Global Positioning System Reference
In-Depth Information
INTRODUCTION
Point of Departure
From rural western Canada to New York City, it didn't occur to me that the
airplanes flying my wife Jane and me across the continent applied the latest
in navigational technology, really an accumulation of millennia of knowl-
edge. Nowadays, traveling over a significant fraction of the earth's surface
involves no great mental or physical e√ort on our part. We pay our fares,
take our seats, and ruminate more on the inconveniences imposed by
Homeland Security than on the marvels of flight or, the subject of this
topic, of navigation. The latter struck home on a much shorter journey,
when we needed to reach a small art gallery in Brooklyn from midtown
Manhattan. Perhaps it is not surprising that we were completely incapable
of the feat. We were gawping up at skyscrapers instead of the more familiar
red cedars of home and were overwhelmed by the bustle and vibrancy of
the big city, a classic illustration of two hayseeds in from the sticks. More
surprisingly, our cabbie also did not know his way around; he turned to his
dashboard GPS system to flawlessly guide us.
Three thousand years ago, humans developed the ability to move long
distances by sea—and the need to get back home again. We as a species
were no longer simply wandering aimlessly from place to place, gathering
food as we went, and moving on when we had exhausted the local supply.
Three thousand years ago, during the Bronze Age, we had well-established
cities and ships and trading structures. At first, we tentatively felt our way
along familiar coastlines. A few—I will tell some of their stories—ven-
tured farther afield and were able to find their way back home. These
epic journeys formed the stu√ of legends, and yet today they would take
only a few hours and involve negotiating nothing more hazardous than a
chicken sandwich.
Navigation can be defined as the science (perhaps initially an art) of
