In a cleft in the limestone bluffs on the south bank of the Ottawa River just downstream of the Chaudière Rapids, British soldiers and civilian labourers are starting to build a canal that will allow boats to travel between Montréal in Lower Canada and Kingston in Upper Canada without fear of American attack. Surveyed, designed, planned and built by the Royal Engineers (Lieutenant-Colonel John By in command), the military canal links a tangle of rivers and lakes to form a navigable waterway 200 km long and at least 1.5 m deep. The herculean project is directed by LCol By from his camp on the Ottawa River, which is already attracting settlers.

LCol By arrived in May, called out of retirement in England because of his experience building locks on the St. Lawrence River and strengthening the fortifications at Québec. He and his officers and men spent the summer exploring the almost trackless wilderness, surveying the first sections of the route, and importing contract labour: Scottish stonemasons and Irish "navvies" capable of shovelling 7.5 m3 of earth per day. Planning, surveying and administration will be done in winter; the summers are for building. With hand tools, gunpowder and oxen, the navvies and masons dig and build their way through virgin forests and mosquito-infested swamps. They suffer terribly from disease, especially malaria, which is often fatal.

When it opens in May 1832, the Rideau Canal is a marvel of civil engineering: with its 47 locks and 50 dams, it raises boats 83 m from the Ottawa River to the portage channel at Newboro, and lowers them 54 m to Lake Ontario at Kingston. The bill is terrifying, however: £1 million-the most spent by Britain on any project in the Canadian colonies. LCol By is summoned home in 1832 to face allegations of unauthorized expenditure, and he dies, a broken man, in 1835. 

Back in Upper Canada, his main camp becomes, first, a village called Bytown, then, in 1855, the city of Ottawa.

"Fourth Dimension" is a regular feature written for the Canadian Forces
newspaper The Maple Leaf, published by the Department of National Defence.