Mark (another AHD who has daughters at the same school as Chloe) and I made our way over to Greenwich this morning to check out the Royal Observatory and see the Prime Meridian, where East meets West (longitudinally speaking.)
"Why a midweek visit?" one may ask. I had an interest in seeing it, and am the only one in this family with such an interest. So it was just better for everyone this way. There's nothing concrete planned, but I suspect there will be more of such excursions and blog posts over the next 8+ months. Anywho...
A good bit of the exhibition space at the Royal Observatory was devoted to -- in both terms of the need for, and the instruments used to determine -- the Prime Meridian (or that imaginary yet arbitrary line that runs between the poles and separates East from West.) In a nutshell, it came about largely due to maritime concerns... ship captains had ways to determine their North/South latitude (e.g. by measuring the angle above the horizon of the sun at 12 noon) but were stumped about how to determine their East/West location.
Solving the "longitude problem" became the quest for many over many decades. One "solution" that was offered involved the Powder of Sympathy, and the theory goes like this: this Powder was to have amazing healing powers. Those who believed in felt it could cure wounds from afar by being applied to the knife which had caused the wound or to bandages which had been used to dress it, rather than to the wound itself. With that as the foundation, believers in this powder thought all ships should carry on board a dog, and all dogs should be wounded by the same knife. Everyday, someone back in London was to dip this knife in the Powder of Sympathy at 12 noon, causing the dogs aboard the ships -- wherever they may be -- to instantaneously yelp. This time market would let the captains know it was 12 noon in London and, when compared to their local time, allow the captains to calculate their longitude.
Eventually (and obviously), a solution to the longitude problem was found (and surprisingly, it didn't involve maiming dogs), and it came about largely due to a £20,000 prize Parliament dangled out there in the early 1700s.
(Pictures, top to bottom: Left foot in the West, right foot in the East; view of London from the Royal Observatory with Central London highrises on the far left, the highrises of the Docklands in the center back, and the National Maritime Museum in the center foreground.)