Thirteen years ago, shortly after I had been privileged to supply the British Government with my Electric Signalling Balloon Apparatus, I showed upon the screen of the London Institution the same picture that is now before you. It represents the signallers of two friendly military forces shut in by high mountains. It shows how limited is the usefulness of the ordinary methods of visual signalling, which depend upon some vantage point for altitude; it shows how valuable in such a casa is the electric signalling balloon. In the picture, the signallers on this side of the mountain are filling the balloon with gas for the ascent. On the other side, the balloon has already ascended. In the next picture both balloons have ascended to a considerable elevation, and the signallers are independent of the configuration of the country. I will now ask whether this picture does not partly represent the conditions realised so often during the South African Campaign, when our brave soldiers have been imprisoned so long amidst the rugged mountains of Natal, and where failure of communication has been the cause of disaster.