The state highway department in Pennsylvania once set out to build a bridge working from both sides. When the workers reached the middle of the waterway, they found they were thirteen feet to one side of each other. Albert Steinberg, writing some time ago in the Saturday Evening Post, went on to explain that each crew of workmen had used its own reference point. No wonder they did not connect.

In that same article Steinberg tells about a small disc on the Meades Ranch in north central Kansas where the thirty-ninth parallel from the Atlantic to t…