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Old 26-06-2012, 18:25   #31
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Re: Longitude, Why East or West.

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Originally Posted by Wotname View Post
Yea, must look into at that sometime I note my GPS can output in N & E also .
Yes, as Nigel pointed out in the Offshore Eastings/Northings are often used, it does make for an interesting wtf moment when survey send us a bunch of coordinates in E/N's, we usually just send them back and get them to do the conversion.....which is purely an arse covering exersise...

My current pos'n is, Easting: 519873.094 - Northing: 12995293.394

Some good info here if you are interested....

Geodesy and Global Navigation Systems - Geoscience Australia
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Old 26-06-2012, 19:05   #32
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Re: Longitude, Why East or West.

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Originally Posted by goboatingnow View Post
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.

Dave
Makes eminently good sense to me.

As far as latitude goes, given that the equator represents the mean plane of the sun, and that it travels approximately symmetrically about this mean, (and consequently multiple navigational and climate phenomena are similarly symmetrical), it seems to me that a "North Pole Zero" (or 180 ;-) would be pretty inconvenient, yielding lopsided figures for locations equidistant north and south of the equator (like Cancer vs Capricorn, for one example)

(incidentally, standard engineering practice is for planes of symmetry to represent zero datums wherever possible, for convenience and fewer errors).
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Old 26-06-2012, 19:24   #33
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There is a whole book on this subject (I guess probably more than one) but this one is like $3.00 for kindle. "Longitude" by Dava Sobel It was a quick read if you really wanna know all the political nitty gritty behind it.
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Old 27-06-2012, 02:15   #34
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Re: Longitude, Why East or West.

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Originally Posted by david7 View Post
There is a whole book on this subject (I guess probably more than one) but this one is like $3.00 for kindle. "Longitude" by Dava Sobel It was a quick read if you really wanna know all the political nitty gritty behind it.
+1
It is a really good read, and was also made into a TV mini series.
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