I will describe some interesting work that was done in the First World War by S. Keith-Lucas who, like many of us, had been called up from his university to work, during the war, in what is now known as the Royal Aircraft Establishment, at Farnborough.

After doing some experiments in flight, with ordinary compasses, he designed a special compass with which pilots could maintain a straight course and navigate, quite accurately, in clouds.

It was early in the war that many pilots told us that, in clouds, their compasses went all wrong and pointed in almost any direction.