The 1953 correspondence, which was written from several different base camps, describes such things as the preparatory and acclimatisation work required prior to the ascent of Everest, weather delays affecting the establishment of the ascent route, Hillary's high opinion of his climbing team and his concerns over the experimental nature of the oxygen equipment he will be using. Contained in one of the letters, dated 20 May 1953, Hillary outlines his wishes to his brother Rex concerning the care of their mother and the fate of his climbing gear, should anything happen to him during the Everest expedition.