Meridian Park Bison Cache Traditional Cache
abeckett: Opening area for another cache.
Meridian Park Bison Cache
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With all the independent maps of America’s coastline, the determination of precise longitude in America was one of the first steps in building a 19th Century Geographic Information System, making all the Coast Survey maps relative to the world.
With the invention of the electromagnetic telegraph by Crooke and Wheatstone in England, and perfection of Samuel Morse’s version in the U.S., the Naval Observatory in Washington D.C. and the U.S. Coast Survey began experimenting with timing star passages between local meridians via electromagnetic signals over the telegraph lines. In 1851, the Harvard Observatory (the cardinal point of longitude in the U.S.) was connected to the Thomas Hill Observatory in Bangor, Maine, and the longitude difference determined there. Similar work pushed south towards Louisiana. In 1857 we saw the push from Bangor to Calais, and the setting of the stones at Calais to support the clock and telescopes, which are still on the grounds today.
William Brydone Jack, Astronomer at King’s College Observatory in New Brunswick, visited the Coast survey for the 1857 observations at Calais to view and report on the "American Method" of telegraphic longitude determination. Jack also exchanged several star signals with Fredericton. The American Method entailed a written record on a drum register showing time ticks and star signals to the hundredth of a second. Jack had only been using the "eye and ear" method as his finances did not allow for such precise equipment.
Chronograph: Recorded time ticks from the Astronomical Clock, and the star signals placed when the observer tapped a telegraph key when the star crossed the vertical wire in the telescope.
When the ship Great Eastern landed the Transatlantic Telegraph Cable in 1866 spanning the Atlantic from Ireland to Newfoundland, the Coast Survey sent two men to Calais, two to Newfoundland, and two to Ireland. The telegraphic longitude difference was determined across the Atlantic first, but the telegraph lines between Calais and Newfoundland were not good. The situation remedied itself though when a sharp December frost through the lines produced a near perfect connection! Final observations of telegraphic longitude determination were completed on December 16, 1866, at the Calais Observatory.
In 1904, longitude determined by telegraphic means encircled the Earth, closing the angle less than one second (time) from all the independently adjusted observations. Before telegraphic longitude, "time" was physically transported between Liverpool and Boston via "chronometer crossings" on steamers. Later advances included time via wireless telegraphy, and then shortwave time signals. The shortwave method did not require meridian differences to be determined, as Greenwich Mean Time was provided directly to the survey station site. It is interesting to note that some sort of optical astronomical observations were still needed up until the advent of the 1980’s Navstar GPS system of satellites.
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