reply to post by ArMaP
I think Lisbon is a beautiful city, with wonderful food....but I won't go into the Political ramifications...(except to say....from what I've
learned, the Portuguese were the NASA of their era....the Portuguese sailors were innovative, learning how to navigate --- besides using the Stars for
latitude, learned how to navigate longitudude as well....using accurate clocks...)
For the navigationally-challenged in the audience, allow me to explain:
As I mentioned, a ship in the 15th or 16th century could sail, along a course, using the compass and nightly star sightings, in order to stay true to
course....East and West. Problems developed, in those days, when they attempted to sail North/South, when out of sight of the Coastline.
You must recall that at this period in history (the 15th century) trade with Asia was difficult, overland. Some trade was accomplished by sea, but
required a long voyage, by ship, around the horn of the Asian Continent, and back. This was accomplished, in that era, by staying within sight of the
shore, and using the stars to determine the latitude....those are what you would consider the 'horizontal' bands around what we now know is the
The ability to exceed the sight of land, and to investigate the currents that existed in the Oceans, and then return safely to one's origin....well,
the Portuguese were instrumental in this endeavor....that's why I refered to them as the era's 'NASA'.
How did they do this?? It involved a top-secret device (at the time) that actually involved....time! It required the invention of a time-piece that
could actually keep time on a a ship's-deck, even as the ship was tossed at sea. See, THIS is how degrees of LONGITUDE could be measured, in those
Remember, LATITUDE can be considered as the horizontal bands around a spherical planet....usually defined as begining at the Equator, then
theoritically slicing through.....at equal spacings, much like a Layer Cake....
LONGITUDE is a bit more complicated, though.
NOW, before you slice that orange, let's put it up, so that the 'core' is now vertical...different from the last example...but, imagine we have
ALREADY sliced it into micro-thin slices, as described before, but he haven't taken it apart yet.....because he have more slices to make.
Let's pause, for a bit, imagine the Earth as that Orange....after we've done the 'theoritical' cuts....let's change those 'cuts' to just lines
on a map....OK?
NOW....it is Well-Known that Latititude can be determined based on heading, and star-sightings. ("latitude" is...how far North or South you
Longitude, well, in the old days, before GPS....depending on your known latitude at the start, and heading and speed, you would NOT know your
'longitude' with any accuracy, since it was dependant on heading and speed, from your last known position. See...'speed' was the
problem....hence, we have the term 'knots'....something the British Navy invented, I believe....essentially, a rope, previously tied into knots, was
deployed aft of a vesell, and the 'knots' were counted, as they went over the transom....again, with no accurate timepiece!!!!!
Back to the problem of arraying co-ordinates on a Globe! See, you can slice the Orange, as I indicated before....that would be the Latitudes.....but,
what if you took the SAME Orange, and cut into it the different way??
Take a different orange (because we've bollocked the first one, but keep it in mind, nonetheless) and take this new orange, and stand it on its stem,
then slice it down the middle....and keep slicing, AS THIN AS YOU CAN, keeping the core up the middle....what you imagined is how the LONGITUDINAL
lines bisect the imaginary Earth......
Let's put all of this together, in our minds, and picture for a bit....
Step away, in you mind, from the Earth, and picture the Orange....
Sliced laterally, and then vertically.....THESE are the 'virtual lines' that have been 'drawn' on our Globe, which we call 'Earth'
If you live in parts of Great Britain, then you live in WHAT IS REFERED TO as the 'Meridian'...or "GMT"...'Greenwich Mean Time', or, as the
French like to call it, "UTC", or 'Universal Co-Ordinated Time'.....(In French, the 'UTC' makes sense, as in...well, you'd HAVE to look up the
French translation).... but, it's the same thing. I mean, when you see 'GMT' and 'UTC' in the same paragraph, they mean the same thing......