It has been nearly a century since a solar eclipse covered America. It will take four hours and 24 minutes as Earth turns while the moon moves east 2.36 degrees. That may not sound like much, but it was a critical difference in the 16th century when Europeans were trying to accurately map and navigate the world.
The determination of longitude in the 16th century was difficult as the method developed by Phoenician cartographers was secret and vanished into the mists of time. In antiquity Alexandria was ground zero for cartography, map making. They mapped the world with “portolan,” port maps. Continent contours were not determined. They were largely fanciful and became fodder for academicians.
Ancient mariners only wanted to know of ports, the rest of it was scenery and they were not tourists. In boats advancing only 20 miles a day they could die of thirst or starve if they wandered. And, wander they did: Surface winds blow many ways on the high seas. Knowing where they were and going was life or death.
My interest in this began as a boy on a fishing trip to Canada with my grandfather when we saw Phoenician coins in a Duluth, Minnesotamuseum, found there in the 19th century. The Saint Lawrence river was navigable in antiquity when the sea level was higher.
In Columbus’ time longitude was determined by recording local time of an eclipse, then compare it to the local time the event was seen at a home base. In antiquity it was Alexandria, Egypt, in Columbus era Salamanca, Spain and finally Greenwich, England to date.
Every hour of difference is 15 degrees east or west of the base, but for a long time they did not realize they were not seeing the same event in time! For every hour of difference there was a 0.536 degree error. It may not sound like much, but from Salamanca, Spain to the Caribbean was eight hours, 4.3 degrees and a potentially fatal error for 16th century mariners.
Christopher Columbus made two location attempts in the Caribbean missing by 800 miles both times. That he is in the history books as “The Navigator” is a joke.
It is believed error correction was first done by cartographers in Istambul, Turkey early in the 16th century and soon after by Lisbon, Portugal cartographers. Turkish cartographers compiled the Admiral Peri Reis’ of map of 1513 AD from portolan charts drawn between 6000 BC and 3000 BC in Alexandria. It had the outline of Antarctica and locations not in the literature until after 1600 AD.
One of their maps included our Saint Lawrence River confirming what I saw Duluth, Minnesota. It is hard to imagine the Indians having casinos then, but apparently the Phoenicians went home mad, sore losers, never to return.
In a 1974 book project I saw a way the charts could be done using solar-lunar intervals which occur every month and not rarely like eclipses as that would better explain the Phoenician’s abilities. I had a series of visions that were either the way our minds work or were navigations of time. I know not which.
My concept was published in the seventh edition of “The Maps of the Ancient Sea Kings,” by Dr. Charles Hapgood, a leading authority on cartography, then noticed by Smithsonian Institution Magazine editors who were preparing an issue on navigation in antiquity. They asked me to make a contribution and try my method on the work of Captain John Cook who placed islands in the South Pacific so accurately their positions were not improved until satellites were used geographically. Could I show Cook used a similar method?
Meanwhile back at the couch and naps I found Cook and saw flashes of setting up pendulum clocks instead of free pendula used by the Phoenicians, but did not see, or imagine, the work. Nonetheless, I felt I knew what they were doing so I did calculations on one island.
The Smithsonian people wanted confirmation so I found other islands Cook had located and their gravity constants. Where pendula were involved any difference would affect the positions. On my submission the Smithsonian contacted the British Admiralty for confirmation, but were told Cook’s work was a state secret! 200 years later? I suspect they simply did not want to be bothered or have to admit they had destroyed Cooks work, but the matter was unresolved. Thus what I had done was a “speculation” on publication.
Our August 21, 2017 eclipse may not be of importance, but it was once an event on which important men’s lives were in the balance and we note that on the day of the eclipse.