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.