During the early stages of the development of aircraft in the pre-war days it was realised that wireless communication would provide the only satisfactory means of maintaining contact between an aeroplane and the ground. Although the technique of wireless was in its infancy at the time, it must be remembered that the needs of aviation in this respect were correspondingly limited; pilots of early types of aircraft had their time fully occupied in keeping their machines in the air at all, and had no energy to spare for communicating with persons on the ground.