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Old 26-06-2012, 07:37   #16
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Re: Longitude, Why East or West.

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Originally Posted by SaucySailoress View Post
Quite simply, Greenwich is the centre of the world. Or at least was, when these things were being established. At the end of the day, you either sailed East from Greenwich or left from Greenwich.
Ah... not so simple SS, not disputing that one sailed east or west from Greenwich but why did one measure the position as E or W rather than say 10 longitude or 350 degrees instead of 10 E or 10 W.

Perhaps I could see it more appropriate when measuring distance (not position). Today I travelled 2 degrees E of Greenwich or 2 degrees W of Greenwich, thus it becomes accepted and positional as well
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Old 26-06-2012, 07:41   #17
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Re: Longitude, Why East or West.

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Originally Posted by SaucySailoress View Post
Quite simply, Greenwich is the centre of the world. Or at least was, when these things were being established. At the end of the day, you either sailed East from Greenwich or left from Greenwich.
actually that is not strictly true!
i have a few very old charts where paris is the prime meridian or 0degrees!
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Old 26-06-2012, 07:44   #18
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Re: Longitude, Why East or West.

In the computer age the complexity of computations are irrelevant. Back when you either did it in your head, or wasted precious paper simpler is better.

No one sailed across land, so that left big ocean 1, or big ocean 2.

The higher the number the further you were from home.
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Old 26-06-2012, 07:47   #19
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Re: Longitude, Why East or West.

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Originally Posted by atoll View Post
actually that is not strictly true!
i have a few very old charts where paris is the prime meridian or 0degrees!
Well yes, the French used Paris until quite recently, forgotten when they stopped but IIRC, it was only in the last century or two. Russians (and perhaps Italians ?) had their own prime meridians and I assume other nations also.
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Old 26-06-2012, 07:53   #20
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Re: Longitude, Why East or West.

latitude and longitude could quite easily be expressed as x and y values
ie lat=x 0-180 and long =y 0-360.

so sydney at 33 degrees 51 south and 151 degrees 13 east

would become 123 degrees 51 minutes X and 208 degrees 47minutes Y
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Old 26-06-2012, 08:05   #21
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Re: Longitude, Why East or West.

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actually that is not strictly true!
i have a few very old charts where paris is the prime meridian or 0degrees!
Please don't use them for navigational purposes
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Old 26-06-2012, 08:08   #22
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Re: Longitude, Why East or West.

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Originally Posted by atoll View Post
latitude and longitude could quite easily be expressed as x and y values
ie lat=x 0-180 and long =y 0-360.

so sydney at 33 degrees 51 south and 151 degrees 13 east

would become 123 degrees 51 minutes X and 208 degrees 47minutes Y
Gosh, only one step away from decimalising it Keep this up and we can do away with the whole NSEW thing

Seriously, good point, I hadn't seen how easy it was to convert lat to 180 degress rather than + & - 90
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Old 26-06-2012, 12:43   #23
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Re: Longitude, Why East or West.

Interesting debate. Don't forget that Latitude was measured from the Sun, it was either overhead or at some angle not greater than 90, and was either north or south of you. Hence the equator at the equinoxes was at 0.
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Old 26-06-2012, 13:11   #24
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Re: Longitude, Why East or West.

Comes from analogy with N/S in latitudes.

For many practical reasons we rather use 360 of longitude, not 180/180. So to say both methods co-exist.

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Old 26-06-2012, 13:18   #25
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Re: Longitude, Why East or West.

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Gosh, only one step away from decimalising it Keep this up and we can do away with the whole NSEW thing

Seriously, good point, I hadn't seen how easy it was to convert lat to 180 degress rather than + & - 90
your gps does it all the time,then converts it back so imbeciles can read it
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Old 26-06-2012, 13:40   #26
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Re: Longitude, Why East or West.

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Gosh, only one step away from decimalising it Keep this up and we can do away with the whole NSEW thing

Seriously, good point, I hadn't seen how easy it was to convert lat to 180 degress rather than + & - 90
Most survey charts used in the offshore industry, and I guess in other fields, use Northings and Eastings as the co-ordinate system. So some bu#%er has already sneaked in and done away with South and West
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Old 26-06-2012, 14:24   #27
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Re: Longitude, Why East or West.

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Originally Posted by Wotname View Post
Well yes, the French used Paris until quite recently, forgotten when they stopped but IIRC, it was only in the last century or two. Russians (and perhaps Italians ?) had their own prime meridians and I assume other nations also.
Do you suppose the Brits won the argument since they invented effective chronometers so one's east/west position could be accurately determined?
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Old 26-06-2012, 17:12   #28
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Re: Longitude, Why East or West.

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Do you suppose the Brits won the argument since they invented effective chronometers so one's east/west position could be accurately determined?
Nah, they won the argument by having maritime supremacy and beat the c#@p of the others just at the right moment in history when science could handle longitude effectively!

If the art of navigational science (contradiction ?) peaked a few centuries earlier, the prime meridian would run through Madrid or elsewhere!
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Old 26-06-2012, 17:15   #29
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Re: Longitude, Why East or West.

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Originally Posted by nigel1 View Post
Most survey charts used in the offshore industry, and I guess in other fields, use Northings and Eastings as the co-ordinate system. So some bu#%er has already sneaked in and done away with South and West
Yea, must look into at that sometime I note my GPS can output in N & E also .
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Old 26-06-2012, 18:01   #30
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Re: Longitude, Why East or West.

My understanding of various readings, is that the lunar distance method , make popular by Maskelyne and promoted by the Royal Observatory at Greenwich, standardized the mariners time reference at Greenwich, Since time east was plus and time west was minus and longitude is merely an expression of time, it followed that Longitude was expressed in + and - degrees around greenwich.

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