This week, Collected Wisdom is going surveying on its vast country estate. Let's see if we have all the necessary equipment. Theodolite? Check. Field books? Check. Sedan chair and team of minions? Check. Then off we go.
Why is the Saskatchewan-Manitoba border a series of small jogs, rather than being a straight line like the Saskatchewan-Alberta border? asks Don Keith of Waterloo, Ont.
In a nutshell, the jogs are caused by adjustments in the land-survey grid for Western Canada, to compensate for the curvature of the Earth.
When the West was being colonized in the 1800s, says Michael Zawalsky of Cobalt, Ont., the Dominion government undertook a vast project to promote orderly settlement, at the core of which was the Dominion Land Survey (DLS). The basic mapping unit of the DLS is a square tract of land, called a township, measuring six miles on each side, writes Mr. Zawalsky, who is a retired employee of the cartography section at Agriculture Canada.
On the DLS grid, he writes, “latitude lines, which run parallel to the equator, are used as horizontal lines. Longitude or meridian lines are used as vertical lines for the map grid.” Because the Earth is a globe, the vertical lines are not parallel, but gradually get closer together until they converge at the North Poles.
Over now to John Patterson of London, Ont. Due to these converging vertical lines, he says, the width of the southern boundary of a block on the DLS grid is longer than that of the northern boundary. If this pattern were left uncorrected, says Mr. Zawalsky, the converging lines would enclose increasingly smaller township areas as they progressed northward.
According to a 1986 paper by University of Saskatchewan professors Robert McKercher and Bertram Wolfe, this problem was solved in the following manner: Every 24 miles, the vertical boundaries that define the western edges of townships are corrected, essentially by breaking the boundary, moving it 225 feet farther west, and then allowing it to continue on its northward path.
This causes a series of jogs, which increase in size as they progress westward from the beginning of the grid, near Winnipeg. The first jog is about 225 feet, the next is 450 feet, and so on. By the time the grid reaches the Saskatchewan-Manitoba border, says Mr. Patterson, the jog is about 1.25 miles.
In the case of the Saskatchewan-Alberta border, the meridian lying along 110 degrees west longitude was chosen as the boundary. This is one of the points in the system where the grid is recalibrated to follow a meridian, so the border has no jogs.
Here's a follow-up entry to last week's discussion about the origins of the terms “bull” and “bear” in stock-market-speak.
“The original London Stock Exchange consisted of a bulletin board on which offers to buy (bulletins or ‘bulls') were posted,” writes Mel Wiebe of Kingston. Thus, during a hot market, the board would be full of bulletins, or bulls (“bullish”), while during a cooler trend the board would be bare (“bare/bearish”).
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- Why does the water in the toilet move on very windy days? Graham Duncan of Mahone Bay, N.S., wants to know.
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