22-Jul-1999 -- While the definition of latitude dictates where the latitude lines run (0 degrees at the equator up to 90 at each pole), the location of the longitude lines is entirely arbitrary. Any point on the globe could have been defined as 0 degrees longitude, with all of the other points following from that initial landmark. When navigation by latitude and longitude was being developed, there was quite a controversy about the choice of where the zero line would be set. France, of course, wanted it to run through Paris. Great Britain, however, had the world's mightiest naval force, and since naval navigation was the original impetus for the development of the whole system, England prevailed. The zero line was set to run through the Royal Observatory in Greenwich, England. While visiting London last summer, my wife and I decided to make the short boat trip down the Thames River to Greenwich in order to experience the birthplace of longitude first hand.

Photo #1 shows the Royal Observatory Complex, situated on a high hill on the outskirts of Greenwich. The observatory itself is on the left. The red ball on top of the dome to the right once served as England's official timepiece (a key aspect of successful navigation by sea involved the use of precision timekeeping devices, a field in which Britain also excelled). Even now, the ball drops down the pole every day, indicating the precise moment of noon, Greenwich Mean Time. This tradition is emulated most famously in Times Square, New York at midnight of the New Year. Under the large tree in the center of the picture is the marker for the zero longitude line. The inset shows an image of my GPS receiver taken in a pub at the foot of the hill. Photo #2 shows several old standards which are kept at the observatory. Instrument manufacturers could travel to Greenwich to calibrate their instruments to the standard British yard, other units of measure, and also to timing and altitude standards. The world's first electric clock is mounted in the wall. Photo #3 shows the demarcation of the hallowed line itself. Our well-adjusted English cow puppet demonstrates how to straddle the hemispheres! Photo #4 is a shot looking south from the observatory down the line. The Millennium Dome, a huge, billion-dollar arts and entertainment center being constructed to celebrate the year 2000, can be seen in the distance. It is also situated on or very close to the zero line. Finally, Photo #5 shows the latest in timekeeping technology, an atomic clock, also housed in the observatory. This clock, along with its counterparts elsewhere around the globe (including Paris, France and Fort Collins, Colorado), reflects the world-standard "Coordinated Universal Time", which serves as the true heartbeat of the modern world.