspect, therefore, which will be considered here.

From Captain Hucks’ remarks on the difficulties of keeping a straight course when flying in clouds, and the impossibility of relying upon the compass as a guide when out of sight of a fixed point of reference, it would appear that the nature of the errors to which a compass is liable, and the circumstances under which it may be relied upon are not generally known.

Much work has been done at the Royal Aircraft Factory in the last three years on the behaviour of compasses in the air, and the directions to be followed in their design in order to avoid their errors as far as possible. This work was chiefly done by the late Captain Keith Lucas, F.R.S., who was unfortunately killed when learning to fly, in the autumn of last year. The following is a short statement as to what may be expected from compasses in aeroplanes:—

On account of the dip the N. point of the compass card, when an aeroplane is turning, always tends to point too much towards the centre of the turn, the amount of error varying according to the bearing from which the turn is made.

In applying the methods of rigid dynamics of three dimensions to the study of aeroplane motions, one of the first questions which had to be settled by myself and Mr. Harper in the preparation of “Stability in Aviation” was the choice of co–ordinate axes and the notation to be adopted for the various forces, couples and rates of variation of components of air resistance. Where, as in this case, the necessary symbols more than exhaust the ordinary alphabet, the problem is a difficult one, and it was therefore intended to insert a separate section explaining the advantages which rendered the choice adopted the only logically possible one.

Unfortunately, at the time when “ Stability in Aviation “ was published, very great doubts existed as to the practical utility of any such investigation except as a subject of academic study in orthodox mathematical circles, and the work of preparing the book in the face of obstacles, partly arising from opposition, had proved such a strain that any further discussions on the subject would have been incompatible with my academic duties.