Fonds consists of personal records, 1918-1919, 1979, 0.01 m; diaries kept during his employment with the Dominion Observatory, 1919-1955; 1.14 m, personal diaries 1921-1937, 1943, 0.2 m; and colleagues' work diaries at the Dominion Observatory, 1932-1948, 0.25 m. Henderson's personal correspondence with his wife, Adella Goldsmith and his mother Olive P. Henderson 1909-1941, general correspondence and invoices 1920-1944; 0.27 m. Order chits for grain and flour from the Wakefield Mill, Wakefield QC, 1924-1925, 1927; 0.08 m.
The fonds also contains photographs taken by J. P. Henderson, illustrating aircraft in Ottawa and skiing activities.
Henderson, Judson Pulford, 1891-1986 : J.P. Henderson, astronomer, was born in Toronto, 2 March 1891. He demonstrated an interest in mechanical and electrical devices at an early age. He obtained a M.A. in Physics and Engineering at the University of Toronto in 1916.
He came to Ottawa in 1919 to work at the Dominion Observatory. Soon after his arrival, Henderson began working for the Time Service section which was responsible for time keeping in Canada. Henderson helped develop the observatory's reception of time signals broadcast from the USA and Europe for comparison against their own time standard. Time signals were also useful for determining longtitude especialy in the north and Henderson was sent to the Mackenzie River area in 1921 and 1922 to pick up time signals for survey parties. The success of this technique led the Dominion Observatory to send out time signals to an Ottawa radio station in 1924 and then to broadcast its own signal in 1928.
Henderson developed compact radio receivers which picked up shortwave time signals. He also continued to make improvements to the Observatory's transmission facilities. In the mid 1930s, Henderson was concerned with measuring delays in sending out time signals and devising more efficient relays. During the Second World War, he was occupied with sending out time signals to an increasing number of users such as the Canadian Broadcasting Corporation, Canadian Pacific Railway, Canadian National Railway and Department of Transport. After the war, he again worked to increase the power of the observatory's radio time signal and helped set up a talking clock service. J.P. Henderson retired from the Dominion Observatory after 37 years of service in March 1956. He died in Ottawa on 16 May 1986.
Henderson was involved in a number of activities in the Ottawa area such as skiing and aviation. He was the owner and operator of the Wakefield Mill in Wakefield QC from 1941 to 1962.
