Correspondence between Barnes Wallis and Hartley Pratt regarding the manufacture of rigid airshops. Primarily consists of letters from Pratt to Wallis. Includes:

- Letter from Pratt to Wallis dated 13 July 1913, marked private and confidential, in which Pratt offers Wallis the position of Chief Assistant at Vickers Limited

- A copy of ‘Popular Science Siftings’ dated 8 September 1914, which features an article on zeppelins on the front page

- Letter from Pratt to Wallis dated 29 September 1915 in which Pratt says the Admiralty have asked him to rejoin Vickers to oversee the design and manufacture of airships at Barrow and that they also want Wallis to rejoin Vickers. Subsequent letters provide further detail about the terms of their return to Vickers

- A letter from Barnes Wallis to the Director of Air Services at the Admiralty, resigning his commission from the Royal Navy Voluntary Reserve in order to take up the post of Chief Draughtsman at Vickers, dated 28 November 1915