"One of our many rigid airships. She has 17 gas bags and carries a crew of 20 with the usual war material. The machine gun platform can be seen on the top and is reloaded by climbing the shaft between the gas bags. The corridor it will be noticed runs the whole length of the ship." # 23" A rigid airship is a type of airship (or dirigible) in which the envelope is supported by an internal framework rather than by being kept in shape by the pressure of the lifting gas within the envelope, as in blimps (also called pressure airships) and semi-rigid airships.[1][2] Rigid airships are often commonly called Zeppelins. Rigid airships were produced and relatively successfully employed from the beginning of the 1900s to the end of the 1930s; their heyday ended when the Hindenburg caught fire on May 6, 1937. "M" Series Images taken during the Great War (1914-1919) in England, Canada, and with Canadian Expeditionary Force troop transports crossing the Atlantic. This series was intended to complement the "O" series images taken at the Front.