At 05:22 PM 11/16/99 -0800, Ryan Weh wrote: >One question if anybody can answer--when was the analemma realised? That >is, there must have been clocks that were known to be accurate, in order to >prove the effect. Was it at this time that the phenomena was discovered, or >was it discovered/would it be possible to be understood before then? > Hi Ryan,
I believe that the first "Astronomer Royal" John Flamsteed (1646-1719) was the first derived accurate tables for the Equation of Time. See <http://www.swan.ac.uk/astra/astro/flamsteed/flamsteed.htm>. He founded the Greenwich Observatory. The royal support for construction came from Charles II as the "Longitude Problem" became critically important for navigation. Time is the essence of the determination of longitude so knowing the difference between solar time and star time was the first step. Flamsteed is famous for the accuracy of his observations. To aid in determining the Equation of Time, he utilized two mechanical clocks with 13 foot pendulums and a micrometer on his telescope. His accurate star charts formed the basis for astronomy and navigation to this century I doubt that Flamsteed was the first to note the difference between sun and star time. In the second century, Ptolmey noted in "The Almagst" that there was a time difference with longitude in the time of eclipse observations. >From this and other observations he concluded that "the earth, taken as a whole , is sensibly spherical". His observations and this conclusion were correct. Too bad he also concluded that "the earth is in the middle of the heavens and the earth does not in any way move locally." However Ptolmey's theory of the universe and mathematics work quite well for sundial design. Roger Bailey N 51 W 115
