The Rideau Canal, began in 1827, was finished in the winter of 1831, connecting the trade and commerce of the two provinces of Canada, on which, by means of locks and dams, vessels are raised to a summit level of 283 feet in eighty-four miles, and again descend 165 feet in forty-three miles.[274] The object of the undertaking was, in the event of a war with the United States, to have a secure water communication open between the lakes and Lower Canada.[275] Two companies of the corps were employed on this service under the command of Lieut.-Colonel By of the engineers, whose name was given to the town which rose up in the wild spot selected for the headquarters. The earliest hut in Bytown, now a flourishing settlement, was built by the sappers. For the first summer they were encamped on a height near the Ottawa, but before the winter set in were removed into temporary barracks erected by themselves. Most of the work of the canal was executed by contract, but in some parts of the line where the engineering difficulties were great, sapper labour was chiefly resorted to—the non-commissioned officers acting as foremen of trades and overseers. Parties were detached during the progress of the canal to Merrick’s Mills, Isthmus of Mud Lake, Upper Narrows, rivers Tay and Richmond, Jones' Falls, Claffey’s Mills, Newborough, and Isthmus of Rideau Lake. Footnote 274: Speech of Major Selwyn, R.E. ‘Graham’s Town Journal,’ 1842. Footnote 275: ‘Prof. Papers, Royal Engineers,’ v. p. 157. -----