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In 1788, Alexander Aitken (sometimes spelled Aitkin), a deputy surveyor, had prepared an initial survey of York Harbour on the instructions of the Governor-in-Chief, Lord Dorchester (Sir Guy Carleton, First Baron Dorchester). In 1793, he was asked by the Lieutenant-Governor of Upper Canada, John Graves Simcoe, to prepare a new survey, which included the proposed location of a blockhouse to command the entrance of the harbour, as well as a battery and barracks for the Queen’s Rangers. The soundings for this survey were taken by Joseph Bouchette.