'The Fourth Arm in the Great War: French Air-scouts at work', First World War, 1914-1918, (c1920). 'A powerfully engined French biplane as used for detailed reconnaissance. The pilot is at his control-wheel: one of the two observers is studying the land below through his field-glasses, while the other is throwing earthward, over the French lines, and in a small tube, a written report as to what has been seen. This tube is visible as it falls, bright-coloured ribbons being attached to it, and when it is retrieved by the nearest troops, - who are warned to be on the look-out for such messages from the sky - it is borne swiftly to head-quarters.' From "The Great World War - A History" Volume I, edited by Frank A Mumby. [The Gresham Publishing Company Ltd, London, c1920]