5925239 ?The well camouflaged spotter of enemy batteries?, 1917 circa (b/w photo) by Unknown photographer, (20th century); National Army Museum, London; (add.info.: ?The well camouflaged spotter of enemy batteries?, 1917 circa. Photograph, World War One, Air Operations (1914-1918), 1917 circa. Two French observers prepare to rise up in their balloon basket. Their job was to spot enemy artillery and troop concentrations and then use a telephone to direct their own guns on to them. The basket of this balloon is fitted with a machine gun for defence as spotters were regularly attacked by enemy aircraft. Observers also used primitive parachutes. One of 193 British and Allied official photographs taken on the Western Front.); by National Army Museum ; out of copyright.