Edit made on October 27, 2016 by MichaelJones at 15:13:46
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The problem of determining one's position around the world in
This was regarded as one of the major technological challenges
in the 18th century, and many of the world's great minds were
focussed on it, including Leonhard Euler and Isaac Newton.
Many suggestions were made for solving the Longitude Problem,
but in the end it was solved by John Harrison's clock, the H4.
By knowing both local time and the time on the Prime Meridian,
the difference gives the longitude. Since the Earth rotates
once every 24 hours, 24 hours must equate to 360 degrees of
longitude. Therefore 1 hour is 15 degrees, and 4 minutes is
one degree of longitude. Thus 1 minute of time difference
equates to 15
arc-seconds arc-minutes of longitude.
To put this in context, 4 seconds difference in time equates
to one arc-minute, which at the equator is 1 Nautical Mile.
To keep time to better than 4 seconds total in a journey of
perhaps three months, in varying temperature, pressure, and
in potentially very rough seas, was thought impossible by many.
It was for this reason that using the stars was considered to
be the only practical solution.
They were wrong.