Here is the gist of my three “theorems” (I hope the self-irony is appreciated). Suppose that we wish to locate Ottawa. A message is sent out from a point somewhere deep beneath Ottawa. It arrives first in New York and then in Moscow. What can we say about this observation? Let us bisect the arc New York–Moscow. We may state confidently that Ottawa is in the hemisphere that contains New York, not in the one that contains Moscow. How so? Because the great circle that bisects the arc New York–Moscow is the locus of all points that are equidistant from...

First Page Preview

First page PDF preview
You do not currently have access to this article.