Textual evidence and illustrations of various early rocket launchers are found in the 1510 edition of the Wujing Zongyao translated by Needham and others at Princeton University.[5] These chambers could be fixed to the ground for horizontal launching, secured to a folding copper tripod for high angle fire or mounted on frames on carts or the decks of warships.In the United Kingdom, solid fuel rockets were initially used in the anti-aircraft role; the 7-inch Unrotated Projectile was fired from single pedestal-mounted launchers on warships and a 3-inch version was used by shore based Z Batteries, for which multiple "projectors" were developed.Later developments of these weapons included the Land Mattress multiple launchers for surface-to-surface bombardment and the RP-3 air-to-ground rockets that were launched from rails fitted to fighter bomber aircraft.The first pods were developed immediately after World War II, as an improvement over the previous arrangement of firing rockets from rails, racks or tubes fixed under the wings of aircraft.