Myths About Finding Longitude


Learning how to find latitude anywhere in the world took far more knowledge than finding longitude. To create the techniques for finding correct latitude in an unknown location, its inventors needed to know:

  • astronomy
  • mathematics
  • have an accurate solar calendar
  • be able to predict the precession of the equinoxes
  • determine local noon correctly
  • invent a scientifically accurate instrument to take the height of the sun at local noon
  • correlate the sun's height at local noon with the position of the sun in the ecliptic
  • realize that they needed all this knowledge to correctly establish latitude anywhere in the world

Finding longitude, you need a pair of clocks. Period.

That was easy.

So why do people think that finding longitude was harder? Because the solution for longitude occurred in England (and in English). Most people read English. Very few read Portuguese, Hebrew, and Arabic, the languages of the sciences used to discover how to precisely determine latitude.

By 1514 Portuguese experts realized that precise longitude would demand accurate clocks on board ship.

So why did it take so long to make the clocks? It was not necessary to have accuracy in longitude--until ships with steam power began to travel very fast in an east west direction. Then they needed precise longitude.Or at least it was a good idea.